// synops-calendar — Importer ICS-filer til kalendernoder i Synops.
//
// Parser en ICS-fil (RFC 5545) og oppretter content-noder med
// scheduled-edges for hver VEVENT. Duplikatdeteksjon via ICS UID:
// ved re-import oppdateres eksisterende noder.
//
// Bruk:
//   synops-calendar --file kalender.ics --collection-id <uuid>
//   synops-calendar --url https://calendar.google.com/...ical --collection-id <uuid>
//   synops-calendar --payload-json '{"url":"...","collection_id":"..."}'
//
// Output: JSON til stdout med antall opprettet/oppdatert/feilet.
// Feil: stderr + exit code != 0.
//
// Ref: docs/retninger/unix_filosofi.md, docs/primitiver/edges.md

use chrono::{DateTime, NaiveDate, NaiveDateTime, Utc};
use clap::Parser;
use ical::parser::ical::component::IcalEvent;
use serde::{Deserialize, Serialize};
use sqlx::PgPool;
use std::io::BufReader;
use uuid::Uuid;

/// Importer ICS-fil til kalendernoder.
#[derive(Parser)]
#[command(name = "synops-calendar", about = "Importer ICS-fil eller CalDAV-URL til kalendernoder i Synops")]
struct Cli {
    /// Sti til ICS-fil
    #[arg(long)]
    file: Option<String>,

    /// URL til ICS/CalDAV-kalender (hentes via HTTP GET)
    #[arg(long)]
    url: Option<String>,

    /// Samlings-ID (node som hendelsene tilhører)
    #[arg(long)]
    collection_id: Option<Uuid>,

    /// Payload fra jobbkø (JSON). Overstyrer andre argumenter.
    #[arg(long)]
    payload_json: Option<String>,
}

#[derive(Deserialize)]
struct JobPayload {
    #[serde(default)]
    file: Option<String>,
    #[serde(default)]
    url: Option<String>,
    collection_id: String,
}

/// Parsed calendar event fra ICS.
struct CalendarEvent {
    uid: String,
    summary: Option<String>,
    description: Option<String>,
    dtstart: Option<String>,
    dtend: Option<String>,
    location: Option<String>,
}

#[derive(Serialize)]
struct ImportResult {
    ok: bool,
    created: usize,
    updated: usize,
    errors: Vec<String>,
}

/// Kilde for ICS-data.
enum IcsSource {
    File(String),
    Url(String),
}

#[tokio::main]
async fn main() {
    synops_common::logging::init("synops_calendar");

    let cli = Cli::parse();

    let (source, collection_id) = if let Some(ref json_str) = cli.payload_json {
        let payload: JobPayload = serde_json::from_str(json_str).unwrap_or_else(|e| {
            eprintln!("Ugyldig --payload-json: {e}");
            std::process::exit(1);
        });
        let cid = payload.collection_id.parse::<Uuid>().unwrap_or_else(|e| {
            eprintln!("Ugyldig collection_id i payload: {e}");
            std::process::exit(1);
        });
        let source = if let Some(url) = payload.url {
            IcsSource::Url(url)
        } else if let Some(file) = payload.file {
            IcsSource::File(file)
        } else {
            eprintln!("Payload må inneholde 'url' eller 'file'");
            std::process::exit(1);
        };
        (source, cid)
    } else if let Some(url) = cli.url {
        let cid = cli.collection_id.unwrap_or_else(|| {
            eprintln!("Mangler --collection-id");
            std::process::exit(1);
        });
        (IcsSource::Url(url), cid)
    } else {
        let file = cli.file.unwrap_or_else(|| {
            eprintln!("Mangler --file eller --url");
            std::process::exit(1);
        });
        let cid = cli.collection_id.unwrap_or_else(|| {
            eprintln!("Mangler --collection-id");
            std::process::exit(1);
        });
        (IcsSource::File(file), cid)
    };

    // Hent ICS-data
    let ics_data = match &source {
        IcsSource::File(path) => {
            std::fs::read_to_string(path).unwrap_or_else(|e| {
                eprintln!("Kunne ikke lese {path}: {e}");
                std::process::exit(1);
            })
        }
        IcsSource::Url(url) => {
            tracing::info!(url = %url, "Henter ICS fra URL");
            fetch_ics(url).await.unwrap_or_else(|e| {
                eprintln!("Kunne ikke hente {url}: {e}");
                std::process::exit(1);
            })
        }
    };

    // Parse ICS-data
    let events = parse_ics_data(&ics_data);

    if events.is_empty() {
        let output = ImportResult {
            ok: true,
            created: 0,
            updated: 0,
            errors: vec!["Ingen VEVENT funnet i ICS-data".to_string()],
        };
        println!("{}", serde_json::to_string_pretty(&output).unwrap());
        return;
    }

    let source_label = match &source {
        IcsSource::File(path) => path.clone(),
        IcsSource::Url(url) => url.clone(),
    };
    tracing::info!(events = events.len(), source = %source_label, "Parsed ICS-data");

