// Jobbkø — PostgreSQL-basert asynkron jobbehandling.
//
// Enkel polling-loop med SELECT ... FOR UPDATE SKIP LOCKED.
// Dispatching til handler-funksjoner basert på job_type.
// Ressursstyring: semaphore for concurrency, prioritetsregler fra PG,
// LiveKit-bevisst resource governor (oppgave 15.5).
//
// Ref: docs/infra/jobbkø.md

use chrono::{DateTime, Utc};
use serde::Serialize;
use sqlx::PgPool;
use std::sync::Arc;
use tokio::sync::Semaphore;
use uuid::Uuid;

use crate::agent;
use crate::ai_edges;
use crate::ai_process;
use crate::audio;
use crate::cas::CasStore;
use crate::cli_dispatch;
use crate::maintenance::MaintenanceState;
use crate::pg_writes;
use crate::publishing::IndexCache;
use crate::resources::{self, PriorityRules};
use crate::summarize;
use crate::transcribe;
use crate::tts;

/// Maks total CPU-vekt som kan kjøre samtidig.
/// Standard: 8 (passer for 8 vCPU der Whisper=5 + et lett kall=1+1+1).
const MAX_TOTAL_WEIGHT: i16 = 8;

/// 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.
///
/// Alle handlere delegerer til CLI-verktøy (Command::new("synops-X"))
/// i tråd med Unix-filosofien. Unntaket er ai_process som fortsatt
/// kjører inline (mangler CLI-verktøy, planlagt i fremtidig oppgave).
///
/// Ref: docs/retninger/unix_filosofi.md
async fn dispatch(
    job: &JobRow,
    db: &PgPool,
    cas: &CasStore,
    index_cache: &IndexCache,
    whisper_url: &str,
) -> Result<serde_json::Value, String> {
    match job.job_type.as_str() {
        "whisper_transcribe" => {
            transcribe::handle_whisper_job(job, cas, whisper_url).await
        }
        "agent_respond" => {
            agent::handle_agent_respond(job, db).await
        }
        "suggest_edges" => {
            ai_edges::handle_suggest_edges(job, db).await
        }
        "summarize_communication" => {
            summarize::handle_summarize_communication(job, db).await
        }
        "tts_generate" => {
            tts::handle_tts_job(job, db).await
        }
        "audio_process" => {
            audio::handle_audio_process_job(job, db, cas).await
        }
        "ai_process" => {
            ai_process::handle_ai_process(job, db).await
        }
        "render_article" => {
            handle_render_article(job, cas).await
        }
        "render_index" => {
            handle_render_index(job, cas).await
        }
        // PG-skriveoperasjoner (oppgave 12.3): retry med backoff + dead letter queue
        "pg_insert_node" => {
            pg_writes::handle_insert_node(job, db).await
        }
        "pg_insert_edge" => {
            pg_writes::handle_insert_edge(job, db, index_cache).await
        }
        "pg_update_node" => {
            pg_writes::handle_update_node(job, db).await
        }
        "pg_delete_node" => {
            pg_writes::handle_delete_node(job, db).await
        }
        "pg_delete_edge" => {
            pg_writes::handle_delete_edge(job, db, index_cache).await
        }
        // Orchestration: trigger-evaluering har lagt jobben i kø,
        // men utførelsen implementeres i oppgave 24.3.
        // Foreløpig logger vi og returnerer OK.
        "orchestrate" => {
            let orch_id = job.payload.get("orchestration_id")
                .and_then(|v| v.as_str())
                .unwrap_or("ukjent");
            tracing::info!(
                orchestration_id = %orch_id,
                "Orchestrate-jobb mottatt (utførelse kommer i oppgave 24.3)"
            );
            Ok(serde_json::json!({
                "status": "pending_implementation",
                "orchestration_id": orch_id,
                "message": "Orchestration execution not yet implemented (task 24.3)"
            }))
        }
        other => Err(format!("Ukjent jobbtype: {other}")),
    }
}

/// Synops-render binary path.
fn render_bin() -> String {
    std::env::var("SYNOPS_RENDER_BIN")
        .unwrap_or_else(|_| "synops-render".to_string())
}

