// Tunge spørringer — lesestien via PostgreSQL med RLS.
//
// For søk, statistikk, og graf-traversering brukes PG direkte (ikke STDB).
// Alle spørringer kjøres med SET LOCAL ROLE synops_reader, som er underlagt
// RLS-policies. Brukerens node_id settes som sesjonsvariabel.
//
// Ref: docs/retninger/datalaget.md (tunge spørringer-seksjonen)

use axum::{extract::State, http::StatusCode, Json};
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use uuid::Uuid;

use crate::auth::AuthUser;
use crate::AppState;
use crate::intentions::ErrorResponse;

// =============================================================================
// GET /query/segments — transkripsjons-segmenter for en node
// =============================================================================

#[derive(Deserialize)]
pub struct QuerySegmentsRequest {
    /// Node-ID for media-noden.
    pub node_id: Uuid,
}

#[derive(Serialize, sqlx::FromRow)]
pub struct SegmentResult {
    pub id: i64,
    pub seq: i32,
    pub start_ms: i32,
    pub end_ms: i32,
    pub content: String,
    pub edited: bool,
}

#[derive(Serialize)]
pub struct QuerySegmentsResponse {
    pub segments: Vec<SegmentResult>,
    pub transcribed_at: Option<String>,
}

/// GET /query/segments?node_id=...
///
/// Henter nyeste transkripsjons-segmenter for en media-node.
/// Verifiserer tilgang via RLS på nodes-tabellen først.
pub async fn query_segments(
    State(state): State<AppState>,
    user: AuthUser,
    axum::extract::Query(params): axum::extract::Query<QuerySegmentsRequest>,
) -> Result<Json<QuerySegmentsResponse>, (StatusCode, Json<ErrorResponse>)> {
    let result = run_query_segments(&state.db, user.node_id, params.node_id).await;
    match result {
        Ok(resp) => Ok(Json(resp)),
        Err(e) => {
            tracing::error!(error = %e, "query_segments feilet");
            Err(internal_error("Databasefeil ved henting av segmenter"))
        }
    }
}

async fn run_query_segments(
    db: &PgPool,
    user_node_id: Uuid,
    node_id: Uuid,
) -> Result<QuerySegmentsResponse, sqlx::Error> {
    // Verifiser tilgang: sjekk at brukeren kan se noden via RLS
    let mut tx = db.begin().await?;
    set_rls_context(&mut tx, user_node_id).await?;

    let exists = sqlx::query_scalar::<_, bool>(
        "SELECT EXISTS(SELECT 1 FROM nodes WHERE id = $1)",
    )
    .bind(node_id)
    .fetch_one(&mut *tx)
    .await?;

    tx.commit().await?;

    if !exists {
        return Ok(QuerySegmentsResponse {
            segments: vec![],
            transcribed_at: None,
        });
    }

    // Hent nyeste transcribed_at for denne noden
    let latest: Option<(chrono::DateTime<chrono::Utc>,)> = sqlx::query_as(
        "SELECT transcribed_at FROM transcription_segments WHERE node_id = $1 ORDER BY transcribed_at DESC LIMIT 1",
    )
    .bind(node_id)
    .fetch_optional(db)
    .await?;

    let Some((transcribed_at,)) = latest else {
        return Ok(QuerySegmentsResponse {
            segments: vec![],
            transcribed_at: None,
        });
    };

    // Hent alle segmenter for nyeste kjøring
    let segments = sqlx::query_as::<_, SegmentResult>(
        r#"
        SELECT id, seq, start_ms, end_ms, content, edited
        FROM transcription_segments
        WHERE node_id = $1 AND transcribed_at = $2
        ORDER BY seq
        "#,
    )
    .bind(node_id)
    .bind(transcribed_at)
    .fetch_all(db)
    .await?;

    Ok(QuerySegmentsResponse {
        segments,
        transcribed_at: Some(transcribed_at.to_rfc3339()),
    })
}

// =============================================================================
// RLS-kontekst
// =============================================================================

/// Setter opp RLS-kontekst for en transaksjon.
/// Etter dette kallet er alle SELECT-spørringer filtrert via node_access.
///
/// MÅ kalles innenfor en transaksjon (SET LOCAL gjelder kun innenfor tx).
async fn set_rls_context(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    user_node_id: Uuid,
) -> Result<(), sqlx::Error> {
    // Sett brukerens node_id som sesjonsvariabel
    sqlx::query(&format!(
        "SET LOCAL app.current_node_id = '{}'",
        user_node_id
    ))
    .execute(&mut **tx)
    .await?;

    // Bytt til synops_reader-rollen (underlagt RLS)
    sqlx::query("SET LOCAL ROLE synops_reader")
        .execute(&mut **tx)
        .await?;

    Ok(())
}

// =============================================================================
// GET /query/nodes — søk og filtrering av noder
// =============================================================================