    // Koble til database
    let db = synops_common::db::connect().await.unwrap_or_else(|e| {
        eprintln!("{e}");
        std::process::exit(1);
    });

    // Verifiser at collection-noden eksisterer
    let collection_exists: bool = sqlx::query_scalar(
        "SELECT EXISTS(SELECT 1 FROM nodes WHERE id = $1)",
    )
    .bind(collection_id)
    .fetch_one(&db)
    .await
    .unwrap_or_else(|e| {
        eprintln!("DB-feil ved oppslag av samling: {e}");
        std::process::exit(1);
    });

    if !collection_exists {
        eprintln!("Samlings-node {collection_id} finnes ikke");
        std::process::exit(1);
    }

    // Importer hendelser
    let mut created = 0usize;
    let mut updated = 0usize;
    let mut errors = Vec::new();

    for event in &events {
        match import_event(&db, event, collection_id).await {
            Ok(EventAction::Created) => created += 1,
            Ok(EventAction::Updated) => updated += 1,
            Err(e) => {
                let uid = &event.uid;
                let msg = format!("Feil ved import av {uid}: {e}");
                tracing::warn!("{}", msg);
                errors.push(msg);
            }
        }
    }

    let all_ok = errors.is_empty();
    let output = ImportResult {
        ok: all_ok,
        created,
        updated,
        errors,
    };

    tracing::info!(created, updated, errors = output.errors.len(), "Import fullført");
    println!("{}", serde_json::to_string_pretty(&output).unwrap());

    if !all_ok {
        std::process::exit(1);
    }
}

/// Hent ICS-data fra en URL via HTTP GET.
async fn fetch_ics(url: &str) -> Result<String, String> {
    let client = reqwest::Client::builder()
        .timeout(std::time::Duration::from_secs(30))
        .build()
        .map_err(|e| format!("Kunne ikke opprette HTTP-klient: {e}"))?;

    let response = client
        .get(url)
        .header("User-Agent", "synops-calendar/0.1")
        .send()
        .await
        .map_err(|e| format!("HTTP-forespørsel feilet: {e}"))?;

    if !response.status().is_success() {
        return Err(format!("HTTP {}: {}", response.status(), url));
    }

    let body = response
        .text()
        .await
        .map_err(|e| format!("Kunne ikke lese respons: {e}"))?;

    // Enkel validering: sjekk at det ser ut som ICS
    if !body.contains("BEGIN:VCALENDAR") {
        return Err(format!("Responsen ser ikke ut som ICS-data (mangler BEGIN:VCALENDAR)"));
    }

    Ok(body)
}

enum EventAction {
    Created,
    Updated,
}

/// Importer én kalender-hendelse. Duplikatdeteksjon via UID i metadata.
async fn import_event(
    db: &PgPool,
    event: &CalendarEvent,
    collection_id: Uuid,
) -> Result<EventAction, String> {
    let dtstart = event.dtstart.as_deref().ok_or("Mangler DTSTART")?;
    let at = parse_ics_datetime(dtstart).ok_or_else(|| format!("Kunne ikke parse DTSTART: {dtstart}"))?;
    let at_str = at.to_rfc3339();

    let title = event.summary.clone().unwrap_or_default();

    // Bygg metadata
    let mut meta = serde_json::json!({
        "ics_uid": event.uid,
    });
    if let Some(ref loc) = event.location {
        meta["location"] = serde_json::Value::String(loc.clone());
    }
    if let Some(ref dtend) = event.dtend {
        if let Some(end) = parse_ics_datetime(dtend) {
            meta["dtend"] = serde_json::Value::String(end.to_rfc3339());
        }
    }

    // Sjekk om noden allerede eksisterer (duplikatdeteksjon via ics_uid)
    let existing: Option<Uuid> = sqlx::query_scalar(
        r#"SELECT n.id FROM nodes n
           JOIN edges e ON e.source_id = n.id
           WHERE e.target_id = $1
             AND e.edge_type = 'belongs_to'
             AND n.metadata->>'ics_uid' = $2"#,
    )
    .bind(collection_id)
    .bind(&event.uid)
    .fetch_optional(db)
    .await
    .map_err(|e| format!("DB-feil ved duplikatsjekk: {e}"))?;

    if let Some(node_id) = existing {
        // Oppdater eksisterende node
        let mut tx = db.begin().await.map_err(|e| format!("Transaksjon feilet: {e}"))?;

        sqlx::query(
            "UPDATE nodes SET title = $1, content = $2, metadata = $3 WHERE id = $4",
        )
        .bind(&title)
        .bind(event.description.as_deref())
        .bind(&meta)
        .bind(node_id)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke oppdatere node: {e}"))?;