/// Handler for `render_article`-jobb — delegerer til synops-render CLI.
///
/// Payload: `{ "node_id": "...", "collection_id": "..." }`
/// CLI-verktøyet gjør Tera-rendering, CAS-lagring og metadata-oppdatering.
async fn handle_render_article(
    job: &JobRow,
    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")?;

    let bin = render_bin();
    let mut cmd = tokio::process::Command::new(&bin);

    cmd.arg("--node-id").arg(node_id.to_string())
        .arg("--collection-id").arg(collection_id.to_string())
        .arg("--render-type").arg("article")
        .arg("--write");

    cli_dispatch::set_database_url(&mut cmd)?;
    cmd.env("CAS_ROOT", cas.root().to_string_lossy().to_string());

    tracing::info!(
        node_id = %node_id,
        collection_id = %collection_id,
        bin = %bin,
        "Starter synops-render (article)"
    );

    let result = cli_dispatch::run_cli_tool(&bin, &mut cmd).await?;

    tracing::info!(
        node_id = %node_id,
        html_hash = result["html_hash"].as_str().unwrap_or("n/a"),
        "synops-render (article) fullført"
    );

    Ok(result)
}

/// Handler for `render_index`-jobb — delegerer til synops-render CLI.
///
/// Payload: `{ "collection_id": "..." }`
/// CLI-verktøyet gjør Tera-rendering, CAS-lagring og metadata-oppdatering.
async fn handle_render_index(
    job: &JobRow,
    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")?;

    let bin = render_bin();
    let mut cmd = tokio::process::Command::new(&bin);

    cmd.arg("--node-id").arg(collection_id.to_string())
        .arg("--render-type").arg("index")
        .arg("--write");

    cli_dispatch::set_database_url(&mut cmd)?;
    cmd.env("CAS_ROOT", cas.root().to_string_lossy().to_string());

    tracing::info!(
        collection_id = %collection_id,
        bin = %bin,
        "Starter synops-render (index)"
    );

    let result = cli_dispatch::run_cli_tool(&bin, &mut cmd).await?;

    tracing::info!(
        collection_id = %collection_id,
        html_hash = result["html_hash"].as_str().unwrap_or("n/a"),
        "synops-render (index) fullført"
    );

    Ok(result)
}

// =============================================================================
// Admin-API: spørring, retry og avbryt (oppgave 15.3)
// =============================================================================

/// Rad med alle felter for admin-oversikt.
#[derive(sqlx::FromRow, Debug, Serialize)]
pub struct JobDetail {
    pub id: Uuid,
    pub collection_node_id: Option<Uuid>,
    pub job_type: String,
    pub payload: serde_json::Value,
    pub status: String,
    pub priority: i16,
    pub result: Option<serde_json::Value>,
    pub error_msg: Option<String>,
    pub attempts: i16,
    pub max_attempts: i16,
    pub created_at: DateTime<Utc>,
    pub started_at: Option<DateTime<Utc>>,
    pub completed_at: Option<DateTime<Utc>>,
    pub scheduled_for: DateTime<Utc>,
}

/// Hent jobber med valgfri filtrering på status, type og samling.
/// Returnerer nyeste først, begrenset til `limit` rader.
pub async fn list_jobs(
    db: &PgPool,
    status_filter: Option<&str>,
    type_filter: Option<&str>,
    collection_filter: Option<Uuid>,
    limit: i64,
    offset: i64,
) -> Result<Vec<JobDetail>, sqlx::Error> {
    // Bygg dynamisk WHERE-klausul
    let mut conditions: Vec<String> = Vec::new();

    if let Some(s) = status_filter {
        conditions.push(format!("status = '{s}'"));
    }
    if let Some(t) = type_filter {
        // Sanitize: kun alfanumeriske + underscore
        let safe: String = t.chars().filter(|c| c.is_alphanumeric() || *c == '_').collect();
        conditions.push(format!("job_type = '{safe}'"));
    }
    if let Some(cid) = collection_filter {
        conditions.push(format!("collection_node_id = '{cid}'"));
    }

    let where_clause = if conditions.is_empty() {
        String::new()
    } else {
        format!("WHERE {}", conditions.join(" AND "))
    };

    let query = format!(
        r#"SELECT id, collection_node_id, job_type, payload,
                  status::text as status, priority, result, error_msg,
                  attempts, max_attempts, created_at, started_at,
                  completed_at, scheduled_for
           FROM job_queue
           {where_clause}
           ORDER BY created_at DESC
           LIMIT {limit} OFFSET {offset}"#
    );

    sqlx::query_as::<_, JobDetail>(&query)
        .fetch_all(db)
        .await
}

/// Tell jobber per status (for dashboard-oppsummering).
#[derive(sqlx::FromRow, Serialize, Debug)]
pub struct JobCountByStatus {
    pub status: String,
    pub count: i64,
}

pub async fn count_by_status(db: &PgPool) -> Result<Vec<JobCountByStatus>, sqlx::Error> {
    sqlx::query_as::<_, JobCountByStatus>(
        "SELECT status::text as status, count(*) as count FROM job_queue GROUP BY status"
    )
    .fetch_all(db)
    .await
}

