//! Publiseringsmotor: Tera-templates med innebygde temaer.
//!
//! Fire temaer: avis, magasin, blogg, tidsskrift.
//! Hvert tema har artikkelmal + forside-mal.
//! CSS-variabler for theme_config-overstyring.
//!
//! Artikler rendres til HTML via Tera, lagres i CAS med SEO-metadata
//! (OG-tags, canonical, JSON-LD). Noden oppdateres med
//! `metadata.rendered.html_hash` + `renderer_version`.
//!
//! Ref: docs/concepts/publisering.md § "Temaer", "HTML-rendering og CAS"

use std::collections::HashMap;
use std::sync::Arc;

use axum::{
    extract::{Path, Query, State},
    http::{header, StatusCode},
    response::Response,
};
use chrono::{DateTime, Datelike, Utc};
use rand::seq::SliceRandom;
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use tera::{Context, Tera};
use tokio::sync::RwLock;
use uuid::Uuid;

use crate::cas::CasStore;
use crate::jobs;
use crate::tiptap;
use crate::AppState;

/// Renderer-versjon. Økes ved mal-/template-endringer.
/// Brukes for å identifisere artikler som trenger re-rendering (oppgave 14.14).
pub const RENDERER_VERSION: i64 = 2;

// =============================================================================
// Tema-konfigurasjon fra publishing-trait
// =============================================================================

#[derive(Deserialize, Default, Debug)]
pub struct PublishingConfig {
    pub slug: Option<String>,
    pub theme: Option<String>,
    #[serde(default)]
    pub theme_config: ThemeConfig,
    pub custom_domain: Option<String>,
    pub index_mode: Option<String>,
    pub index_cache_ttl: Option<u64>,
    pub featured_max: Option<i64>,
    pub stream_page_size: Option<i64>,
    /// Krever redaksjonell godkjenning for publisering.
    /// Når true: members bruker submitted_to-flyten, kun owner/admin kan opprette belongs_to.
    #[serde(default)]
    pub require_approval: bool,
    /// Roller som kan opprette submitted_to-edges til samlingen.
    /// Verdier: "owner", "admin", "member", "reader". Default: ["member"].
    #[serde(default = "default_submission_roles")]
    pub submission_roles: Vec<String>,
}

fn default_submission_roles() -> Vec<String> {
    vec!["member".to_string()]
}

#[derive(Deserialize, Default, Debug, Clone, Serialize)]
pub struct ThemeConfig {
    #[serde(default)]
    pub colors: ColorConfig,
    #[serde(default)]
    pub typography: TypographyConfig,
    #[serde(default)]
    pub layout: LayoutConfig,
    pub logo_hash: Option<String>,
}

#[derive(Deserialize, Default, Debug, Clone, Serialize)]
pub struct ColorConfig {
    pub primary: Option<String>,
    pub accent: Option<String>,
    pub background: Option<String>,
    pub text: Option<String>,
    pub muted: Option<String>,
}

#[derive(Deserialize, Default, Debug, Clone, Serialize)]
pub struct TypographyConfig {
    pub heading_font: Option<String>,
    pub body_font: Option<String>,
}

#[derive(Deserialize, Default, Debug, Clone, Serialize)]
pub struct LayoutConfig {
    pub max_width: Option<String>,
}

// =============================================================================
// SEO-data
// =============================================================================

/// SEO-metadata for artikkelrendering.
#[derive(Serialize, Clone)]
pub struct SeoData {
    pub og_title: String,
    pub description: String,
    pub canonical_url: String,
    pub og_image: Option<String>,
    pub json_ld: String,
}

fn build_seo_data(
    article: &ArticleData,
    collection_title: &str,
    canonical_url: &str,
) -> SeoData {
    let description = article
        .summary
        .as_deref()
        .unwrap_or("")
        .to_string();

    let json_ld = build_json_ld(article, collection_title, canonical_url);

    // Bygg OG-image URL fra CAS-hash hvis tilgjengelig
    let og_image = article.og_image.as_ref().map(|hash| format!("/cas/{hash}"));

    SeoData {
        og_title: article.title.clone(),
        description,
        canonical_url: canonical_url.to_string(),
        og_image,
        json_ld,
    }
}

fn build_json_ld(
    article: &ArticleData,
    publisher_name: &str,
    canonical_url: &str,
) -> String {
    let ld = serde_json::json!({
        "@context": "https://schema.org",
        "@type": "Article",
        "headline": article.title,
        "datePublished": article.published_at,
        "url": canonical_url,
        "publisher": {
            "@type": "Organization",
            "name": publisher_name
        },
        "description": article.summary.as_deref().unwrap_or("")
    });
    // Escape </script> sekvenser for sikker embedding i <script>-tag.
    // Uten dette kan brukerinnhold bryte ut av JSON-LD-blokken (XSS).
    ld.to_string().replace("</", "<\\/")
}

// =============================================================================
// Innebygde temaer — Tera-templates
// =============================================================================

/// Tema-defaults for CSS-variabler per tema.
struct ThemeDefaults {
    primary: &'static str,
    accent: &'static str,
    background: &'static str,
    text: &'static str,
    muted: &'static str,
    heading_font: &'static str,
    body_font: &'static str,
    max_width: &'static str,
}

fn theme_defaults(theme: &str) -> ThemeDefaults {
    match theme {
        "avis" => ThemeDefaults {
            primary: "#1a1a2e",
            accent: "#e94560",
            background: "#ffffff",
            text: "#1a1a2e",
            muted: "#6b7280",
            heading_font: "'Georgia', 'Times New Roman', serif",
            body_font: "'Charter', 'Georgia', serif",
            max_width: "1200px",
        },
        "magasin" => ThemeDefaults {
            primary: "#2d3436",
            accent: "#0984e3",
            background: "#fafafa",
            text: "#2d3436",
            muted: "#636e72",
            heading_font: "'Playfair Display', 'Georgia', serif",
            body_font: "system-ui, -apple-system, sans-serif",
            max_width: "1100px",
        },
        "blogg" => ThemeDefaults {
            primary: "#2c3e50",
            accent: "#3498db",
            background: "#ffffff",
            text: "#333333",
            muted: "#7f8c8d",
            heading_font: "system-ui, -apple-system, sans-serif",
            body_font: "system-ui, -apple-system, sans-serif",
            max_width: "720px",
        },
        "tidsskrift" => ThemeDefaults {
            primary: "#1a1a1a",
            accent: "#8b0000",
            background: "#fffff8",
            text: "#1a1a1a",
            muted: "#555555",
            heading_font: "'Georgia', 'Times New Roman', serif",
            body_font: "'Georgia', 'Times New Roman', serif",
            max_width: "680px",
        },
        // Fallback til blogg-defaults
        _ => theme_defaults("blogg"),
    }
}

/// Generer CSS-variabler fra theme_config med tema-defaults som fallback.
fn build_css_variables(theme: &str, config: &ThemeConfig) -> String {
    let defaults = theme_defaults(theme);
    format!(
        r#":root {{
  --color-primary: {primary};
  --color-accent: {accent};
  --color-background: {background};
  --color-text: {text};
  --color-muted: {muted};
  --font-heading: {heading_font};
  --font-body: {body_font};
  --layout-max-width: {max_width};
}}"#,
        primary = config.colors.primary.as_deref().unwrap_or(defaults.primary),
        accent = config.colors.accent.as_deref().unwrap_or(defaults.accent),
        background = config.colors.background.as_deref().unwrap_or(defaults.background),
        text = config.colors.text.as_deref().unwrap_or(defaults.text),
        muted = config.colors.muted.as_deref().unwrap_or(defaults.muted),
        heading_font = config.typography.heading_font.as_deref().unwrap_or(defaults.heading_font),
        body_font = config.typography.body_font.as_deref().unwrap_or(defaults.body_font),
        max_width = config.layout.max_width.as_deref().unwrap_or(defaults.max_width),
    )
}

// =============================================================================
// Tera engine med innebygde templates
// =============================================================================

/// Bygg Tera-instans med alle innebygde temaer.
pub fn build_tera() -> Tera {
    let mut tera = Tera::default();

    // Base-template (felles for alle temaer)
    tera.add_raw_template("base.html", include_str!("templates/base.html"))
        .expect("Feil i base.html template");

    // Avis
    tera.add_raw_template("avis/article.html", include_str!("templates/avis/article.html"))
        .expect("Feil i avis/article.html");
    tera.add_raw_template("avis/index.html", include_str!("templates/avis/index.html"))
        .expect("Feil i avis/index.html");

    // Magasin
    tera.add_raw_template("magasin/article.html", include_str!("templates/magasin/article.html"))
        .expect("Feil i magasin/article.html");
    tera.add_raw_template("magasin/index.html", include_str!("templates/magasin/index.html"))
        .expect("Feil i magasin/index.html");

    // Blogg
    tera.add_raw_template("blogg/article.html", include_str!("templates/blogg/article.html"))
        .expect("Feil i blogg/article.html");
    tera.add_raw_template("blogg/index.html", include_str!("templates/blogg/index.html"))
        .expect("Feil i blogg/index.html");

    // Tidsskrift
    tera.add_raw_template("tidsskrift/article.html", include_str!("templates/tidsskrift/article.html"))
        .expect("Feil i tidsskrift/article.html");
    tera.add_raw_template("tidsskrift/index.html", include_str!("templates/tidsskrift/index.html"))
        .expect("Feil i tidsskrift/index.html");

    // Dynamiske sider (delte templates, temaet styres via CSS-variabler i base.html)
    tera.add_raw_template("category.html", include_str!("templates/category.html"))
        .expect("Feil i category.html");
    tera.add_raw_template("archive.html", include_str!("templates/archive.html"))
        .expect("Feil i archive.html");
    tera.add_raw_template("search.html", include_str!("templates/search.html"))
        .expect("Feil i search.html");
    tera.add_raw_template("about.html", include_str!("templates/about.html"))
        .expect("Feil i about.html");

    tera
}

// =============================================================================
// Datamodeller for rendering
// =============================================================================

#[derive(Serialize, Clone)]
pub struct ArticleData {
    pub id: String,
    pub short_id: String,
    pub title: String,
    pub subtitle: Option<String>,
    pub content: String,
    pub summary: Option<String>,
    pub og_image: Option<String>,
    pub published_at: String,
    pub published_at_short: String,
}

#[derive(Serialize)]
pub struct IndexData {
    pub title: String,
    pub description: Option<String>,
    pub hero: Option<ArticleData>,
    pub featured: Vec<ArticleData>,
    pub stream: Vec<ArticleData>,
}

// =============================================================================
// In-memory index-cache (dynamisk modus)
// =============================================================================

/// Cachet forside-HTML med utløpstid.
pub struct CachedIndex {
    html: String,
    expires_at: DateTime<Utc>,
    /// Aktive A/B-variant edge-IDs som vises i denne cachede forsiden.
    /// Brukes for impression-logging ved serve.
    /// Tuple: (edge_id, article_id)
    active_ab_variants: Vec<(Uuid, Uuid)>,
}

/// Thread-safe cache for forside-rendering (dynamisk modus).
/// Nøkkel: collection UUID. Verdi: rendret HTML med TTL.
pub type IndexCache = Arc<RwLock<HashMap<Uuid, CachedIndex>>>;

/// Opprett en ny tom IndexCache.
pub fn new_index_cache() -> IndexCache {
    Arc::new(RwLock::new(HashMap::new()))
}

/// Invalider cache for en gitt samling.
pub async fn invalidate_index_cache(cache: &IndexCache, collection_id: Uuid) {
    let mut map = cache.write().await;
    if map.remove(&collection_id).is_some() {
        tracing::info!(collection_id = %collection_id, "Forside-cache invalidert");
    }
}

// =============================================================================
// Render-funksjoner
// =============================================================================

/// Render en artikkel med gitt tema og SEO-metadata.
pub fn render_article(
    tera: &Tera,
    theme: &str,
    config: &ThemeConfig,
    article: &ArticleData,
    collection_title: &str,
    base_url: &str,
    seo: &SeoData,
    has_rss: bool,
) -> Result<String, tera::Error> {
    let css_vars = build_css_variables(theme, config);
    let template_name = format!("{theme}/article.html");

    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("article", article);
    ctx.insert("collection_title", collection_title);
    ctx.insert("base_url", base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("seo", seo);
    ctx.insert("has_rss", &has_rss);

    tera.render(&template_name, &ctx)
}

/// Render forsiden med gitt tema.
pub fn render_index(
    tera: &Tera,
    theme: &str,
    config: &ThemeConfig,
    index: &IndexData,
    base_url: &str,
    has_rss: bool,
) -> Result<String, tera::Error> {
    let css_vars = build_css_variables(theme, config);
    let template_name = format!("{theme}/index.html");

    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("index", index);
    ctx.insert("base_url", base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &has_rss);

    tera.render(&template_name, &ctx)
}

// =============================================================================
// CAS-rendering: render artikkel → lagre i CAS → oppdater node metadata
// =============================================================================

/// Render en artikkel til HTML, lagre i CAS, og oppdater nodens metadata.
///
/// Kalles fra jobbkø (`render_article`-jobb) når en `belongs_to`-edge
/// opprettes til en samling med `publishing`-trait.
///
/// Steg:
/// 1. Hent samlingens publishing-konfig (tema, slug, custom_domain)
/// 2. Hent artikkelens metadata.document (TipTap JSON)
/// 3. Konverter document → HTML via tiptap::document_to_html()
/// 4. Render full artikkelside med Tera-template + SEO
/// 5. Lagre HTML i CAS
/// 6. Oppdater nodens metadata.rendered (html_hash, rendered_at, renderer_version)
pub async fn render_article_to_cas(
    db: &PgPool,
    cas: &CasStore,
    node_id: Uuid,
    collection_id: Uuid,
) -> Result<serde_json::Value, String> {
    // 1. Hent samlingens publishing-konfig
    let collection_row: Option<(Option<String>, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT title, metadata
        FROM nodes
        WHERE id = $1 AND node_kind = 'collection'
        "#,
    )
    .bind(collection_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av samling: {e}"))?;

    let Some((collection_title_opt, collection_metadata)) = collection_row else {
        return Err(format!("Samling {collection_id} finnes ikke"));
    };

    let coll_traits = collection_metadata.get("traits");

    let publishing_config: PublishingConfig = coll_traits
        .and_then(|t| t.get("publishing"))
        .cloned()
        .map(|v| serde_json::from_value(v).unwrap_or_default())
        .unwrap_or_default();

    let has_rss = coll_traits.and_then(|t| t.get("rss")).is_some();

    let slug = publishing_config.slug.as_deref().unwrap_or("unknown");
    let theme = publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &publishing_config.theme_config;
    let collection_title = collection_title_opt.unwrap_or_else(|| slug.to_string());

