// Jobbkø — PostgreSQL-basert asynkron jobbehandling.
//
// Enkel polling-loop med SELECT ... FOR UPDATE SKIP LOCKED.
// Dispatching til handler-funksjoner basert på job_type.
//
// Ref: docs/infra/jobbkø.md

use sqlx::PgPool;
use uuid::Uuid;

use crate::agent;
use crate::ai_edges;
use crate::audio;
use crate::cas::CasStore;
use crate::maintenance::MaintenanceState;
use crate::publishing;
use crate::stdb::StdbClient;
use crate::summarize;
use crate::transcribe;
use crate::tts;

/// Rad fra job_queue-tabellen.
#[derive(sqlx::FromRow, Debug)]
pub struct JobRow {
    pub id: Uuid,
    pub collection_node_id: Option<Uuid>,
    pub job_type: String,
    pub payload: serde_json::Value,
    pub attempts: i16,
    pub max_attempts: i16,
}

/// Legger en ny jobb i køen.
pub async fn enqueue(
    db: &PgPool,
    job_type: &str,
    payload: serde_json::Value,
    collection_node_id: Option<Uuid>,
    priority: i16,
) -> Result<Uuid, sqlx::Error> {
    let row = sqlx::query_scalar::<_, Uuid>(
        r#"
        INSERT INTO job_queue (job_type, payload, collection_node_id, priority)
        VALUES ($1, $2, $3, $4)
        RETURNING id
        "#,
    )
    .bind(job_type)
    .bind(&payload)
    .bind(collection_node_id)
    .bind(priority)
    .fetch_one(db)
    .await?;

    tracing::info!(job_id = %row, job_type = %job_type, "Jobb lagt i kø");
    Ok(row)
}

/// Henter neste ventende jobb (atomisk med FOR UPDATE SKIP LOCKED).
/// Setter status til 'running' og oppdaterer started_at.
async fn dequeue(db: &PgPool) -> Result<Option<JobRow>, sqlx::Error> {
    let mut tx = db.begin().await?;

    let job = sqlx::query_as::<_, JobRow>(
        r#"
        SELECT id, collection_node_id, job_type, payload, attempts, max_attempts
        FROM job_queue
        WHERE status IN ('pending', 'retry')
          AND scheduled_for <= now()
        ORDER BY priority DESC, scheduled_for ASC
        LIMIT 1
        FOR UPDATE SKIP LOCKED
        "#,
    )
    .fetch_optional(&mut *tx)
    .await?;

    if let Some(ref job) = job {
        sqlx::query(
            "UPDATE job_queue SET status = 'running', started_at = now(), attempts = attempts + 1 WHERE id = $1",
        )
        .bind(job.id)
        .execute(&mut *tx)
        .await?;
    }

    tx.commit().await?;
    Ok(job)
}

/// Markerer en jobb som fullført.
async fn complete_job(db: &PgPool, job_id: Uuid, result: serde_json::Value) -> Result<(), sqlx::Error> {
    sqlx::query(
        "UPDATE job_queue SET status = 'completed', result = $2, completed_at = now() WHERE id = $1",
    )
    .bind(job_id)
    .bind(&result)
    .execute(db)
    .await?;
    Ok(())
}

/// Markerer en jobb som feilet. Settes til 'retry' med backoff hvis forsøk gjenstår,
/// ellers 'error'.
async fn fail_job(db: &PgPool, job: &JobRow, error_msg: &str) -> Result<(), sqlx::Error> {
    if job.attempts < job.max_attempts {
        // Eksponentiell backoff: 30s × 2^(attempts-1)
        let backoff_secs = 30i64 * 2i64.pow((job.attempts).max(0) as u32);
        sqlx::query(
            r#"
            UPDATE job_queue
            SET status = 'retry',
                error_msg = $2,
                scheduled_for = now() + ($3 || ' seconds')::interval
            WHERE id = $1
            "#,
        )
        .bind(job.id)
        .bind(error_msg)
        .bind(backoff_secs.to_string())
        .execute(db)
        .await?;

        tracing::warn!(
            job_id = %job.id,
            attempt = job.attempts,
            max = job.max_attempts,
            backoff_secs = backoff_secs,
            "Jobb feilet, retry planlagt"
        );
    } else {
        sqlx::query(
            "UPDATE job_queue SET status = 'error', error_msg = $2, completed_at = now() WHERE id = $1",
        )
        .bind(job.id)
        .bind(error_msg)
        .execute(db)
        .await?;

        tracing::error!(
            job_id = %job.id,
            attempts = job.attempts,
            "Jobb permanent feilet"
        );
    }
    Ok(())
}