/// Hent distinkte jobbtyper (for filter-dropdown).
pub async fn distinct_job_types(db: &PgPool) -> Result<Vec<String>, sqlx::Error> {
    sqlx::query_scalar::<_, String>(
        "SELECT DISTINCT job_type FROM job_queue ORDER BY job_type"
    )
    .fetch_all(db)
    .await
}

/// Sett en feilet jobb tilbake til 'pending' for manuell retry.
/// Kun jobber med status 'error' eller 'retry' kan retryes.
pub async fn retry_job(db: &PgPool, job_id: Uuid) -> Result<bool, sqlx::Error> {
    let result = sqlx::query(
        r#"UPDATE job_queue
           SET status = 'pending',
               error_msg = NULL,
               scheduled_for = now(),
               attempts = 0
           WHERE id = $1
             AND status IN ('error', 'retry')"#
    )
    .bind(job_id)
    .execute(db)
    .await?;

    Ok(result.rows_affected() > 0)
}

/// Avbryt en ventende eller retry-jobb (sett til 'error' med melding).
/// Kjørende jobber kan ikke avbrytes via dette (de kjører allerede i en task).
pub async fn cancel_job(db: &PgPool, job_id: Uuid) -> Result<bool, sqlx::Error> {
    let result = sqlx::query(
        r#"UPDATE job_queue
           SET status = 'error',
               error_msg = 'Manuelt avbrutt av admin',
               completed_at = now()
           WHERE id = $1
             AND status IN ('pending', 'retry')"#
    )
    .bind(job_id)
    .execute(db)
    .await?;

    Ok(result.rows_affected() > 0)
}

/// Starter worker-loopen som poller job_queue.
/// Kjører som en bakgrunnsoppgave i tokio.
///
/// Ressursstyring (oppgave 15.5):
/// - Concurrency-kontroll via semaphore (maks 3 samtidige jobber)
/// - Prioritetsregler fra job_priority_rules-tabellen
/// - LiveKit-bevisst resource governor: nedprioriterer/blokkerer tunge
///   jobber når LiveKit-rom er aktive
/// - CPU-vektbasert kapasitetskontroll (MAX_TOTAL_WEIGHT)
///
/// Respekterer vedlikeholdsmodus: når `maintenance.is_active()` er true,
/// slutter workeren å dequeue nye jobber (kjørende jobber fullføres).
pub fn start_worker(
    db: PgPool,
    cas: CasStore,
    index_cache: IndexCache,
    maintenance: MaintenanceState,
    priority_rules: PriorityRules,
) {
    let whisper_url = std::env::var("WHISPER_URL")
        .unwrap_or_else(|_| "http://faster-whisper:8000".to_string());

    // Semaphore for maks 3 samtidige jobber (doc: --max-concurrent 3)
    let semaphore = Arc::new(Semaphore::new(3));

    // Cache LiveKit-status med 10-sekunders TTL for å unngå
    // å spørre PG på hver poll-iterasjon
    let livekit_cache: Arc<tokio::sync::RwLock<(bool, std::time::Instant)>> =
        Arc::new(tokio::sync::RwLock::new((false, std::time::Instant::now())));

    tokio::spawn(async move {
        tracing::info!("Jobbkø-worker startet (poll: 2s, max-concurrent: 3, max-weight: {MAX_TOTAL_WEIGHT})");

        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;
            }

            // Sjekk om vi har ledig kapasitet (semaphore)
            let permit = match semaphore.clone().try_acquire_owned() {
                Ok(p) => p,
                Err(_) => {
                    // Alle 3 slots er opptatt — vent litt
                    tokio::time::sleep(std::time::Duration::from_secs(1)).await;
                    continue;
                }
            };

            // Sjekk total CPU-vekt
            let current_weight = resources::total_running_weight(&db, &priority_rules).await;
            if current_weight >= MAX_TOTAL_WEIGHT {
                drop(permit);
                tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                continue;
            }

            // Oppdater LiveKit-cache (TTL: 10 sekunder)
            let livekit_active = {
                let cache = livekit_cache.read().await;
                if cache.1.elapsed() < std::time::Duration::from_secs(10) {
                    cache.0
                } else {
                    drop(cache);
                    let active = resources::has_active_livekit_rooms(&db).await;
                    let mut cache = livekit_cache.write().await;
                    *cache = (active, std::time::Instant::now());
                    active
                }
            };

            match dequeue(&db).await {
                Ok(Some(job)) => {
                    // Sjekk prioritetsregler for denne jobbtypen
                    let rule = priority_rules.get(&job.job_type).await;
                    let decision = resources::evaluate_job(&rule, livekit_active);