#[derive(Deserialize)]
pub struct QueryNodesRequest {
    /// Fritekst-søk i tittel og innhold. Valgfritt.
    pub q: Option<String>,
    /// Filtrer på node_kind. Valgfritt.
    pub kind: Option<String>,
    /// Maks antall resultater. Default: 50.
    pub limit: Option<i64>,
    /// Offset for paginering. Default: 0.
    pub offset: Option<i64>,
}

#[derive(Serialize, sqlx::FromRow)]
pub struct QueryNodeResult {
    pub id: Uuid,
    pub node_kind: String,
    pub title: Option<String>,
    pub content: Option<String>,
    pub visibility: String,
    pub metadata: serde_json::Value,
    pub created_at: chrono::DateTime<chrono::Utc>,
    pub created_by: Option<Uuid>,
}

#[derive(Serialize)]
pub struct QueryNodesResponse {
    pub nodes: Vec<QueryNodeResult>,
    pub total: i64,
}

fn internal_error(msg: &str) -> (StatusCode, Json<ErrorResponse>) {
    (
        StatusCode::INTERNAL_SERVER_ERROR,
        Json(ErrorResponse {
            error: msg.to_string(),
        }),
    )
}

/// GET /query/nodes?q=...&kind=...&limit=...&offset=...
///
/// Søk og filtrering av noder. Bruker RLS — returnerer kun noder
/// brukeren har tilgang til.
pub async fn query_nodes(
    State(state): State<AppState>,
    user: AuthUser,
    axum::extract::Query(params): axum::extract::Query<QueryNodesRequest>,
) -> Result<Json<QueryNodesResponse>, (StatusCode, Json<ErrorResponse>)> {
    let limit = params.limit.unwrap_or(50).min(200);
    let offset = params.offset.unwrap_or(0).max(0);

    let result = run_query_nodes(&state.db, user.node_id, &params.q, &params.kind, limit, offset).await;

    match result {
        Ok(resp) => Ok(Json(resp)),
        Err(e) => {
            tracing::error!(error = %e, "query_nodes feilet");
            Err(internal_error("Databasefeil ved søk"))
        }
    }
}

async fn run_query_nodes(
    db: &PgPool,
    user_node_id: Uuid,
    q: &Option<String>,
    kind: &Option<String>,
    limit: i64,
    offset: i64,
) -> Result<QueryNodesResponse, sqlx::Error> {
    let mut tx = db.begin().await?;
    set_rls_context(&mut tx, user_node_id).await?;

    // Bygg spørring basert på filtre
    let (nodes, total) = if let Some(search) = q.as_deref().filter(|s| !s.is_empty()) {
        let search_pattern = format!("%{}%", search.replace('%', "\\%").replace('_', "\\_"));

        let nodes = sqlx::query_as::<_, QueryNodeResult>(
            r#"
            SELECT id, node_kind, title, content, visibility::text as visibility,
                   metadata, created_at, created_by
            FROM nodes
            WHERE (title ILIKE $1 OR content ILIKE $1)
            ORDER BY created_at DESC
            LIMIT $2 OFFSET $3
            "#,
        )
        .bind(&search_pattern)
        .bind(limit)
        .bind(offset)
        .fetch_all(&mut *tx)
        .await?;

        let total: (i64,) = sqlx::query_as(
            "SELECT COUNT(*) FROM nodes WHERE (title ILIKE $1 OR content ILIKE $1)",
        )
        .bind(&search_pattern)
        .fetch_one(&mut *tx)
        .await?;

        (nodes, total.0)
    } else if let Some(kind) = kind.as_deref().filter(|s| !s.is_empty()) {
        let nodes = sqlx::query_as::<_, QueryNodeResult>(
            r#"
            SELECT id, node_kind, title, content, visibility::text as visibility,
                   metadata, created_at, created_by
            FROM nodes
            WHERE node_kind = $1
            ORDER BY created_at DESC
            LIMIT $2 OFFSET $3
            "#,
        )
        .bind(kind)
        .bind(limit)
        .bind(offset)
        .fetch_all(&mut *tx)
        .await?;

        let total: (i64,) = sqlx::query_as(
            "SELECT COUNT(*) FROM nodes WHERE node_kind = $1",
        )
        .bind(kind)
        .fetch_one(&mut *tx)
        .await?;

        (nodes, total.0)
    } else {
        let nodes = sqlx::query_as::<_, QueryNodeResult>(
            r#"
            SELECT id, node_kind, title, content, visibility::text as visibility,
                   metadata, created_at, created_by
            FROM nodes
            ORDER BY created_at DESC
            LIMIT $1 OFFSET $2
            "#,
        )
        .bind(limit)
        .bind(offset)
        .fetch_all(&mut *tx)
        .await?;

        let total: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM nodes")
            .fetch_one(&mut *tx)
            .await?;

        (nodes, total.0)
    };

    // Transaksjon avsluttes — SET LOCAL tilbakestilles automatisk
    tx.commit().await?;

    Ok(QueryNodesResponse { nodes, total })
}