    // 2. Hent artikkelens data + metadata.document + edge-metadata
    let article_row: Option<(Uuid, Option<String>, Option<String>, serde_json::Value, DateTime<Utc>)> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.metadata, n.created_at
        FROM nodes n
        WHERE n.id = $1
        "#,
    )
    .bind(node_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av artikkel: {e}"))?;

    let Some((id, title, content, metadata, created_at)) = article_row else {
        return Err(format!("Artikkel {node_id} finnes ikke"));
    };

    // Hent publish_at fra edge-metadata
    let edge_meta: Option<(Option<serde_json::Value>,)> = sqlx::query_as(
        r#"
        SELECT metadata
        FROM edges
        WHERE source_id = $1 AND target_id = $2 AND edge_type = 'belongs_to'
        LIMIT 1
        "#,
    )
    .bind(node_id)
    .bind(collection_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av edge: {e}"))?;

    let publish_at = edge_meta
        .as_ref()
        .and_then(|(m,)| m.as_ref())
        .and_then(|m| m.get("publish_at"))
        .and_then(|v| v.as_str())
        .and_then(|s| s.parse::<DateTime<Utc>>().ok())
        .unwrap_or(created_at);

    // 3. Konverter metadata.document til HTML (eller bruk content som fallback)
    let article_html = if let Some(doc) = metadata.get("document") {
        let html = tiptap::document_to_html(doc);
        if html.is_empty() {
            // Fallback til content-feltet
            content.unwrap_or_default()
        } else {
            html
        }
    } else {
        // Ingen document — bruk content direkte
        content.unwrap_or_default()
    };

    let short_id = id.to_string()[..8].to_string();

    // 3b. Hent presentasjonselementer (title/subtitle/summary/og_image/og_description)
    let pres = fetch_presentation_elements(db, node_id).await
        .map_err(|e| format!("Feil ved henting av presentasjonselementer: {e}"))?;

    // Bruk presentasjonselement-tittel hvis tilgjengelig, ellers artikkelens interne tittel
    let article_title = pres.best_title()
        .unwrap_or_else(|| title.unwrap_or_else(|| "Uten tittel".to_string()));

    // Bruk presentasjonselement-ingress hvis tilgjengelig, ellers auto-generert
    let summary_text = pres.best_summary()
        .unwrap_or_else(|| truncate(&article_html.replace("<p>", "").replace("</p>", " ").replace('\n', " "), 200));

    let article_data = ArticleData {
        id: id.to_string(),
        short_id: short_id.clone(),
        title: article_title,
        subtitle: pres.best_subtitle(),
        content: article_html,
        summary: Some(summary_text),
        og_image: pres.best_og_image(),
        published_at: publish_at.to_rfc3339(),
        published_at_short: publish_at.format("%e. %B %Y").to_string(),
    };

    // 4. Bygg SEO-data og render med Tera
    let base_url = publishing_config
        .custom_domain
        .as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let canonical_url = format!("{base_url}/{short_id}");
    let seo = build_seo_data(&article_data, &collection_title, &canonical_url);

    let tera = build_tera();
    let html = render_article(&tera, theme, config, &article_data, &collection_title, &base_url, &seo, has_rss)
        .map_err(|e| format!("Tera render-feil: {e}"))?;

    // 5. Lagre i CAS
    let store_result = cas
        .store(html.as_bytes())
        .await
        .map_err(|e| format!("CAS-lagring feilet: {e}"))?;

    tracing::info!(
        node_id = %node_id,
        hash = %store_result.hash,
        size = store_result.size,
        deduplicated = store_result.already_existed,
        "Artikkel rendret og lagret i CAS"
    );

    // 6. Oppdater nodens metadata.rendered
    let now = Utc::now();
    sqlx::query(
        r#"
        UPDATE nodes
        SET metadata = jsonb_set(
            jsonb_set(
                jsonb_set(
                    CASE WHEN metadata ? 'rendered'
                        THEN metadata
                        ELSE jsonb_set(metadata, '{rendered}', '{}'::jsonb)
                    END,
                    '{rendered,html_hash}',
                    to_jsonb($2::text)
                ),
                '{rendered,rendered_at}',
                to_jsonb($3::text)
            ),
            '{rendered,renderer_version}',
            to_jsonb($4::bigint)
        )
        WHERE id = $1
        "#,
    )
    .bind(node_id)
    .bind(&store_result.hash)
    .bind(now.to_rfc3339())
    .bind(RENDERER_VERSION)
    .execute(db)
    .await
    .map_err(|e| format!("Feil ved oppdatering av metadata.rendered: {e}"))?;

    tracing::info!(
        node_id = %node_id,
        html_hash = %store_result.hash,
        renderer_version = RENDERER_VERSION,
        "metadata.rendered oppdatert"
    );

    Ok(serde_json::json!({
        "html_hash": store_result.hash,
        "size": store_result.size,
        "renderer_version": RENDERER_VERSION
    }))
}

/// Render forsiden til CAS (statisk modus).
///
/// Henter hero/featured/stream med tre indekserte spørringer,
/// rendrer via Tera-template, lagrer HTML i CAS, og oppdaterer
/// samlingens metadata.rendered_index med index_hash.
pub async fn render_index_to_cas(
    db: &PgPool,
    cas: &CasStore,
    collection_id: Uuid,
) -> Result<serde_json::Value, String> {
    // Hent samlingens konfig
    let collection_row: Option<(Option<String>, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT title, metadata
        FROM nodes
        WHERE id = $1 AND node_kind = 'collection'
        "#,
    )
    .bind(collection_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av samling: {e}"))?;

    let Some((collection_title_opt, collection_metadata)) = collection_row else {
        return Err(format!("Samling {collection_id} finnes ikke"));
    };

    let idx_traits = collection_metadata.get("traits");

    let publishing_config: PublishingConfig = idx_traits
        .and_then(|t| t.get("publishing"))
        .cloned()
        .map(|v| serde_json::from_value(v).unwrap_or_default())
        .unwrap_or_default();

    let has_rss = idx_traits.and_then(|t| t.get("rss")).is_some();

    let slug = publishing_config.slug.as_deref().unwrap_or("unknown");
    let theme = publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &publishing_config.theme_config;
    let collection_title = collection_title_opt.unwrap_or_else(|| slug.to_string());
    let featured_max = publishing_config.featured_max.unwrap_or(4);
    let stream_page_size = publishing_config.stream_page_size.unwrap_or(20);

    let base_url = publishing_config
        .custom_domain
        .as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    // Hent artikler med tre indekserte spørringer (A/B-rotasjon inkludert)
    let (hero, featured, stream, _ab_variants) =
        fetch_index_articles_optimized(db, collection_id, featured_max, stream_page_size).await
            .map_err(|e| format!("Feil ved henting av forsideartikler: {e}"))?;

    let index_data = IndexData {
        title: collection_title,
        description: None,
        hero,
        featured,
        stream,
    };

    // Render med Tera
    let tera = build_tera();
    let html = render_index(&tera, theme, config, &index_data, &base_url, has_rss)
        .map_err(|e| format!("Tera render-feil (index): {e}"))?;

    // Lagre i CAS
    let store_result = cas
        .store(html.as_bytes())
        .await
        .map_err(|e| format!("CAS-lagring feilet: {e}"))?;

    tracing::info!(
        collection_id = %collection_id,
        hash = %store_result.hash,
        size = store_result.size,
        deduplicated = store_result.already_existed,
        "Forside rendret og lagret i CAS"
    );

    // Oppdater samlingens metadata.rendered_index
    let now = Utc::now();
    sqlx::query(
        r#"
        UPDATE nodes
        SET metadata = jsonb_set(
            jsonb_set(
                jsonb_set(
                    CASE WHEN metadata ? 'rendered_index'
                        THEN metadata
                        ELSE jsonb_set(metadata, '{rendered_index}', '{}'::jsonb)
                    END,
                    '{rendered_index,index_hash}',
                    to_jsonb($2::text)
                ),
                '{rendered_index,rendered_at}',
                to_jsonb($3::text)
            ),
            '{rendered_index,renderer_version}',
            to_jsonb($4::bigint)
        )
        WHERE id = $1
        "#,
    )
    .bind(collection_id)
    .bind(&store_result.hash)
    .bind(now.to_rfc3339())
    .bind(RENDERER_VERSION)
    .execute(db)
    .await
    .map_err(|e| format!("Feil ved oppdatering av metadata.rendered_index: {e}"))?;

    tracing::info!(
        collection_id = %collection_id,
        index_hash = %store_result.hash,
        "metadata.rendered_index oppdatert"
    );

    Ok(serde_json::json!({
        "index_hash": store_result.hash,
        "size": store_result.size,
        "renderer_version": RENDERER_VERSION
    }))
}

// =============================================================================
// Database-spørringer
// =============================================================================

struct CollectionRow {
    id: Uuid,
    title: Option<String>,
    publishing_config: PublishingConfig,
    has_rss: bool,
}

/// Finn samling med publishing-trait basert på slug.
async fn find_publishing_collection(
    db: &PgPool,
    slug: &str,
) -> Result<Option<CollectionRow>, sqlx::Error> {
    let row: Option<(Uuid, Option<String>, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT id, title, metadata
        FROM nodes
        WHERE node_kind = 'collection'
          AND metadata->'traits'->'publishing'->>'slug' = $1
        LIMIT 1
        "#,
    )
    .bind(slug)
    .fetch_optional(db)
    .await?;

    let Some((id, title, metadata)) = row else {
        return Ok(None);
    };

    let traits = metadata.get("traits");

    let publishing_config: PublishingConfig = traits
        .and_then(|t| t.get("publishing"))
        .cloned()
        .map(|v| serde_json::from_value(v).unwrap_or_default())
        .unwrap_or_default();

    let has_rss = traits
        .and_then(|t| t.get("rss"))
        .is_some();

    Ok(Some(CollectionRow {
        id,
        title,
        publishing_config,
        has_rss,
    }))
}

/// Finn publishing-samling basert på samlings-ID.
/// Returnerer None hvis samlingen ikke har publishing-trait.
pub async fn find_publishing_collection_by_id(
    db: &PgPool,
    collection_id: Uuid,
) -> Result<Option<PublishingConfig>, sqlx::Error> {
    let row: Option<(serde_json::Value,)> = sqlx::query_as(
        r#"
        SELECT metadata
        FROM nodes
        WHERE id = $1
          AND node_kind = 'collection'
          AND metadata->'traits' ? 'publishing'
        "#,
    )
    .bind(collection_id)
    .fetch_optional(db)
    .await?;

    let Some((metadata,)) = row else {
        return Ok(None);
    };

    let config: PublishingConfig = metadata
        .get("traits")
        .and_then(|t| t.get("publishing"))
        .cloned()
        .map(|v| serde_json::from_value(v).unwrap_or_default())
        .unwrap_or_default();

    Ok(Some(config))
}

/// Hent artikkeldata for en enkelt node (belongs_to samlingen).
/// Returnerer også nodens metadata (for å sjekke rendered.html_hash).
async fn fetch_article(
    db: &PgPool,
    collection_id: Uuid,
    article_short_id: &str,
) -> Result<Option<FetchedArticle>, sqlx::Error> {
    // short_id er de første 8 tegnene av UUID
    let pattern = format!("{article_short_id}%");

    let row: Option<(Uuid, Option<String>, Option<String>, serde_json::Value, DateTime<Utc>, Option<serde_json::Value>)> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.metadata, n.created_at, e.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND n.id::text LIKE $2
        LIMIT 1
        "#,
    )
    .bind(collection_id)
    .bind(&pattern)
    .fetch_optional(db)
    .await?;

    let Some((id, title, content, node_metadata, created_at, edge_meta)) = row else {
        return Ok(None);
    };

    let publish_at = edge_meta
        .as_ref()
        .and_then(|m| m.get("publish_at"))
        .and_then(|v| v.as_str())
        .and_then(|s| s.parse::<DateTime<Utc>>().ok())
        .unwrap_or(created_at);

    // Artikler med fremtidig publish_at er ikke tilgjengelige ennå
    if publish_at > Utc::now() {
        return Ok(None);
    }

    // Sjekk om det finnes rendret HTML i CAS
    let html_hash = node_metadata
        .get("rendered")
        .and_then(|r| r.get("html_hash"))
        .and_then(|h| h.as_str())
        .map(|s| s.to_string());

    // Konverter metadata.document til HTML, eller bruk content som fallback
    let article_html = if let Some(doc) = node_metadata.get("document") {
        let html = tiptap::document_to_html(doc);
        if html.is_empty() {
            content.unwrap_or_default()
        } else {
            html
        }
    } else {
        content.unwrap_or_default()
    };

    // Hent presentasjonselementer
    let pres = fetch_presentation_elements(db, id).await?;

    let article_title = pres.best_title()
        .unwrap_or_else(|| title.unwrap_or_else(|| "Uten tittel".to_string()));

    let summary_text = pres.best_summary()
        .unwrap_or_else(|| truncate(
            &article_html.replace("<p>", "").replace("</p>", " ").replace('\n', " "),
            200,
        ));

    let article = ArticleData {
        id: id.to_string(),
        short_id: id.to_string()[..8].to_string(),
        title: article_title,
        subtitle: pres.best_subtitle(),
        content: article_html,
        summary: Some(summary_text),
        og_image: pres.best_og_image(),
        published_at: publish_at.to_rfc3339(),
        published_at_short: publish_at.format("%e. %B %Y").to_string(),
    };