        // Oppdater scheduled-edge metadata
        let sched_meta = serde_json::json!({ "at": at_str });
        sqlx::query(
            r#"UPDATE edges SET metadata = $1
               WHERE source_id = $2 AND target_id = $3 AND edge_type = 'scheduled'"#,
        )
        .bind(&sched_meta)
        .bind(node_id)
        .bind(collection_id)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke oppdatere scheduled-edge: {e}"))?;

        tx.commit().await.map_err(|e| format!("Commit feilet: {e}"))?;

        tracing::debug!(node_id = %node_id, uid = %event.uid, "Oppdatert eksisterende hendelse");
        Ok(EventAction::Updated)
    } else {
        // Opprett ny node + edges
        let node_id = Uuid::now_v7();
        let mut tx = db.begin().await.map_err(|e| format!("Transaksjon feilet: {e}"))?;

        sqlx::query(
            r#"INSERT INTO nodes (id, node_kind, title, content, visibility, metadata)
               VALUES ($1, 'content', $2, $3, 'hidden', $4)"#,
        )
        .bind(node_id)
        .bind(&title)
        .bind(event.description.as_deref())
        .bind(&meta)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke opprette node: {e}"))?;

        // belongs_to-edge: hendelse → samling
        sqlx::query(
            r#"INSERT INTO edges (id, source_id, target_id, edge_type, metadata)
               VALUES ($1, $2, $3, 'belongs_to', '{}')"#,
        )
        .bind(Uuid::now_v7())
        .bind(node_id)
        .bind(collection_id)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke opprette belongs_to-edge: {e}"))?;

        // scheduled-edge: hendelse → samling med tidspunkt
        let sched_meta = serde_json::json!({ "at": at_str });
        sqlx::query(
            r#"INSERT INTO edges (id, source_id, target_id, edge_type, metadata)
               VALUES ($1, $2, $3, 'scheduled', $4)"#,
        )
        .bind(Uuid::now_v7())
        .bind(node_id)
        .bind(collection_id)
        .bind(&sched_meta)
        .execute(&mut *tx)
        .await
        .map_err(|e| format!("Kunne ikke opprette scheduled-edge: {e}"))?;

        tx.commit().await.map_err(|e| format!("Commit feilet: {e}"))?;

        tracing::debug!(node_id = %node_id, uid = %event.uid, "Opprettet ny hendelse");
        Ok(EventAction::Created)
    }
}

/// Parse ICS-data fra en streng og returner liste med hendelser.
fn parse_ics_data(data: &str) -> Vec<CalendarEvent> {
    let reader = BufReader::new(data.as_bytes());
    let parser = ical::IcalParser::new(reader);

    let mut events = Vec::new();

    for calendar in parser {
        let calendar = match calendar {
            Ok(c) => c,
            Err(e) => {
                eprintln!("Feil ved parsing av ICS: {e}");
                continue;
            }
        };

        for vevent in calendar.events {
            if let Some(event) = extract_event(&vevent) {
                events.push(event);
            }
        }
    }

    events
}

/// Ekstraher relevant data fra en VEVENT.
fn extract_event(vevent: &IcalEvent) -> Option<CalendarEvent> {
    let uid = get_property(vevent, "UID")?;

    Some(CalendarEvent {
        uid,
        summary: get_property(vevent, "SUMMARY"),
        description: get_property(vevent, "DESCRIPTION"),
        dtstart: get_property(vevent, "DTSTART"),
        dtend: get_property(vevent, "DTEND"),
        location: get_property(vevent, "LOCATION"),
    })
}

/// Hent en property-verdi fra en VEVENT.
fn get_property(vevent: &IcalEvent, name: &str) -> Option<String> {
    vevent
        .properties
        .iter()
        .find(|p| p.name == name)
        .and_then(|p| p.value.clone())
}

/// Parse ICS datetime-streng til UTC DateTime.
///
/// Støtter formater:
///   - 20260320T140000Z (UTC)
///   - 20260320T140000 (lokal, tolkes som UTC)
///   - 20260320 (heldagshendelse)
fn parse_ics_datetime(s: &str) -> Option<DateTime<Utc>> {
    let s = s.trim();

    // Fjern TZID-prefix om det finnes (noen ICS-filer har dette i verdien)
    let s = if s.contains(':') {
        s.rsplit(':').next().unwrap_or(s)
    } else {
        s
    };

    // 20260320T140000Z
    if s.ends_with('Z') {
        let s = &s[..s.len() - 1];
        let naive = NaiveDateTime::parse_from_str(s, "%Y%m%dT%H%M%S").ok()?;
        return Some(naive.and_utc());
    }

    // 20260320T140000
    if s.contains('T') {
        let naive = NaiveDateTime::parse_from_str(s, "%Y%m%dT%H%M%S").ok()?;
        return Some(naive.and_utc());
    }

    // 20260320 (heldagshendelse → 00:00 UTC)
    let date = NaiveDate::parse_from_str(s, "%Y%m%d").ok()?;
    Some(
        date.and_hms_opt(0, 0, 0)?
            .and_utc(),
    )
}