/// Dispatcher — kjører riktig handler basert på job_type.
async fn dispatch(
    job: &JobRow,
    db: &PgPool,
    stdb: &StdbClient,
    cas: &CasStore,
    whisper_url: &str,
) -> Result<serde_json::Value, String> {
    match job.job_type.as_str() {
        "whisper_transcribe" => {
            transcribe::handle_whisper_job(job, db, stdb, cas, whisper_url).await
        }
        "agent_respond" => {
            agent::handle_agent_respond(job, db, stdb).await
        }
        "suggest_edges" => {
            ai_edges::handle_suggest_edges(job, db, stdb).await
        }
        "summarize_communication" => {
            summarize::handle_summarize_communication(job, db, stdb).await
        }
        "tts_generate" => {
            tts::handle_tts_job(job, db, stdb, cas).await
        }
        "audio_process" => {
            audio::handle_audio_process_job(job, db, stdb, cas).await
        }
        "render_article" => {
            handle_render_article(job, db, cas).await
        }
        "render_index" => {
            handle_render_index(job, db, cas).await
        }
        other => Err(format!("Ukjent jobbtype: {other}")),
    }
}

/// Handler for `render_article`-jobb.
///
/// Payload: `{ "node_id": "...", "collection_id": "..." }`
/// Rendrer artikkelens metadata.document til HTML via Tera, lagrer i CAS,
/// oppdaterer nodens metadata.rendered.
async fn handle_render_article(
    job: &JobRow,
    db: &PgPool,
    cas: &CasStore,
) -> Result<serde_json::Value, String> {
    let node_id: Uuid = job
        .payload
        .get("node_id")
        .and_then(|v| v.as_str())
        .and_then(|s| s.parse().ok())
        .ok_or("Mangler node_id i payload")?;

    let collection_id: Uuid = job
        .payload
        .get("collection_id")
        .and_then(|v| v.as_str())
        .and_then(|s| s.parse().ok())
        .ok_or("Mangler collection_id i payload")?;

    publishing::render_article_to_cas(db, cas, node_id, collection_id).await
}

/// Handler for `render_index`-jobb.
///
/// Payload: `{ "collection_id": "..." }`
/// Rendrer forsiden til HTML via Tera, lagrer i CAS,
/// oppdaterer samlingens metadata.rendered_index.
async fn handle_render_index(
    job: &JobRow,
    db: &PgPool,
    cas: &CasStore,
) -> Result<serde_json::Value, String> {
    let collection_id: Uuid = job
        .payload
        .get("collection_id")
        .and_then(|v| v.as_str())
        .and_then(|s| s.parse().ok())
        .ok_or("Mangler collection_id i payload")?;

    publishing::render_index_to_cas(db, cas, collection_id).await
}

/// Starter worker-loopen som poller job_queue.
/// Kjører som en bakgrunnsoppgave i tokio.
///
/// Respekterer vedlikeholdsmodus: når `maintenance.is_active()` er true,
/// slutter workeren å dequeue nye jobber (kjørende jobber fullføres).
pub fn start_worker(db: PgPool, stdb: StdbClient, cas: CasStore, maintenance: MaintenanceState) {
    let whisper_url = std::env::var("WHISPER_URL")
        .unwrap_or_else(|_| "http://faster-whisper:8000".to_string());

    tokio::spawn(async move {
        tracing::info!("Jobbkø-worker startet (poll-intervall: 2s)");

        loop {
            // Sjekk vedlikeholdsmodus — ikke dequeue nye jobber
            if maintenance.is_active() {
                tracing::debug!("Vedlikeholdsmodus aktiv — jobbkø pauset");
                tokio::time::sleep(std::time::Duration::from_secs(5)).await;
                continue;
            }

            match dequeue(&db).await {
                Ok(Some(job)) => {
                    tracing::info!(
                        job_id = %job.id,
                        job_type = %job.job_type,
                        attempt = job.attempts,
                        "Behandler jobb"
                    );

                    match dispatch(&job, &db, &stdb, &cas, &whisper_url).await {
                        Ok(result) => {
                            if let Err(e) = complete_job(&db, job.id, result).await {
                                tracing::error!(job_id = %job.id, error = %e, "Kunne ikke markere jobb som fullført");
                            } else {
                                tracing::info!(job_id = %job.id, "Jobb fullført");
                            }
                        }
                        Err(err) => {
                            tracing::error!(job_id = %job.id, error = %err, "Jobb feilet");
                            if let Err(e) = fail_job(&db, &job, &err).await {
                                tracing::error!(job_id = %job.id, error = %e, "Kunne ikke markere jobb som feilet");
                            }
                        }
                    }
                }
                Ok(None) => {
                    // Ingen ventende jobber — vent før neste poll
                    tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                }
                Err(e) => {
                    tracing::error!(error = %e, "Feil ved polling av jobbkø");
                    tokio::time::sleep(std::time::Duration::from_secs(5)).await;
                }
            }
        }
    });
}