    Ok(Some(FetchedArticle {
        article,
        html_hash,
        edge_meta,
    }))
}

struct FetchedArticle {
    article: ArticleData,
    html_hash: Option<String>,
    #[allow(dead_code)]
    edge_meta: Option<serde_json::Value>,
}

/// Hent forsideartikler med tre separate, indekserte spørringer.
///
/// Hver spørring filtrerer på slot i edge.metadata og bruker
/// GIN-indeks på edges.metadata. Mer effektivt enn å hente alt
/// og filtrere i Rust, spesielt med mange artikler.
async fn fetch_index_articles_optimized(
    db: &PgPool,
    collection_id: Uuid,
    featured_max: i64,
    stream_page_size: i64,
) -> Result<(Option<ArticleData>, Vec<ArticleData>, Vec<ArticleData>, Vec<(Uuid, Uuid)>), sqlx::Error> {
    // Hjelpefunksjon for å konvertere rader til ArticleData
    fn row_to_article(
        id: Uuid,
        title: Option<String>,
        content: Option<String>,
        created_at: DateTime<Utc>,
        edge_meta: Option<serde_json::Value>,
    ) -> ArticleData {
        let publish_at = edge_meta
            .as_ref()
            .and_then(|m| m.get("publish_at"))
            .and_then(|v| v.as_str())
            .and_then(|s| s.parse::<DateTime<Utc>>().ok())
            .unwrap_or(created_at);

        let summary = content.as_deref().map(|c| truncate(c, 200));

        ArticleData {
            id: id.to_string(),
            short_id: id.to_string()[..8].to_string(),
            title: title.unwrap_or_else(|| "Uten tittel".to_string()),
            subtitle: None,
            content: content.unwrap_or_default(),
            summary,
            og_image: None,
            published_at: publish_at.to_rfc3339(),
            published_at_short: publish_at.format("%e. %B %Y").to_string(),
        }
    }

    type Row = (Uuid, Option<String>, Option<String>, DateTime<Utc>, Option<serde_json::Value>);

    // 1. Hero: slot = "hero", maks 1
    // Ekskluderer artikler med fremtidig publish_at (planlagt publisering)
    let hero_row: Option<Row> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.created_at, e.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND e.metadata->>'slot' = 'hero'
          AND (e.metadata->>'publish_at' IS NULL
               OR (e.metadata->>'publish_at')::timestamptz <= now())
        LIMIT 1
        "#,
    )
    .bind(collection_id)
    .fetch_optional(db)
    .await?;

    let hero = hero_row.map(|(id, title, content, created_at, edge_meta)| {
        row_to_article(id, title, content, created_at, edge_meta)
    });

    // 2. Featured: slot = "featured", sortert på slot_order
    let featured_rows: Vec<Row> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.created_at, e.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND e.metadata->>'slot' = 'featured'
          AND (e.metadata->>'publish_at' IS NULL
               OR (e.metadata->>'publish_at')::timestamptz <= now())
        ORDER BY (e.metadata->>'slot_order')::int ASC NULLS LAST
        LIMIT $2
        "#,
    )
    .bind(collection_id)
    .bind(featured_max)
    .fetch_all(db)
    .await?;

    let featured: Vec<ArticleData> = featured_rows
        .into_iter()
        .map(|(id, title, content, created_at, edge_meta)| {
            row_to_article(id, title, content, created_at, edge_meta)
        })
        .collect();

    // 3. Strøm: slot IS NULL (eller mangler), sortert på publish_at
    let stream_rows: Vec<Row> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.created_at, e.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND (e.metadata->>'slot' IS NULL OR e.metadata->>'slot' = '')
          AND (e.metadata->>'publish_at' IS NULL
               OR (e.metadata->>'publish_at')::timestamptz <= now())
        ORDER BY COALESCE(
            (e.metadata->>'publish_at')::timestamptz,
            n.created_at
        ) DESC
        LIMIT $2
        "#,
    )
    .bind(collection_id)
    .bind(stream_page_size)
    .fetch_all(db)
    .await?;

    let stream: Vec<ArticleData> = stream_rows
        .into_iter()
        .map(|(id, title, content, created_at, edge_meta)| {
            row_to_article(id, title, content, created_at, edge_meta)
        })
        .collect();

    // Berik med presentasjonselementer (batch: hent alle i én spørring)
    let mut all_ids: Vec<Uuid> = vec![];
    if let Some(ref h) = hero {
        if let Ok(uid) = h.id.parse::<Uuid>() { all_ids.push(uid); }
    }
    for a in &featured { if let Ok(uid) = a.id.parse::<Uuid>() { all_ids.push(uid); } }
    for a in &stream { if let Ok(uid) = a.id.parse::<Uuid>() { all_ids.push(uid); } }

    let pres_map = fetch_presentation_elements_batch(db, &all_ids).await
        .unwrap_or_default();

    // Samle aktive A/B-variant edge-IDs for impression-logging
    let mut active_ab_variants: Vec<(Uuid, Uuid)> = vec![];

    /// Berik artikkel med presentasjonselementer via A/B-rotasjon.
    /// Returnerer edge-IDs for varianter som er del av aktive A/B-tester.
    fn enrich_with_ab(article: &mut ArticleData, pres: &PresentationElements) -> Vec<(Uuid, Uuid)> {
        let mut variants = vec![];
        let article_id = article.id.parse::<Uuid>().unwrap_or_default();

        // Tittel: AB-rotasjon
        if let Some((text, ab_edge)) = pres.ab_title() {
            article.title = text;
            if let Some(eid) = ab_edge { variants.push((eid, article_id)); }
        }
        // Subtitle: bruk best (sjelden A/B-testet)
        if let Some(s) = pres.best_subtitle() { article.subtitle = Some(s); }
        // Summary: AB-rotasjon
        if let Some((text, ab_edge)) = pres.ab_summary() {
            article.summary = Some(text);
            if let Some(eid) = ab_edge { variants.push((eid, article_id)); }
        }
        // OG-image: AB-rotasjon
        if let Some((hash, ab_edge)) = pres.ab_og_image() {
            article.og_image = Some(hash);
            if let Some(eid) = ab_edge { variants.push((eid, article_id)); }
        }
        variants
    }

    let mut hero = hero;
    if let Some(ref mut h) = hero {
        if let Ok(uid) = h.id.parse::<Uuid>() {
            if let Some(pres) = pres_map.get(&uid) {
                active_ab_variants.extend(enrich_with_ab(h, pres));
            }
        }
    }
    let mut featured = featured;
    for a in &mut featured {
        if let Ok(uid) = a.id.parse::<Uuid>() {
            if let Some(pres) = pres_map.get(&uid) {
                active_ab_variants.extend(enrich_with_ab(a, pres));
            }
        }
    }
    let mut stream = stream;
    for a in &mut stream {
        if let Ok(uid) = a.id.parse::<Uuid>() {
            if let Some(pres) = pres_map.get(&uid) {
                active_ab_variants.extend(enrich_with_ab(a, pres));
            }
        }
    }

    Ok((hero, featured, stream, active_ab_variants))
}

// =============================================================================
// Presentasjonselementer: hent title/subtitle/summary/og_image fra edge-koblede noder
// =============================================================================

/// Presentasjonselementer for en artikkel.
/// Inneholder lister per type — flere varianter støttes for A/B-testing.
struct PresentationElements {
    titles: Vec<PresEl>,
    subtitles: Vec<PresEl>,
    summaries: Vec<PresEl>,
    og_images: Vec<PresEl>,
    og_descriptions: Vec<PresEl>,
}

struct PresEl {
    edge_id: Uuid,
    title: Option<String>,
    content: Option<String>,
    #[allow(dead_code)]
    node_kind: String,
    metadata: serde_json::Value,
    edge_metadata: serde_json::Value,
}

impl PresEl {
    fn ab_status(&self) -> &str {
        self.edge_metadata
            .get("ab_status")
            .and_then(|v| v.as_str())
            .unwrap_or("")
    }
}

impl PresentationElements {
    /// Velg beste variant: "winner" > "testing" > første tilgjengelige.
    /// Brukes for enkeltartikkel-rendering der vi alltid viser "best".
    fn best_of(elements: &[PresEl]) -> Option<&PresEl> {
        // Prioriter "winner"
        if let Some(el) = elements.iter().find(|e| e.ab_status() == "winner") {
            return Some(el);
        }
        // Så "testing" eller de uten ab_status (enkeltvariant)
        elements.iter().find(|e| e.ab_status() != "retired")
    }

    /// Velg variant for forside-visning med A/B-rotasjon.
    /// Returnerer (valgt element, edge_id) — edge_id brukes for impression-logging.
    /// Hvis det finnes en "winner", returneres alltid den.
    /// Hvis det finnes flere "testing"-varianter, velges tilfeldig.
    fn ab_select(elements: &[PresEl]) -> Option<&PresEl> {
        // Prioriter "winner"
        if let Some(el) = elements.iter().find(|e| e.ab_status() == "winner") {
            return Some(el);
        }
        // Filtrer til testing-kandidater (alt som ikke er retired)
        let candidates: Vec<&PresEl> = elements.iter()
            .filter(|e| e.ab_status() != "retired")
            .collect();
        if candidates.is_empty() {
            return None;
        }
        if candidates.len() == 1 {
            return Some(candidates[0]);
        }
        // Tilfeldig rotasjon mellom testing-varianter
        let mut rng = rand::thread_rng();
        candidates.choose(&mut rng).copied()
    }

    /// Sjekk om det finnes aktive A/B-tester (>1 ikke-retired variant).
    fn has_active_ab_test(elements: &[PresEl]) -> bool {
        elements.iter().filter(|e| e.ab_status() != "retired").count() > 1
    }

    fn best_title(&self) -> Option<String> {
        Self::best_of(&self.titles)
            .and_then(|el| el.title.clone().or(el.content.clone()))
    }

    fn best_subtitle(&self) -> Option<String> {
        Self::best_of(&self.subtitles)
            .and_then(|el| el.title.clone().or(el.content.clone()))
    }

    fn best_summary(&self) -> Option<String> {
        Self::best_of(&self.summaries)
            .and_then(|el| el.content.clone().or(el.title.clone()))
    }

    fn best_og_image(&self) -> Option<String> {
        Self::best_of(&self.og_images)
            .and_then(|el| el.metadata.get("cas_hash").and_then(|h| h.as_str()).map(|s| s.to_string()))
    }

    #[allow(dead_code)]
    fn best_og_description(&self) -> Option<String> {
        Self::best_of(&self.og_descriptions)
            .and_then(|el| el.content.clone().or(el.title.clone()))
    }

    /// AB-seleksjon for forside: velg tittel med rotasjon.
    fn ab_title(&self) -> Option<(String, Option<Uuid>)> {
        Self::ab_select(&self.titles)
            .and_then(|el| {
                let text = el.title.clone().or(el.content.clone())?;
                let eid = if Self::has_active_ab_test(&self.titles) { Some(el.edge_id) } else { None };
                Some((text, eid))
            })
    }

    /// AB-seleksjon for forside: velg summary med rotasjon.
    fn ab_summary(&self) -> Option<(String, Option<Uuid>)> {
        Self::ab_select(&self.summaries)
            .and_then(|el| {
                let text = el.content.clone().or(el.title.clone())?;
                let eid = if Self::has_active_ab_test(&self.summaries) { Some(el.edge_id) } else { None };
                Some((text, eid))
            })
    }

    /// AB-seleksjon for forside: velg OG-image med rotasjon.
    fn ab_og_image(&self) -> Option<(String, Option<Uuid>)> {
        Self::ab_select(&self.og_images)
            .and_then(|el| {
                let hash = el.metadata.get("cas_hash").and_then(|h| h.as_str()).map(|s| s.to_string())?;
                let eid = if Self::has_active_ab_test(&self.og_images) { Some(el.edge_id) } else { None };
                Some((hash, eid))
            })
    }
}

/// Hent alle presentasjonselementer for en artikkel.
/// Noder koblet via title/subtitle/summary/og_image/og_description-edges
/// der source_id = elementnode, target_id = artikkel.
async fn fetch_presentation_elements(
    db: &PgPool,
    article_id: Uuid,
) -> Result<PresentationElements, sqlx::Error> {
    let rows: Vec<(Uuid, String, Option<String>, Option<String>, String, serde_json::Value, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT e.id AS edge_id, e.edge_type, n.title, n.content, n.node_kind, n.metadata, e.metadata AS edge_metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type IN ('title', 'subtitle', 'summary', 'og_image', 'og_description')
        ORDER BY e.created_at
        "#,
    )
    .bind(article_id)
    .fetch_all(db)
    .await?;

    let mut titles = vec![];
    let mut subtitles = vec![];
    let mut summaries = vec![];
    let mut og_images = vec![];
    let mut og_descriptions = vec![];

    for (edge_id, edge_type, title, content, node_kind, metadata, edge_metadata) in rows {
        let el = PresEl { edge_id, title, content, node_kind, metadata, edge_metadata };
        match edge_type.as_str() {
            "title" => titles.push(el),
            "subtitle" => subtitles.push(el),
            "summary" => summaries.push(el),
            "og_image" => og_images.push(el),
            "og_description" => og_descriptions.push(el),
            _ => {}
        }
    }

    Ok(PresentationElements { titles, subtitles, summaries, og_images, og_descriptions })
}

/// Hent presentasjonselementer for flere artikler i én spørring.
/// Returnerer et HashMap fra artikkel-ID til PresentationElements.
async fn fetch_presentation_elements_batch(
    db: &PgPool,
    article_ids: &[Uuid],
) -> Result<HashMap<Uuid, PresentationElements>, sqlx::Error> {
    if article_ids.is_empty() {
        return Ok(HashMap::new());
    }

    let rows: Vec<(Uuid, Uuid, String, Option<String>, Option<String>, String, serde_json::Value, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT e.target_id AS article_id, e.id AS edge_id, e.edge_type, n.title, n.content, n.node_kind, n.metadata, e.metadata AS edge_metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = ANY($1)
          AND e.edge_type IN ('title', 'subtitle', 'summary', 'og_image', 'og_description')
        ORDER BY e.created_at
        "#,
    )
    .bind(article_ids)
    .fetch_all(db)
    .await?;

    let mut map: HashMap<Uuid, PresentationElements> = HashMap::new();

    for (article_id, edge_id, edge_type, title, content, node_kind, metadata, edge_metadata) in rows {
        let el = PresEl { edge_id, title, content, node_kind, metadata, edge_metadata };
        let pres = map.entry(article_id).or_insert_with(|| PresentationElements {
            titles: vec![], subtitles: vec![], summaries: vec![],
            og_images: vec![], og_descriptions: vec![],
        });
        match edge_type.as_str() {
            "title" => pres.titles.push(el),
            "subtitle" => pres.subtitles.push(el),
            "summary" => pres.summaries.push(el),
            "og_image" => pres.og_images.push(el),
            "og_description" => pres.og_descriptions.push(el),
            _ => {}
        }
    }

    Ok(map)
}

fn truncate(s: &str, max: usize) -> String {
    if s.chars().count() <= max {
        return s.to_string();
    }
    // Finn char-boundary for maks lengde
    let byte_pos = s.char_indices()
        .nth(max)
        .map(|(i, _)| i)
        .unwrap_or(s.len());
    // Finn siste mellomrom før grensen
    match s[..byte_pos].rfind(' ') {
        Some(pos) => format!("{}…", &s[..pos]),
        None => format!("{}…", &s[..byte_pos]),
    }
}

// =============================================================================
// HTTP-handlers
// =============================================================================

/// GET /pub/{slug} — forside for en publikasjon.
///
/// Støtter to moduser styrt av `index_mode` i trait-konfig:
/// - **static**: Serverer pre-rendret HTML fra CAS (immutable cache).
///   Forsiden rendres til CAS via `render_index`-jobb ved publisering.
/// - **dynamic** (default): Rendrer on-the-fly med in-memory cache.
///   TTL styres av `index_cache_ttl` (default 300s).
pub async fn serve_index(
    State(state): State<AppState>,
    Path(slug): Path<String>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    let index_mode = collection.publishing_config.index_mode.as_deref().unwrap_or("dynamic");
    let cache_ttl = collection.publishing_config.index_cache_ttl.unwrap_or(300);

    // --- Statisk modus: server fra CAS ---
    if index_mode == "static" {
        // Sjekk metadata.rendered_index.index_hash
        let hash_row: Option<(serde_json::Value,)> = sqlx::query_as(
            "SELECT metadata FROM nodes WHERE id = $1",
        )
        .bind(collection.id)
        .fetch_optional(&state.db)
        .await
        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

        if let Some((metadata,)) = hash_row {
            if let Some(index_hash) = metadata
                .get("rendered_index")
                .and_then(|r| r.get("index_hash"))
                .and_then(|h| h.as_str())
            {
                let cas_path = state.cas.path_for(index_hash);
                if cas_path.exists() {
                    let html_bytes = tokio::fs::read(&cas_path).await.map_err(|e| {
                        tracing::error!(hash = %index_hash, error = %e, "Kunne ikke lese CAS-fil for index");
                        StatusCode::INTERNAL_SERVER_ERROR
                    })?;

                    return Ok(Response::builder()
                        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
                        .header(
                            header::CACHE_CONTROL,
                            "public, max-age=31536000, immutable",
                        )
                        .body(html_bytes.into())
                        .unwrap());
                }
            }
        }

        // Fallthrough: ingen CAS-versjon — render on-the-fly som fallback
        tracing::warn!(slug = %slug, "Statisk index mangler i CAS, faller tilbake til dynamisk rendering");
    }

    // --- Dynamisk modus: in-memory cache med TTL ---
    {
        let cache = state.index_cache.read().await;
        if let Some(cached) = cache.get(&collection.id) {
            if cached.expires_at > Utc::now() {
                // Log A/B-impressions asynkront ved cache-hit
                if !cached.active_ab_variants.is_empty() {
                    let db_clone = state.db.clone();
                    let cid = collection.id;
                    let variants = cached.active_ab_variants.clone();
                    tokio::spawn(async move {
                        log_ab_impressions(&db_clone, cid, &variants).await;
                    });
                }

                let max_age = (cached.expires_at - Utc::now()).num_seconds().max(0);
                return Ok(Response::builder()
                    .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
                    .header(
                        header::CACHE_CONTROL,
                        format!("public, max-age={max_age}"),
                    )
                    .body(cached.html.clone().into())
                    .unwrap());
            }
        }
    }

    // Cache miss eller utløpt — render og cache
    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = collection.publishing_config.theme_config.clone();
    let featured_max = collection.publishing_config.featured_max.unwrap_or(4);
    let stream_page_size = collection.publishing_config.stream_page_size.unwrap_or(20);

    let (hero, featured, stream, ab_variants) = fetch_index_articles_optimized(
        &state.db,
        collection.id,
        featured_max,
        stream_page_size,
    )
    .await
    .map_err(|e| {
        tracing::error!(slug = %slug, error = %e, "Feil ved henting av forsideartikler");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection
        .publishing_config
        .custom_domain
        .as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let index_data = IndexData {
        title: collection_title,
        description: None,
        hero,
        featured,
        stream,
    };

    let tera = build_tera();
    let html = render_index(&tera, theme, &config, &index_data, &base_url, collection.has_rss).map_err(|e| {
        tracing::error!(slug = %slug, theme = %theme, error = %e, "Tera render-feil (index)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    // Log A/B-impressions asynkront (fire-and-forget)
    if !ab_variants.is_empty() {
        let db_clone = state.db.clone();
        let cid = collection.id;
        let variants = ab_variants.clone();
        tokio::spawn(async move {
            log_ab_impressions(&db_clone, cid, &variants).await;
        });
    }

    // Legg i cache med aktive A/B-varianter (for impression-logging)
    let expires_at = Utc::now() + chrono::Duration::seconds(cache_ttl as i64);
    {
        let mut cache = state.index_cache.write().await;
        cache.insert(collection.id, CachedIndex {
            html: html.clone(),
            expires_at,
            active_ab_variants: ab_variants,
        });
    }

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(
            header::CACHE_CONTROL,
            format!("public, max-age={cache_ttl}"),
        )
        .body(html.into())
        .unwrap())
}

/// GET /pub/{slug}/{article_id} — enkeltartikkel.
///
/// Serverer fra CAS hvis artikkelen er pre-rendret (metadata.rendered.html_hash).
/// Faller tilbake til on-the-fly rendering hvis ikke.
pub async fn serve_article(
    State(state): State<AppState>,
    Path((slug, article_id)): Path<(String, String)>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &collection.publishing_config.theme_config;

    let fetched = fetch_article(&state.db, collection.id, &article_id)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, article = %article_id, error = %e, "Feil ved henting av artikkel");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    // A/B klikk-attribusjon er håndtert via track_click-endepunktet
    // (/pub/{slug}/t/{short_id}?v={edge_id}) som logger klikk for
    // den spesifikke varianten brukeren så. Direkte artikkelvisninger
    // uten variant-parameter logges ikke — dette forhindrer at
    // klikk attribueres feil variant.

    // Sjekk om pre-rendret HTML finnes i CAS
    if let Some(ref hash) = fetched.html_hash {
        let cas_path = state.cas.path_for(hash);
        if cas_path.exists() {
            let html_bytes = tokio::fs::read(&cas_path).await.map_err(|e| {
                tracing::error!(hash = %hash, error = %e, "Kunne ikke lese CAS-fil");
                StatusCode::INTERNAL_SERVER_ERROR
            })?;

            return Ok(Response::builder()
                .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
                .header(
                    header::CACHE_CONTROL,
                    "public, max-age=31536000, immutable",
                )
                .body(html_bytes.into())
                .unwrap());
        }
    }

    // Fallback: render on-the-fly
    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection
        .publishing_config
        .custom_domain
        .as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let canonical_url = format!("{base_url}/{}", fetched.article.short_id);
    let seo = build_seo_data(&fetched.article, &collection_title, &canonical_url);

    let tera = build_tera();
    let html = render_article(&tera, theme, config, &fetched.article, &collection_title, &base_url, &seo, collection.has_rss)
        .map_err(|e| {
            tracing::error!(slug = %slug, article = %article_id, theme = %theme, error = %e, "Tera render-feil (artikkel)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, "public, max-age=300")
        .body(html.into())
        .unwrap())
}

/// GET /pub/{slug}/preview/{theme} — forhåndsvisning av tema med testdata.
/// Nyttig for å se hvordan et tema ser ut uten reelle data.
pub async fn preview_theme(
    Path((slug, theme)): Path<(String, String)>,
) -> Result<Response, StatusCode> {
    let valid_themes = ["avis", "magasin", "blogg", "tidsskrift"];
    if !valid_themes.contains(&theme.as_str()) {
        return Err(StatusCode::NOT_FOUND);
    }

    let config = ThemeConfig::default();

    let sample_articles: Vec<ArticleData> = (1..=6)
        .map(|i| ArticleData {
            id: format!("00000000-0000-0000-0000-00000000000{i}"),
            short_id: format!("0000000{i}"),
            title: format!("Eksempelartikkel {i}"),
            subtitle: None,
            content: "Lorem ipsum dolor sit amet, consectetur adipiscing elit. \
                Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. \
                Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris."
                .to_string(),
            summary: Some("Lorem ipsum dolor sit amet, consectetur adipiscing elit.".to_string()),
            og_image: None,
            published_at: "2026-03-18T12:00:00Z".to_string(),
            published_at_short: "18. mars 2026".to_string(),
        })
        .collect();

    let index_data = IndexData {
        title: format!("Forhåndsvisning — {theme}"),
        description: Some("Eksempeldata for temavisning".to_string()),
        hero: Some(sample_articles[0].clone()),
        featured: sample_articles[1..4].to_vec(),
        stream: sample_articles[4..].to_vec(),
    };

    let base_url = format!("/pub/{slug}");

    let tera = build_tera();
    let html = render_index(&tera, &theme, &config, &index_data, &base_url, false).map_err(|e| {
        tracing::error!(theme = %theme, error = %e, "Tera render-feil (preview)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, "no-cache")
        .body(html.into())
        .unwrap())
}

// =============================================================================
// Planlagt publisering — periodisk scheduler
// =============================================================================

/// Rad fra spørring for planlagte artikler som er klare for publisering.
#[derive(sqlx::FromRow, Debug)]
struct ScheduledArticle {
    node_id: Uuid,
    collection_id: Uuid,
}

/// Finn belongs_to-edges med publish_at i fortiden der artikkelen
/// ikke er rendret ennå. Returnerer (node_id, collection_id)-par.
async fn find_due_articles(db: &PgPool) -> Result<Vec<ScheduledArticle>, sqlx::Error> {
    // En artikkel er "due" når:
    // 1. belongs_to-edge har publish_at <= now()
    // 2. Noden mangler metadata.rendered.html_hash (ikke rendret)
    //
    // Vi sjekker også at det ikke allerede finnes en pending/running
    // render_article-jobb for denne noden, for å unngå duplikater.
    sqlx::query_as::<_, ScheduledArticle>(
        r#"
        SELECT
            e.source_id AS node_id,
            e.target_id AS collection_id
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.edge_type = 'belongs_to'
          AND (e.metadata->>'publish_at')::timestamptz <= now()
          AND (
            n.metadata->'rendered'->>'html_hash' IS NULL
          )
          AND NOT EXISTS (
            SELECT 1 FROM job_queue jq
            WHERE jq.job_type = 'render_article'
              AND jq.status IN ('pending', 'running', 'retry')
              AND jq.payload->>'node_id' = n.id::text
          )
        "#,
    )
    .fetch_all(db)
    .await
}

/// Kjør én runde med planlagt publisering.
/// Returnerer antall artikler som ble lagt i render-kø.
async fn run_publish_scheduler(db: &PgPool) -> Result<usize, String> {
    let due = find_due_articles(db)
        .await
        .map_err(|e| format!("Spørring for planlagte artikler feilet: {e}"))?;

    if due.is_empty() {
        return Ok(0);
    }

    tracing::info!(count = due.len(), "Fant planlagte artikler klare for publisering");

    // Samle unike collection_ids for index-oppdatering etterpå
    let mut collections_to_reindex: std::collections::HashSet<Uuid> = std::collections::HashSet::new();

    for article in &due {
        let payload = serde_json::json!({
            "node_id": article.node_id.to_string(),
            "collection_id": article.collection_id.to_string(),
        });

        match jobs::enqueue(db, "render_article", payload, Some(article.collection_id), 5).await {
            Ok(job_id) => {
                tracing::info!(
                    job_id = %job_id,
                    node_id = %article.node_id,
                    collection_id = %article.collection_id,
                    "Render-jobb opprettet for planlagt artikkel"
                );
                collections_to_reindex.insert(article.collection_id);
            }
            Err(e) => {
                tracing::error!(
                    node_id = %article.node_id,
                    error = %e,
                    "Kunne ikke opprette render-jobb for planlagt artikkel"
                );
            }
        }
    }

    // Legg inn render_index-jobb for hver berørt samling (lavere prioritet)
    for collection_id in &collections_to_reindex {
        let payload = serde_json::json!({
            "collection_id": collection_id.to_string(),
        });

        if let Err(e) = jobs::enqueue(db, "render_index", payload, Some(*collection_id), 3).await {
            tracing::error!(
                collection_id = %collection_id,
                error = %e,
                "Kunne ikke opprette render_index-jobb"
            );
        }
    }

    let count = due.len();
    tracing::info!(
        articles = count,
        collections = collections_to_reindex.len(),
        "Planlagt publisering: jobber lagt i kø"
    );

    Ok(count)
}

/// Start periodisk scheduler for planlagt publisering.
/// Sjekker hvert 60. sekund for artikler med publish_at i fortiden.
pub fn start_publish_scheduler(db: PgPool) {
    tokio::spawn(async move {
        // Vent 30 sekunder etter oppstart før første sjekk
        tokio::time::sleep(std::time::Duration::from_secs(30)).await;
        tracing::info!("Planlagt publisering-scheduler startet (intervall: 60s)");

        loop {
            match run_publish_scheduler(&db).await {
                Ok(count) => {
                    if count > 0 {
                        tracing::info!(
                            articles = count,
                            "Planlagt publisering: {} artikler lagt i render-kø",
                            count,
                        );
                    }
                }
                Err(e) => {
                    tracing::error!(error = %e, "Planlagt publisering-scheduler feilet");
                }
            }

            tokio::time::sleep(std::time::Duration::from_secs(60)).await;
        }
    });
}

// =============================================================================
// Bulk re-rendering ved temaendring (oppgave 14.14)
// =============================================================================

/// Paginert batch-jobb: finn artikler som trenger re-rendering og enqueue
/// render_article-jobber i grupper på 100. Artikler serveres med gammelt
/// tema til de er re-rendret — renderer_version i metadata identifiserer
/// hvilke som gjenstår.
///
/// Kalles når theme eller theme_config endres på en samling.
pub async fn trigger_bulk_rerender(
    db: &PgPool,
    collection_id: Uuid,
) -> Result<usize, String> {
    let batch_size: i64 = 100;
    let mut total_enqueued: usize = 0;

    loop {
        // Finn neste batch artikler som trenger re-rendering.
        // Filtrerer ut artikler som allerede har pending/running render-jobb.
        let article_ids: Vec<(Uuid,)> = sqlx::query_as(
            r#"
            SELECT e.source_id
            FROM edges e
            JOIN nodes n ON n.id = e.source_id
            WHERE e.target_id = $1
              AND e.edge_type = 'belongs_to'
              AND (
                  n.metadata->'rendered'->>'renderer_version' IS NULL
                  OR (n.metadata->'rendered'->>'renderer_version')::bigint < $2
              )
              AND NOT EXISTS (
                  SELECT 1 FROM job_queue jq
                  WHERE jq.job_type = 'render_article'
                    AND jq.status IN ('pending', 'running', 'retry')
                    AND jq.payload->>'node_id' = n.id::text
              )
            LIMIT $3
            "#,
        )
        .bind(collection_id)
        .bind(RENDERER_VERSION)
        .bind(batch_size)
        .fetch_all(db)
        .await
        .map_err(|e| format!("Feil ved henting av artikler for bulk rerender: {e}"))?;

        if article_ids.is_empty() {
            break;
        }

        let batch_count = article_ids.len();

        for (article_id,) in &article_ids {
            let payload = serde_json::json!({
                "node_id": article_id.to_string(),
                "collection_id": collection_id.to_string(),
            });
            if let Err(e) = jobs::enqueue(db, "render_article", payload, Some(collection_id), 3).await {
                tracing::error!(
                    article_id = %article_id,
                    collection_id = %collection_id,
                    error = %e,
                    "Kunne ikke enqueue render_article ved temaendring"
                );
            }
        }

        total_enqueued += batch_count;

        tracing::info!(
            collection_id = %collection_id,
            batch = batch_count,
            total = total_enqueued,
            "Bulk rerender batch enqueued"
        );

        // Hvis batchen var mindre enn batch_size, er vi ferdige
        if (batch_count as i64) < batch_size {
            break;
        }
    }

    // Enqueue render av forsiden til slutt (lavere prioritet)
    let index_payload = serde_json::json!({
        "collection_id": collection_id.to_string(),
    });
    if let Err(e) = jobs::enqueue(db, "render_index", index_payload, Some(collection_id), 4).await {
        tracing::error!(
            collection_id = %collection_id,
            error = %e,
            "Kunne ikke enqueue render_index ved temaendring"
        );
    }

    tracing::info!(
        collection_id = %collection_id,
        total_articles = total_enqueued,
        "Bulk re-rendering enqueued ved temaendring"
    );

    Ok(total_enqueued)
}

// =============================================================================
// Dynamiske sider: kategori, arkiv, søk, om-side (oppgave 14.15)
// =============================================================================

/// Cachet dynamisk side med utløpstid. Nøkkel er (collection_id, side-type + params).
pub struct CachedDynamicPage {
    html: String,
    expires_at: DateTime<Utc>,
}

/// Thread-safe cache for dynamiske sider (kategori, arkiv, søk).
pub type DynamicPageCache = Arc<RwLock<HashMap<String, CachedDynamicPage>>>;

pub fn new_dynamic_page_cache() -> DynamicPageCache {
    Arc::new(RwLock::new(HashMap::new()))
}

/// Sjekk cache og returner HTML hvis gyldig.
async fn check_dynamic_cache(cache: &DynamicPageCache, key: &str) -> Option<String> {
    let map = cache.read().await;
    if let Some(cached) = map.get(key) {
        if cached.expires_at > Utc::now() {
            return Some(cached.html.clone());
        }
    }
    None
}

/// Sett inn i dynamisk cache.
async fn insert_dynamic_cache(cache: &DynamicPageCache, key: String, html: String, ttl_secs: u64) {
    let expires_at = Utc::now() + chrono::Duration::seconds(ttl_secs as i64);
    let mut map = cache.write().await;
    map.insert(key, CachedDynamicPage { html, expires_at });
}

const DYNAMIC_PAGE_SIZE: i64 = 20;

/// Beregn sideområde for paginering (maks 7 sider rundt gjeldende).
fn page_range(current: i64, total: i64) -> Vec<i64> {
    let start = (current - 3).max(1);
    let end = (current + 3).min(total);
    (start..=end).collect()
}

/// Norsk månedsnavn.
fn norwegian_month(month: u32) -> &'static str {
    match month {
        1 => "januar", 2 => "februar", 3 => "mars", 4 => "april",
        5 => "mai", 6 => "juni", 7 => "juli", 8 => "august",
        9 => "september", 10 => "oktober", 11 => "november",
        12 => "desember", _ => "ukjent",
    }
}

#[derive(Deserialize)]
pub struct PageQuery {
    pub side: Option<i64>,
}

#[derive(Deserialize)]
pub struct SearchQuery {
    pub q: Option<String>,
    pub side: Option<i64>,
}

// --- Kategori-side ---

/// GET /pub/{slug}/kategori/{tag} — artikler filtrert på tag-edge.
///
/// Tag-edges: edge_type = 'tagged' fra artikkel → tag-node.
/// Tag-noder har node_kind = 'tag'. Slug-matching på tag-nodens title (lowercased).
pub async fn serve_category(
    State(state): State<AppState>,
    Path((slug, tag_slug)): Path<(String, String)>,
    Query(query): Query<PageQuery>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling (kategori)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    let page = query.side.unwrap_or(1).max(1);
    let cache_ttl = collection.publishing_config.index_cache_ttl.unwrap_or(300);

    // Cache-nøkkel
    let cache_key = format!("cat:{}:{}:{}", collection.id, tag_slug, page);

    if let Some(html) = check_dynamic_cache(&state.dynamic_page_cache, &cache_key).await {
        return Ok(Response::builder()
            .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
            .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
            .body(html.into())
            .unwrap());
    }

    // Finn tag-noden via title match (case-insensitive)
    let tag_row: Option<(Uuid, Option<String>)> = sqlx::query_as(
        r#"
        SELECT id, title FROM nodes
        WHERE node_kind = 'tag' AND LOWER(title) = LOWER($1)
        LIMIT 1
        "#,
    )
    .bind(&tag_slug)
    .fetch_optional(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let Some((tag_id, tag_title)) = tag_row else {
        return Err(StatusCode::NOT_FOUND);
    };
    let tag_name = tag_title.unwrap_or_else(|| tag_slug.clone());

    // Tell totalt antall artikler med denne taggen i samlingen
    // Ekskluderer artikler med fremtidig publish_at
    let (total_count,): (i64,) = sqlx::query_as(
        r#"
        SELECT COUNT(*)
        FROM edges e_belongs
        JOIN edges e_tag ON e_tag.source_id = e_belongs.source_id
        WHERE e_belongs.target_id = $1
          AND e_belongs.edge_type = 'belongs_to'
          AND e_tag.target_id = $2
          AND e_tag.edge_type = 'tagged'
          AND (e_belongs.metadata->>'publish_at' IS NULL
               OR (e_belongs.metadata->>'publish_at')::timestamptz <= now())
        "#,
    )
    .bind(collection.id)
    .bind(tag_id)
    .fetch_one(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let total_pages = ((total_count as f64) / DYNAMIC_PAGE_SIZE as f64).ceil() as i64;
    let offset = (page - 1) * DYNAMIC_PAGE_SIZE;

    type Row = (Uuid, Option<String>, Option<String>, DateTime<Utc>, Option<serde_json::Value>);

    let rows: Vec<Row> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.created_at, e_belongs.metadata
        FROM edges e_belongs
        JOIN edges e_tag ON e_tag.source_id = e_belongs.source_id
        JOIN nodes n ON n.id = e_belongs.source_id
        WHERE e_belongs.target_id = $1
          AND e_belongs.edge_type = 'belongs_to'
          AND e_tag.target_id = $2
          AND e_tag.edge_type = 'tagged'
          AND (e_belongs.metadata->>'publish_at' IS NULL
               OR (e_belongs.metadata->>'publish_at')::timestamptz <= now())
        ORDER BY COALESCE(
            (e_belongs.metadata->>'publish_at')::timestamptz,
            n.created_at
        ) DESC
        LIMIT $3 OFFSET $4
        "#,
    )
    .bind(collection.id)
    .bind(tag_id)
    .bind(DYNAMIC_PAGE_SIZE)
    .bind(offset)
    .fetch_all(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let articles: Vec<ArticleData> = rows.into_iter().map(|(id, title, content, created_at, edge_meta)| {
        let publish_at = edge_meta.as_ref()
            .and_then(|m| m.get("publish_at"))
            .and_then(|v| v.as_str())
            .and_then(|s| s.parse::<DateTime<Utc>>().ok())
            .unwrap_or(created_at);
        let summary = content.as_deref().map(|c| truncate(c, 200));
        ArticleData {
            id: id.to_string(),
            short_id: id.to_string()[..8].to_string(),
            title: title.unwrap_or_else(|| "Uten tittel".to_string()),
            subtitle: None,
            content: content.unwrap_or_default(),
            summary,
            og_image: None,
            published_at: publish_at.to_rfc3339(),
            published_at_short: publish_at.format("%e. %B %Y").to_string(),
        }
    }).collect();

    // Render
    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &collection.publishing_config.theme_config;
    let css_vars = build_css_variables(theme, config);
    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection.publishing_config.custom_domain.as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let tera = build_tera();
    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("collection_title", &collection_title);
    ctx.insert("base_url", &base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &collection.has_rss);
    ctx.insert("tag_name", &tag_name);
    ctx.insert("tag_slug", &tag_slug);
    ctx.insert("articles", &articles);
    ctx.insert("article_count", &total_count);
    ctx.insert("current_page", &page);
    ctx.insert("total_pages", &total_pages);
    ctx.insert("page_range", &page_range(page, total_pages));

    let html = tera.render("category.html", &ctx).map_err(|e| {
        tracing::error!(error = %e, "Tera render-feil (category)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    insert_dynamic_cache(&state.dynamic_page_cache, cache_key, html.clone(), cache_ttl).await;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
        .body(html.into())
        .unwrap())
}

// --- Arkiv-side ---

#[derive(Serialize)]
struct MonthGroup {
    label: String,
    articles: Vec<ArticleData>,
}

/// GET /pub/{slug}/arkiv — kronologisk arkiv med månedsgruppering.
pub async fn serve_archive(
    State(state): State<AppState>,
    Path(slug): Path<String>,
    Query(query): Query<PageQuery>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling (arkiv)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    let page = query.side.unwrap_or(1).max(1);
    let cache_ttl = collection.publishing_config.index_cache_ttl.unwrap_or(300);
    let cache_key = format!("archive:{}:{}", collection.id, page);

    if let Some(html) = check_dynamic_cache(&state.dynamic_page_cache, &cache_key).await {
        return Ok(Response::builder()
            .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
            .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
            .body(html.into())
            .unwrap());
    }

    // Tell totalt (ekskluder fremtidige artikler)
    let (total_count,): (i64,) = sqlx::query_as(
        r#"
        SELECT COUNT(*)
        FROM edges e
        WHERE e.target_id = $1 AND e.edge_type = 'belongs_to'
          AND (e.metadata->>'publish_at' IS NULL
               OR (e.metadata->>'publish_at')::timestamptz <= now())
        "#,
    )
    .bind(collection.id)
    .fetch_one(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let total_pages = ((total_count as f64) / DYNAMIC_PAGE_SIZE as f64).ceil() as i64;
    let offset = (page - 1) * DYNAMIC_PAGE_SIZE;

    type Row = (Uuid, Option<String>, Option<String>, DateTime<Utc>, Option<serde_json::Value>);

    let rows: Vec<Row> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.created_at, e.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND (e.metadata->>'publish_at' IS NULL
               OR (e.metadata->>'publish_at')::timestamptz <= now())
        ORDER BY COALESCE(
            (e.metadata->>'publish_at')::timestamptz,
            n.created_at
        ) DESC
        LIMIT $2 OFFSET $3
        "#,
    )
    .bind(collection.id)
    .bind(DYNAMIC_PAGE_SIZE)
    .bind(offset)
    .fetch_all(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    // Grupper artikler etter måned
    let mut month_groups: Vec<MonthGroup> = Vec::new();

    for (id, title, content, created_at, edge_meta) in rows {
        let publish_at = edge_meta.as_ref()
            .and_then(|m| m.get("publish_at"))
            .and_then(|v| v.as_str())
            .and_then(|s| s.parse::<DateTime<Utc>>().ok())
            .unwrap_or(created_at);

        let label = format!("{} {}", norwegian_month(publish_at.month()), publish_at.year());
        let summary = content.as_deref().map(|c| truncate(c, 200));

        let article = ArticleData {
            id: id.to_string(),
            short_id: id.to_string()[..8].to_string(),
            title: title.unwrap_or_else(|| "Uten tittel".to_string()),
            subtitle: None,
            content: content.unwrap_or_default(),
            summary,
            og_image: None,
            published_at: publish_at.to_rfc3339(),
            published_at_short: publish_at.format("%e. %B %Y").to_string(),
        };

        if let Some(last) = month_groups.last_mut() {
            if last.label == label {
                last.articles.push(article);
                continue;
            }
        }
        month_groups.push(MonthGroup {
            label,
            articles: vec![article],
        });
    }

    // Render
    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &collection.publishing_config.theme_config;
    let css_vars = build_css_variables(theme, config);
    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection.publishing_config.custom_domain.as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let tera = build_tera();
    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("collection_title", &collection_title);
    ctx.insert("base_url", &base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &collection.has_rss);
    ctx.insert("month_groups", &month_groups);
    ctx.insert("total_articles", &total_count);
    ctx.insert("current_page", &page);
    ctx.insert("total_pages", &total_pages);
    ctx.insert("page_range", &page_range(page, total_pages));

    let html = tera.render("archive.html", &ctx).map_err(|e| {
        tracing::error!(error = %e, "Tera render-feil (archive)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    insert_dynamic_cache(&state.dynamic_page_cache, cache_key, html.clone(), cache_ttl).await;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
        .body(html.into())
        .unwrap())
}

// --- Søk-side ---

/// GET /pub/{slug}/sok?q=...&side=1 — fulltekstsøk i publiserte artikler.
///
/// Bruker PostgreSQL tsvector + ts_rank for relevanssortering.
/// Kun artikler med belongs_to-edge til samlingen inkluderes.
pub async fn serve_search(
    State(state): State<AppState>,
    Path(slug): Path<String>,
    Query(query): Query<SearchQuery>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling (søk)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    let search_query = query.q.unwrap_or_default().trim().to_string();
    let page = query.side.unwrap_or(1).max(1);
    let cache_ttl = collection.publishing_config.index_cache_ttl.unwrap_or(300).min(60); // Kortere cache for søk

    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &collection.publishing_config.theme_config;
    let css_vars = build_css_variables(theme, config);
    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection.publishing_config.custom_domain.as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let tera = build_tera();
    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("collection_title", &collection_title);
    ctx.insert("base_url", &base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &collection.has_rss);
    ctx.insert("query", &search_query);

    if search_query.is_empty() {
        // Vis tom søkeside
        ctx.insert("articles", &Vec::<ArticleData>::new());
        ctx.insert("result_count", &0i64);
        ctx.insert("current_page", &1i64);
        ctx.insert("total_pages", &0i64);
        ctx.insert("page_range", &Vec::<i64>::new());
    } else {
        // Cache-oppslag
        let cache_key = format!("search:{}:{}:{}", collection.id, search_query, page);

        if let Some(html) = check_dynamic_cache(&state.dynamic_page_cache, &cache_key).await {
            return Ok(Response::builder()
                .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
                .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
                .body(html.into())
                .unwrap());
        }

        // Konverter søkeord til tsquery (bruk plainto_tsquery for sikkerhet)
        let (total_count,): (i64,) = sqlx::query_as(
            r#"
            SELECT COUNT(*)
            FROM edges e
            JOIN nodes n ON n.id = e.source_id
            WHERE e.target_id = $1
              AND e.edge_type = 'belongs_to'
              AND n.search_vector @@ plainto_tsquery('norwegian', $2)
              AND (e.metadata->>'publish_at' IS NULL
                   OR (e.metadata->>'publish_at')::timestamptz <= now())
            "#,
        )
        .bind(collection.id)
        .bind(&search_query)
        .fetch_one(&state.db)
        .await
        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

        let total_pages = ((total_count as f64) / DYNAMIC_PAGE_SIZE as f64).ceil() as i64;
        let offset = (page - 1) * DYNAMIC_PAGE_SIZE;

        type Row = (Uuid, Option<String>, Option<String>, DateTime<Utc>, Option<serde_json::Value>);

        let rows: Vec<Row> = sqlx::query_as(
            r#"
            SELECT n.id, n.title, n.content, n.created_at, e.metadata
            FROM edges e
            JOIN nodes n ON n.id = e.source_id
            WHERE e.target_id = $1
              AND e.edge_type = 'belongs_to'
              AND n.search_vector @@ plainto_tsquery('norwegian', $2)
              AND (e.metadata->>'publish_at' IS NULL
                   OR (e.metadata->>'publish_at')::timestamptz <= now())
            ORDER BY ts_rank(n.search_vector, plainto_tsquery('norwegian', $2)) DESC
            LIMIT $3 OFFSET $4
            "#,
        )
        .bind(collection.id)
        .bind(&search_query)
        .bind(DYNAMIC_PAGE_SIZE)
        .bind(offset)
        .fetch_all(&state.db)
        .await
        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

        let articles: Vec<ArticleData> = rows.into_iter().map(|(id, title, content, created_at, edge_meta)| {
            let publish_at = edge_meta.as_ref()
                .and_then(|m| m.get("publish_at"))
                .and_then(|v| v.as_str())
                .and_then(|s| s.parse::<DateTime<Utc>>().ok())
                .unwrap_or(created_at);
            let summary = content.as_deref().map(|c| truncate(c, 200));
            ArticleData {
                id: id.to_string(),
                short_id: id.to_string()[..8].to_string(),
                title: title.unwrap_or_else(|| "Uten tittel".to_string()),
                subtitle: None,
                content: content.unwrap_or_default(),
                summary,
                og_image: None,
                published_at: publish_at.to_rfc3339(),
                published_at_short: publish_at.format("%e. %B %Y").to_string(),
            }
        }).collect();

        ctx.insert("articles", &articles);
        ctx.insert("result_count", &total_count);
        ctx.insert("current_page", &page);
        ctx.insert("total_pages", &total_pages);
        ctx.insert("page_range", &page_range(page, total_pages));

        let html = tera.render("search.html", &ctx).map_err(|e| {
            tracing::error!(error = %e, "Tera render-feil (search)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?;

        insert_dynamic_cache(&state.dynamic_page_cache, cache_key, html.clone(), cache_ttl).await;

        return Ok(Response::builder()
            .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
            .header(header::CACHE_CONTROL, format!("public, max-age={cache_ttl}"))
            .body(html.into())
            .unwrap());
    }

    let html = tera.render("search.html", &ctx).map_err(|e| {
        tracing::error!(error = %e, "Tera render-feil (search)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, "no-cache")
        .body(html.into())
        .unwrap())
}

// --- Om-side ---

/// GET /pub/{slug}/om — statisk om-side.
///
/// Om-siden er en node med `page_role: "about"` i metadata, koblet til
/// samlingen via `belongs_to`-edge. Rendret HTML hentes fra CAS
/// (metadata.rendered.html_hash) eller rendres on-the-fly via about-template.
pub async fn serve_about(
    State(state): State<AppState>,
    Path(slug): Path<String>,
) -> Result<Response, StatusCode> {
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|e| {
            tracing::error!(slug = %slug, error = %e, "Feil ved oppslag av samling (om)");
            StatusCode::INTERNAL_SERVER_ERROR
        })?
        .ok_or(StatusCode::NOT_FOUND)?;

    // Finn om-noden: belongs_to samlingen med page_role = "about"
    let about_row: Option<(Uuid, Option<String>, Option<String>, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT n.id, n.title, n.content, n.metadata
        FROM edges e
        JOIN nodes n ON n.id = e.source_id
        WHERE e.target_id = $1
          AND e.edge_type = 'belongs_to'
          AND n.metadata->>'page_role' = 'about'
        LIMIT 1
        "#,
    )
    .bind(collection.id)
    .fetch_optional(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let Some((_id, _title, content, metadata)) = about_row else {
        return Err(StatusCode::NOT_FOUND);
    };

    // Sjekk om rendret HTML finnes i CAS
    if let Some(html_hash) = metadata
        .get("rendered")
        .and_then(|r| r.get("html_hash"))
        .and_then(|h| h.as_str())
    {
        let cas_path = state.cas.path_for(html_hash);
        if cas_path.exists() {
            let html_bytes = tokio::fs::read(&cas_path).await.map_err(|e| {
                tracing::error!(hash = %html_hash, error = %e, "Kunne ikke lese CAS-fil (about)");
                StatusCode::INTERNAL_SERVER_ERROR
            })?;

            return Ok(Response::builder()
                .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
                .header(header::CACHE_CONTROL, "public, max-age=31536000, immutable")
                .body(html_bytes.into())
                .unwrap());
        }
    }

    // Fallback: render on-the-fly via about-template
    let about_html = if let Some(doc) = metadata.get("document") {
        let html = tiptap::document_to_html(doc);
        if html.is_empty() {
            content.unwrap_or_default()
        } else {
            html
        }
    } else {
        content.unwrap_or_default()
    };

    let theme = collection.publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &collection.publishing_config.theme_config;
    let css_vars = build_css_variables(theme, config);
    let collection_title = collection.title.unwrap_or_else(|| slug.clone());
    let base_url = collection.publishing_config.custom_domain.as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let tera = build_tera();
    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("collection_title", &collection_title);
    ctx.insert("base_url", &base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &collection.has_rss);
    ctx.insert("about_html", &about_html);

    let html = tera.render("about.html", &ctx).map_err(|e| {
        tracing::error!(error = %e, "Tera render-feil (about)");
        StatusCode::INTERNAL_SERVER_ERROR
    })?;

    Ok(Response::builder()
        .header(header::CONTENT_TYPE, "text/html; charset=utf-8")
        .header(header::CACHE_CONTROL, "public, max-age=3600")
        .body(html.into())
        .unwrap())
}

/// Render om-side til CAS. Kalles ved opprettelse/oppdatering av om-noden.
pub async fn render_about_to_cas(
    db: &PgPool,
    cas: &CasStore,
    node_id: Uuid,
    collection_id: Uuid,
) -> Result<serde_json::Value, String> {
    // Hent samlingens konfig
    let collection_row: Option<(Option<String>, serde_json::Value)> = sqlx::query_as(
        r#"SELECT title, metadata FROM nodes WHERE id = $1 AND node_kind = 'collection'"#,
    )
    .bind(collection_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av samling: {e}"))?;

    let Some((collection_title_opt, collection_metadata)) = collection_row else {
        return Err(format!("Samling {collection_id} finnes ikke"));
    };

    let traits = collection_metadata.get("traits");
    let publishing_config: PublishingConfig = traits
        .and_then(|t| t.get("publishing"))
        .cloned()
        .map(|v| serde_json::from_value(v).unwrap_or_default())
        .unwrap_or_default();

    let has_rss = traits.and_then(|t| t.get("rss")).is_some();
    let slug = publishing_config.slug.as_deref().unwrap_or("unknown");
    let theme = publishing_config.theme.as_deref().unwrap_or("blogg");
    let config = &publishing_config.theme_config;
    let collection_title = collection_title_opt.unwrap_or_else(|| slug.to_string());

    // Hent om-nodens innhold
    let node_row: Option<(Option<String>, serde_json::Value)> = sqlx::query_as(
        "SELECT content, metadata FROM nodes WHERE id = $1",
    )
    .bind(node_id)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("Feil ved henting av om-node: {e}"))?;

    let Some((content, metadata)) = node_row else {
        return Err(format!("Node {node_id} finnes ikke"));
    };

    let about_html = if let Some(doc) = metadata.get("document") {
        let html = tiptap::document_to_html(doc);
        if html.is_empty() { content.unwrap_or_default() } else { html }
    } else {
        content.unwrap_or_default()
    };

    let css_vars = build_css_variables(theme, config);
    let base_url = publishing_config.custom_domain.as_deref()
        .map(|d| format!("https://{d}"))
        .unwrap_or_else(|| format!("/pub/{slug}"));

    let tera = build_tera();
    let mut ctx = Context::new();
    ctx.insert("css_variables", &css_vars);
    ctx.insert("theme", theme);
    ctx.insert("collection_title", &collection_title);
    ctx.insert("base_url", &base_url);
    ctx.insert("logo_hash", &config.logo_hash);
    ctx.insert("has_rss", &has_rss);
    ctx.insert("about_html", &about_html);

    let html = tera.render("about.html", &ctx)
        .map_err(|e| format!("Tera render-feil (about): {e}"))?;

    let store_result = cas.store(html.as_bytes()).await
        .map_err(|e| format!("CAS-lagring feilet: {e}"))?;

    // Oppdater nodens metadata.rendered
    let now = Utc::now();
    sqlx::query(
        r#"
        UPDATE nodes
        SET metadata = jsonb_set(
            jsonb_set(
                jsonb_set(
                    CASE WHEN metadata ? 'rendered'
                        THEN metadata
                        ELSE jsonb_set(metadata, '{rendered}', '{}'::jsonb)
                    END,
                    '{rendered,html_hash}',
                    to_jsonb($2::text)
                ),
                '{rendered,rendered_at}',
                to_jsonb($3::text)
            ),
            '{rendered,renderer_version}',
            to_jsonb($4::bigint)
        )
        WHERE id = $1
        "#,
    )
    .bind(node_id)
    .bind(&store_result.hash)
    .bind(now.to_rfc3339())
    .bind(RENDERER_VERSION)
    .execute(db)
    .await
    .map_err(|e| format!("Feil ved oppdatering av metadata.rendered (about): {e}"))?;

    Ok(serde_json::json!({
        "html_hash": store_result.hash,
        "size": store_result.size,
        "renderer_version": RENDERER_VERSION
    }))
}

// =============================================================================
// =============================================================================
// A/B-testing: impression-logging, klikk-sporing, evaluering (oppgave 14.17)
// =============================================================================

/// Log impressions for A/B-varianter som vises på forsiden.
/// Kalles asynkront (fire-and-forget) ved forside-serving.
async fn log_ab_impressions(db: &PgPool, collection_id: Uuid, variants: &[(Uuid, Uuid)]) {
    for &(edge_id, article_id) in variants {
        if let Err(e) = sqlx::query(
            r#"
            INSERT INTO ab_events (edge_id, article_id, collection_id, event_type)
            VALUES ($1, $2, $3, 'impression')
            "#,
        )
        .bind(edge_id)
        .bind(article_id)
        .bind(collection_id)
        .execute(db)
        .await
        {
            tracing::warn!(
                edge_id = %edge_id,
                error = %e,
                "Kunne ikke logge A/B-impression"
            );
        }
    }
}

/// Log et klikk for en A/B-variant.
async fn log_ab_click(db: &PgPool, edge_id: Uuid, article_id: Uuid, collection_id: Uuid) {
    if let Err(e) = sqlx::query(
        r#"
        INSERT INTO ab_events (edge_id, article_id, collection_id, event_type)
        VALUES ($1, $2, $3, 'click')
        "#,
    )
    .bind(edge_id)
    .bind(article_id)
    .bind(collection_id)
    .execute(db)
    .await
    {
        tracing::warn!(
            edge_id = %edge_id,
            error = %e,
            "Kunne ikke logge A/B-klikk"
        );
    }
}

/// GET /pub/{slug}/t/{article_short_id} — klikk-sporing for A/B-test.
///
/// Mottar edge_id som query-parameter `v`. Logger klikk og redirecter
/// til den egentlige artikkelsiden.
pub async fn track_click(
    State(state): State<AppState>,
    Path((slug, article_short_id)): Path<(String, String)>,
    Query(params): Query<HashMap<String, String>>,
) -> Result<Response, StatusCode> {
    // Finn samling
    let collection = find_publishing_collection(&state.db, &slug)
        .await
        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?
        .ok_or(StatusCode::NOT_FOUND)?;

    // Hent edge_id fra query-parameter
    if let Some(edge_id_str) = params.get("v") {
        if let Ok(edge_id) = edge_id_str.parse::<Uuid>() {
            // Finn article_id fra short_id
            let pattern = format!("{article_short_id}%");
            let article_id: Option<(Uuid,)> = sqlx::query_as(
                r#"
                SELECT n.id
                FROM edges e
                JOIN nodes n ON n.id = e.source_id
                WHERE e.target_id = $1
                  AND e.edge_type = 'belongs_to'
                  AND n.id::text LIKE $2
                LIMIT 1
                "#,
            )
            .bind(collection.id)
            .bind(&pattern)
            .fetch_optional(&state.db)
            .await
            .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

            if let Some((aid,)) = article_id {
                // Log klikk asynkront
                let db = state.db.clone();
                let cid = collection.id;
                tokio::spawn(async move {
                    log_ab_click(&db, edge_id, aid, cid).await;
                });
            }
        }
    }

    // Redirect til artikkelsiden
    let redirect_url = format!("/pub/{slug}/{article_short_id}");
    Ok(Response::builder()
        .status(StatusCode::FOUND)
        .header(header::LOCATION, redirect_url)
        .header(header::CACHE_CONTROL, "no-cache, no-store")
        .body(Default::default())
        .unwrap())
}

// =============================================================================
// A/B-evaluering: periodisk CTR-beregning og signifikans-testing
// =============================================================================

/// Finn alle aktive A/B-tester (artikler med >1 ikke-retired variant av samme type).
/// Returnerer grupper: (article_id, edge_type, vec<edge_id>).
async fn find_active_ab_tests(db: &PgPool) -> Result<Vec<AbTestGroup>, sqlx::Error> {
    // Finn alle presentasjonselement-edges med ab_status = 'testing' eller uten ab_status
    // der artikkelen har >1 variant av samme type
    let rows: Vec<(Uuid, Uuid, String, serde_json::Value)> = sqlx::query_as(
        r#"
        SELECT e.target_id AS article_id, e.id AS edge_id, e.edge_type, e.metadata
        FROM edges e
        WHERE e.edge_type IN ('title', 'subtitle', 'summary', 'og_image')
          AND (e.metadata->>'ab_status' IS NULL
               OR e.metadata->>'ab_status' = 'testing')
        ORDER BY e.target_id, e.edge_type
        "#,
    )
    .fetch_all(db)
    .await?;

    // Grupper per (article_id, edge_type) og filtrer til de med >1 variant
    let mut groups: HashMap<(Uuid, String), Vec<Uuid>> = HashMap::new();
    for (article_id, edge_id, edge_type, _metadata) in &rows {
        groups
            .entry((*article_id, edge_type.clone()))
            .or_default()
            .push(*edge_id);
    }

    Ok(groups
        .into_iter()
        .filter(|(_, edges)| edges.len() > 1)
        .map(|((article_id, edge_type), edge_ids)| AbTestGroup {
            article_id,
            edge_type,
            edge_ids,
        })
        .collect())
}

struct AbTestGroup {
    article_id: Uuid,
    edge_type: String,
    edge_ids: Vec<Uuid>,
}

/// Hent impression/klikk-tall per edge_id.
async fn fetch_ab_stats(
    db: &PgPool,
    edge_ids: &[Uuid],
) -> Result<HashMap<Uuid, (i64, i64)>, sqlx::Error> {
    // Returnerer (impressions, clicks) per edge_id
    let rows: Vec<(Uuid, String, i64)> = sqlx::query_as(
        r#"
        SELECT edge_id, event_type, COUNT(*) as cnt
        FROM ab_events
        WHERE edge_id = ANY($1)
        GROUP BY edge_id, event_type
        "#,
    )
    .bind(edge_ids)
    .fetch_all(db)
    .await?;

    let mut stats: HashMap<Uuid, (i64, i64)> = HashMap::new();
    for (edge_id, event_type, cnt) in rows {
        let entry = stats.entry(edge_id).or_insert((0, 0));
        match event_type.as_str() {
            "impression" => entry.0 = cnt,
            "click" => entry.1 = cnt,
            _ => {}
        }
    }

    Ok(stats)
}

/// Z-test for to proporsjoner. Returnerer p-verdi (tosidig).
/// p1 = clicks1/impressions1, p2 = clicks2/impressions2.
fn z_test_proportions(imp1: i64, click1: i64, imp2: i64, click2: i64) -> f64 {
    if imp1 < 30 || imp2 < 30 {
        // For lite data for meningsfull test
        return 1.0;
    }

    let n1 = imp1 as f64;
    let n2 = imp2 as f64;
    let p1 = click1 as f64 / n1;
    let p2 = click2 as f64 / n2;

    // Pooled proportion
    let p = (click1 + click2) as f64 / (n1 + n2);
    let q = 1.0 - p;

    let se = (p * q * (1.0 / n1 + 1.0 / n2)).sqrt();
    if se < 1e-12 {
        return 1.0;
    }

    let z = (p1 - p2).abs() / se;

    // Approksimert p-verdi (tosidig) via kumulativ normalfordeling
    // Bruk enkel tilnærming: P(Z > z) ≈ erfc(z / sqrt(2)) / 2
    2.0 * normal_cdf_complement(z)
}

/// Komplementær kumulativ normalfordeling P(Z > z).
/// Abramowitz & Stegun-tilnærming.
fn normal_cdf_complement(z: f64) -> f64 {
    let t = 1.0 / (1.0 + 0.2316419 * z);
    let d = 0.3989423 * (-z * z / 2.0).exp();
    let p = d * t * (0.3193815 + t * (-0.3565638 + t * (1.781478 + t * (-1.821256 + t * 1.330274))));
    p.max(0.0).min(1.0)
}

/// Minimum impressions per variant før evaluering vurderes.
const MIN_IMPRESSIONS_FOR_EVAL: i64 = 100;

/// Signifikansnivå for å erklære vinner.
const SIGNIFICANCE_LEVEL: f64 = 0.05;

/// Evaluer alle aktive A/B-tester og marker vinnere/tapere.
pub async fn evaluate_ab_tests(db: &PgPool) -> Result<usize, String> {
    let groups = find_active_ab_tests(db)
        .await
        .map_err(|e| format!("Feil ved henting av A/B-tester: {e}"))?;

    if groups.is_empty() {
        return Ok(0);
    }

    let mut resolved = 0;

    for group in &groups {
        let stats = fetch_ab_stats(db, &group.edge_ids)
            .await
            .map_err(|e| format!("Feil ved henting av A/B-stats: {e}"))?;

        // Sjekk at alle varianter har nok data
        let all_ready = group.edge_ids.iter().all(|eid| {
            stats.get(eid).map(|(imp, _)| *imp >= MIN_IMPRESSIONS_FOR_EVAL).unwrap_or(false)
        });

        if !all_ready {
            continue;
        }

        // Oppdater edge-metadata med impressions, clicks, ctr
        for &edge_id in &group.edge_ids {
            let (imp, clicks) = stats.get(&edge_id).copied().unwrap_or((0, 0));
            let ctr = if imp > 0 { clicks as f64 / imp as f64 } else { 0.0 };

            if let Err(e) = sqlx::query(
                r#"
                UPDATE edges
                SET metadata = metadata
                    || jsonb_build_object(
                        'impressions', $2::bigint,
                        'clicks', $3::bigint,
                        'ctr', $4::float8
                    )
                WHERE id = $1
                "#,
            )
            .bind(edge_id)
            .bind(imp)
            .bind(clicks)
            .bind(ctr)
            .execute(db)
            .await
            {
                tracing::warn!(edge_id = %edge_id, error = %e, "Kunne ikke oppdatere edge AB-metadata");
            }
        }

        // For par-sammenligning: test alle par og finn om det finnes en klar vinner
        if group.edge_ids.len() == 2 {
            let (imp_a, click_a) = stats.get(&group.edge_ids[0]).copied().unwrap_or((0, 0));
            let (imp_b, click_b) = stats.get(&group.edge_ids[1]).copied().unwrap_or((0, 0));

            let p_value = z_test_proportions(imp_a, click_a, imp_b, click_b);

            if p_value < SIGNIFICANCE_LEVEL {
                let ctr_a = if imp_a > 0 { click_a as f64 / imp_a as f64 } else { 0.0 };
                let ctr_b = if imp_b > 0 { click_b as f64 / imp_b as f64 } else { 0.0 };

                let (winner_id, loser_id) = if ctr_a >= ctr_b {
                    (group.edge_ids[0], group.edge_ids[1])
                } else {
                    (group.edge_ids[1], group.edge_ids[0])
                };

                // Marker vinner
                let _ = sqlx::query(
                    "UPDATE edges SET metadata = metadata || '{\"ab_status\": \"winner\"}' WHERE id = $1",
                )
                .bind(winner_id)
                .execute(db)
                .await;

                // Marker taper som retired
                let _ = sqlx::query(
                    "UPDATE edges SET metadata = metadata || '{\"ab_status\": \"retired\"}' WHERE id = $1",
                )
                .bind(loser_id)
                .execute(db)
                .await;

                tracing::info!(
                    article_id = %group.article_id,
                    edge_type = %group.edge_type,
                    winner = %winner_id,
                    loser = %loser_id,
                    p_value = p_value,
                    "A/B-test avgjort: vinner markert"
                );

                resolved += 1;
            }
        } else {
            // >2 varianter: finn den med høyest CTR og test mot nest-best
            let mut ranked: Vec<(Uuid, f64, i64, i64)> = group.edge_ids.iter().map(|&eid| {
                let (imp, clicks) = stats.get(&eid).copied().unwrap_or((0, 0));
                let ctr = if imp > 0 { clicks as f64 / imp as f64 } else { 0.0 };
                (eid, ctr, imp, clicks)
            }).collect();
            ranked.sort_by(|a, b| b.1.partial_cmp(&a.1).unwrap_or(std::cmp::Ordering::Equal));

            if ranked.len() >= 2 {
                let (best_id, _, best_imp, best_clicks) = ranked[0];
                let (_second_id, _, second_imp, second_clicks) = ranked[1];

                let p_value = z_test_proportions(best_imp, best_clicks, second_imp, second_clicks);

                if p_value < SIGNIFICANCE_LEVEL {
                    // Vinneren er bedre enn alle andre med signifikans
                    let _ = sqlx::query(
                        "UPDATE edges SET metadata = metadata || '{\"ab_status\": \"winner\"}' WHERE id = $1",
                    )
                    .bind(best_id)
                    .execute(db)
                    .await;

                    // Retire alle andre
                    for &(eid, _, _, _) in &ranked[1..] {
                        let _ = sqlx::query(
                            "UPDATE edges SET metadata = metadata || '{\"ab_status\": \"retired\"}' WHERE id = $1",
                        )
                        .bind(eid)
                        .execute(db)
                        .await;
                    }

                    tracing::info!(
                        article_id = %group.article_id,
                        edge_type = %group.edge_type,
                        winner = %best_id,
                        variants = ranked.len(),
                        p_value = p_value,
                        "A/B-test avgjort (multi-variant): vinner markert"
                    );

                    resolved += 1;
                }
            }
        }
    }

    Ok(resolved)
}

/// Start periodisk A/B-evaluering.
/// Kjører hvert 5. minutt, evaluerer aktive tester og markerer vinnere.
pub fn start_ab_evaluator(db: PgPool) {
    tokio::spawn(async move {
        // Vent 60 sekunder etter oppstart
        tokio::time::sleep(std::time::Duration::from_secs(60)).await;
        tracing::info!("A/B-evaluator startet (intervall: 300s)");

        loop {
            match evaluate_ab_tests(&db).await {
                Ok(count) => {
                    if count > 0 {
                        tracing::info!(resolved = count, "A/B-evaluator: {} tester avgjort", count);
                    }
                }
                Err(e) => {
                    tracing::error!(error = %e, "A/B-evaluator feilet");
                }
            }

            tokio::time::sleep(std::time::Duration::from_secs(300)).await;
        }
    });
}

/// POST /intentions/ab_override — redaktør overstyrer A/B-test.
///
/// Markerer valgt variant som "winner" og alle andre som "retired".
/// Krever owner/admin-tilgang til samlingen.
#[derive(Deserialize)]
pub struct AbOverrideRequest {
    pub edge_id: Uuid,
    pub article_id: Uuid,
}

pub async fn ab_override(
    State(state): State<AppState>,
    user: crate::auth::AuthUser,
    axum::Json(req): axum::Json<AbOverrideRequest>,
) -> Result<axum::Json<serde_json::Value>, StatusCode> {
    // Finn artikkelen og dens samling
    let edge_row: Option<(String, Uuid)> = sqlx::query_as(
        r#"
        SELECT e.edge_type, e.target_id
        FROM edges e
        WHERE e.id = $1
        "#,
    )
    .bind(req.edge_id)
    .fetch_optional(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    let Some((edge_type, article_id)) = edge_row else {
        return Err(StatusCode::NOT_FOUND);
    };

    if article_id != req.article_id {
        return Err(StatusCode::BAD_REQUEST);
    }

    // Sjekk at brukeren har tilgang (owner/admin av en samling artikkelen tilhører)
    let has_access: bool = sqlx::query_scalar(
        r#"
        SELECT EXISTS(
            SELECT 1
            FROM edges e_belongs
            JOIN edges e_role ON e_role.source_id = $2 AND e_role.target_id = e_belongs.target_id
                AND e_role.edge_type IN ('owner', 'admin')
            WHERE e_belongs.source_id = $1 AND e_belongs.edge_type = 'belongs_to'
        )
        "#,
    )
    .bind(article_id)
    .bind(user.node_id)
    .fetch_one(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    if !has_access {
        return Err(StatusCode::FORBIDDEN);
    }

    // Marker valgt variant som winner
    sqlx::query(
        "UPDATE edges SET metadata = metadata || '{\"ab_status\": \"winner\"}' WHERE id = $1",
    )
    .bind(req.edge_id)
    .execute(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    // Retire alle andre varianter av samme type til samme artikkel
    sqlx::query(
        r#"
        UPDATE edges
        SET metadata = metadata || '{"ab_status": "retired"}'
        WHERE target_id = $1
          AND edge_type = $2
          AND id != $3
          AND (metadata->>'ab_status' IS NULL OR metadata->>'ab_status' = 'testing')
        "#,
    )
    .bind(article_id)
    .bind(&edge_type)
    .bind(req.edge_id)
    .execute(&state.db)
    .await
    .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;

    tracing::info!(
        edge_id = %req.edge_id,
        article_id = %article_id,
        edge_type = %edge_type,
        user = %user.node_id,
        "A/B-test overstyrt av redaktør"
    );

    Ok(axum::Json(serde_json::json!({
        "status": "ok",
        "winner_edge_id": req.edge_id,
        "edge_type": edge_type
    })))
}

// =============================================================================
// A/B initialisering: sett testing-status på nye varianter automatisk
// =============================================================================

/// Sett ab_status = "testing" og started_at på en presentasjonselement-edge
/// når det finnes >1 variant av samme type til samme artikkel.
pub async fn maybe_start_ab_test(db: &PgPool, article_id: Uuid, edge_type: &str) {
    // Tell antall varianter (ikke-retired)
    let count: Option<(i64,)> = sqlx::query_as(
        r#"
        SELECT COUNT(*) FROM edges
        WHERE target_id = $1
          AND edge_type = $2
          AND (metadata->>'ab_status' IS NULL OR metadata->>'ab_status' != 'retired')
        "#,
    )
    .bind(article_id)
    .bind(edge_type)
    .fetch_optional(db)
    .await
    .unwrap_or(None);

    let count = count.map(|(c,)| c).unwrap_or(0);

    if count > 1 {
        // Marker alle varianter uten ab_status som "testing"
        let now = Utc::now().to_rfc3339();
        let _ = sqlx::query(
            r#"
            UPDATE edges
            SET metadata = metadata
                || jsonb_build_object('ab_status', 'testing', 'started_at', $3::text)
            WHERE target_id = $1
              AND edge_type = $2
              AND metadata->>'ab_status' IS NULL
            "#,
        )
        .bind(article_id)
        .bind(edge_type)
        .bind(&now)
        .execute(db)
        .await;

        tracing::info!(
            article_id = %article_id,
            edge_type = %edge_type,
            variants = count,
            "A/B-test startet automatisk"
        );
    }
}

// =============================================================================
// Tester
// =============================================================================

#[cfg(test)]
mod tests {
    use super::*;

    fn default_seo() -> SeoData {
        SeoData {
            og_title: "Test".to_string(),
            description: "Beskrivelse".to_string(),
            canonical_url: "https://example.com/test".to_string(),
            og_image: None,
            json_ld: "{}".to_string(),
        }
    }

    #[test]
    fn css_variables_use_defaults() {
        let config = ThemeConfig::default();
        let css = build_css_variables("avis", &config);
        assert!(css.contains("--color-primary: #1a1a2e"));
        assert!(css.contains("--font-heading: 'Georgia'"));
        assert!(css.contains("--layout-max-width: 1200px"));
    }

    #[test]
    fn css_variables_override() {
        let config = ThemeConfig {
            colors: ColorConfig {
                primary: Some("#ff0000".to_string()),
                ..Default::default()
            },
            ..Default::default()
        };
        let css = build_css_variables("blogg", &config);
        assert!(css.contains("--color-primary: #ff0000"));
        // Andre verdier skal fortsatt bruke blogg-defaults
        assert!(css.contains("--color-accent: #3498db"));
    }

    #[test]
    fn tera_builds_successfully() {
        let tera = build_tera();
        // Alle 8 tema-templates + base skal finnes
        let templates: Vec<&str> = tera.get_template_names().collect();
        assert!(templates.contains(&"base.html"));
        assert!(templates.contains(&"avis/article.html"));
        assert!(templates.contains(&"avis/index.html"));
        assert!(templates.contains(&"magasin/article.html"));
        assert!(templates.contains(&"magasin/index.html"));
        assert!(templates.contains(&"blogg/article.html"));
        assert!(templates.contains(&"blogg/index.html"));
        assert!(templates.contains(&"tidsskrift/article.html"));
        assert!(templates.contains(&"tidsskrift/index.html"));
    }

    #[test]
    fn render_article_all_themes() {
        let tera = build_tera();
        let config = ThemeConfig::default();
        let article = ArticleData {
            id: "test-id".to_string(),
            short_id: "test-sho".to_string(),
            title: "Testittel".to_string(),
            content: "<p>Testinnhold</p>".to_string(),
            subtitle: None,
            summary: Some("Kort oppsummering".to_string()),
            og_image: None,
            published_at: "2026-03-18T12:00:00Z".to_string(),
            published_at_short: "18. mars 2026".to_string(),
        };

        let seo = default_seo();

        for theme in &["avis", "magasin", "blogg", "tidsskrift"] {
            let html = render_article(&tera, theme, &config, &article, "Testsamling", "/pub/test", &seo, false)
                .unwrap_or_else(|e| panic!("Render feilet for {theme}: {e}"));
            assert!(html.contains("Testittel"), "Tittel mangler i {theme}");
            assert!(html.contains("Testinnhold"), "Innhold mangler i {theme}");
            assert!(html.contains("--color-primary"), "CSS-variabler mangler i {theme}");
        }
    }

    #[test]
    fn render_article_includes_seo() {
        let tera = build_tera();
        let config = ThemeConfig::default();
        let article = ArticleData {
            id: "seo-test".to_string(),
            short_id: "seo-test".to_string(),
            title: "SEO-tittel".to_string(),
            content: "<p>Innhold</p>".to_string(),
            subtitle: None,
            summary: Some("SEO-beskrivelse her".to_string()),
            og_image: None,
            published_at: "2026-03-18T12:00:00Z".to_string(),
            published_at_short: "18. mars 2026".to_string(),
        };

        let seo = SeoData {
            og_title: "SEO-tittel".to_string(),
            description: "SEO-beskrivelse her".to_string(),
            canonical_url: "https://example.com/seo-test".to_string(),
            og_image: None,
            json_ld: r#"{"@type":"Article"}"#.to_string(),
        };

        let html = render_article(&tera, "blogg", &config, &article, "Testpub", "/pub/test", &seo, false)
            .expect("Render feilet");

        assert!(html.contains("og:title"), "OG-tittel mangler");
        assert!(html.contains("og:description"), "OG-beskrivelse mangler");
        assert!(html.contains("canonical"), "Canonical URL mangler");
        assert!(html.contains("application/ld+json"), "JSON-LD mangler");
        assert!(html.contains("SEO-beskrivelse her"), "Beskrivelse mangler");
    }

    #[test]
    fn render_index_all_themes() {
        let tera = build_tera();
        let config = ThemeConfig::default();
        let index = IndexData {
            title: "Testforside".to_string(),
            description: None,
            hero: None,
            featured: vec![],
            stream: vec![ArticleData {
                id: "s1".to_string(),
                short_id: "s1000000".to_string(),
                title: "Strøm-artikkel".to_string(),
                subtitle: None,
                content: "Innhold".to_string(),
                summary: Some("Sammendrag".to_string()),
                og_image: None,
                published_at: "2026-03-18T12:00:00Z".to_string(),
                published_at_short: "18. mars 2026".to_string(),
            }],
        };

        for theme in &["avis", "magasin", "blogg", "tidsskrift"] {
            let html = render_index(&tera, theme, &config, &index, "/pub/test", false)
                .unwrap_or_else(|e| panic!("Render feilet for {theme}: {e}"));
            assert!(html.contains("Testforside"), "Tittel mangler i {theme}");
            assert!(html.contains("Strøm-artikkel"), "Strøm-artikkel mangler i {theme}");
        }
    }

    #[test]
    fn unknown_theme_falls_back_to_blogg() {
        let config = ThemeConfig::default();
        let css = build_css_variables("nonexistent", &config);
        let css_blogg = build_css_variables("blogg", &config);
        assert_eq!(css, css_blogg);
    }

    #[test]
    fn truncate_handles_multibyte_utf8() {
        // Norsk tekst med æ, ø, å skal ikke panikke
        let text = "Blåbærsyltetøy er en norsk spesialitet som smaker godt";
        let result = truncate(text, 15);
        assert!(result.ends_with('…') || result.len() <= 15 * 4);
        // Sjekk at resultatet er gyldig UTF-8 (implisitt ved å bruke String)
        assert!(!result.is_empty());

        // Emoji / 4-byte chars
        let emoji_text = "🎵🎶🎸🎹🎺🎻🎷 Musikk er flott";
        let result2 = truncate(emoji_text, 5);
        assert!(!result2.is_empty());
    }

    #[test]
    fn truncate_short_string_unchanged() {
        let text = "Kort tekst";
        assert_eq!(truncate(text, 20), "Kort tekst");
    }

    #[test]
    fn json_ld_escapes_script_tags() {
        let article = ArticleData {
            id: "xss".to_string(),
            short_id: "xss12345".to_string(),
            title: "Test</script><script>alert(1)".to_string(),
            subtitle: None,
            content: "Safe".to_string(),
            summary: Some("Safe summary".to_string()),
            og_image: None,
            published_at: "2026-03-18T12:00:00Z".to_string(),
            published_at_short: "18. mars 2026".to_string(),
        };
        let ld = build_json_ld(&article, "Pub", "https://example.com/xss");
        // Skal ikke inneholde rå </script>
        assert!(!ld.contains("</script>"), "JSON-LD inneholder uescaped </script>: {ld}");
        assert!(ld.contains("<\\/script>"), "JSON-LD mangler escaped </script>: {ld}");
    }

    #[test]
    fn z_test_insufficient_data_returns_1() {
        // For lite data: returnerer p=1.0 (ingen signifikans)
        assert_eq!(z_test_proportions(10, 5, 10, 3), 1.0);
    }

    #[test]
    fn z_test_significant_difference() {
        // Variant A: 1000 imp, 100 klikk (10% CTR)
        // Variant B: 1000 imp, 50 klikk (5% CTR)
        let p = z_test_proportions(1000, 100, 1000, 50);
        assert!(p < 0.05, "Forventet signifikant forskjell, fikk p={p}");
    }

    #[test]
    fn z_test_no_significant_difference() {
        // Variant A: 100 imp, 10 klikk (10% CTR)
        // Variant B: 100 imp, 9 klikk (9% CTR)
        let p = z_test_proportions(100, 10, 100, 9);
        assert!(p > 0.05, "Forventet ingen signifikant forskjell, fikk p={p}");
    }

    #[test]
    fn json_ld_contains_required_fields() {
        let article = ArticleData {
            id: "test".to_string(),
            short_id: "test1234".to_string(),
            title: "Test-artikkel".to_string(),
            subtitle: None,
            content: "Innhold".to_string(),
            summary: Some("Oppsummering".to_string()),
            og_image: None,
            published_at: "2026-03-18T12:00:00Z".to_string(),
            published_at_short: "18. mars 2026".to_string(),
        };

        let ld = build_json_ld(&article, "Testpub", "https://example.com/test");
        assert!(ld.contains("\"@type\":\"Article\""));
        assert!(ld.contains("\"headline\":\"Test-artikkel\""));
        assert!(ld.contains("\"datePublished\""));
        assert!(ld.contains("\"publisher\""));
    }
}