                    // Sjekk om jobben skal utsettes (LiveKit-blokkering)
                    if decision.should_defer {
                        tracing::info!(
                            job_id = %job.id,
                            job_type = %job.job_type,
                            "Jobb utsatt — blokkert under aktiv LiveKit-sesjon"
                        );
                        // Sett tilbake til pending med kort delay
                        let _ = sqlx::query(
                            "UPDATE job_queue SET status = 'pending', started_at = NULL, attempts = attempts - 1, scheduled_for = now() + interval '30 seconds' WHERE id = $1"
                        )
                        .bind(job.id)
                        .execute(&db)
                        .await;
                        drop(permit);
                        tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                        continue;
                    }

                    // Sjekk max_concurrent per type
                    if rule.max_concurrent > 0 {
                        let running = resources::count_running_of_type(&db, &job.job_type)
                            .await
                            .unwrap_or(0);
                        // running inkluderer den vi nettopp satte til 'running',
                        // så sjekk mot max_concurrent
                        if running > rule.max_concurrent as i64 {
                            tracing::debug!(
                                job_type = %job.job_type,
                                running = running,
                                max = rule.max_concurrent,
                                "Max concurrent nådd for jobbtype — utsetter"
                            );
                            let _ = sqlx::query(
                                "UPDATE job_queue SET status = 'pending', started_at = NULL, attempts = attempts - 1, scheduled_for = now() + interval '5 seconds' WHERE id = $1"
                            )
                            .bind(job.id)
                            .execute(&db)
                            .await;
                            drop(permit);
                            tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                            continue;
                        }
                    }

                    // Sjekk at ny jobb ikke sprenger vektgrensen
                    if current_weight + rule.cpu_weight > MAX_TOTAL_WEIGHT {
                        tracing::debug!(
                            job_type = %job.job_type,
                            weight = rule.cpu_weight,
                            current = current_weight,
                            max = MAX_TOTAL_WEIGHT,
                            "CPU-vektgrense nådd — utsetter tung jobb"
                        );
                        let _ = sqlx::query(
                            "UPDATE job_queue SET status = 'pending', started_at = NULL, attempts = attempts - 1, scheduled_for = now() + interval '5 seconds' WHERE id = $1"
                        )
                        .bind(job.id)
                        .execute(&db)
                        .await;
                        drop(permit);
                        tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                        continue;
                    }

                    tracing::info!(
                        job_id = %job.id,
                        job_type = %job.job_type,
                        attempt = job.attempts,
                        weight = rule.cpu_weight,
                        livekit = livekit_active,
                        "Behandler jobb"
                    );

                    // Kjør jobben i en egen tokio-task (frigjør poll-loopen)
                    let db2 = db.clone();
                    let cas2 = cas.clone();
                    let index_cache2 = index_cache.clone();
                    let whisper_url2 = whisper_url.clone();
                    let timeout_secs = if rule.timeout_seconds > 0 {
                        rule.timeout_seconds as u64
                    } else {
                        600 // 10 min default
                    };

                    tokio::spawn(async move {
                        // Hold semaphore-permit til jobben er ferdig
                        let _permit = permit;

                        let result = tokio::time::timeout(
                            std::time::Duration::from_secs(timeout_secs),
                            dispatch(&job, &db2, &cas2, &index_cache2, &whisper_url2),
                        )
                        .await;

                        match result {
                            Ok(Ok(res)) => {
                                if let Err(e) = complete_job(&db2, job.id, res).await {
                                    tracing::error!(job_id = %job.id, error = %e, "Kunne ikke markere jobb som fullført");
                                } else {
                                    tracing::info!(job_id = %job.id, "Jobb fullført");
                                }
                            }
                            Ok(Err(err)) => {
                                tracing::error!(job_id = %job.id, error = %err, "Jobb feilet");
                                if let Err(e) = fail_job(&db2, &job, &err).await {
                                    tracing::error!(job_id = %job.id, error = %e, "Kunne ikke markere jobb som feilet");
                                }
                            }
                            Err(_) => {
                                let msg = format!("Jobb tidsavbrutt etter {timeout_secs}s");
                                tracing::error!(job_id = %job.id, "{msg}");
                                if let Err(e) = fail_job(&db2, &job, &msg).await {
                                    tracing::error!(job_id = %job.id, error = %e, "Kunne ikke markere tidsavbrutt jobb");
                                }
                            }
                        }
                    });

                    // Ikke vent — poll umiddelbart for neste jobb
                    continue;
                }
                Ok(None) => {
                    drop(permit);
                    // Ingen ventende jobber — vent før neste poll
                    tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                }
                Err(e) => {
                    drop(permit);
                    tracing::error!(error = %e, "Feil ved polling av jobbkø");
                    tokio::time::sleep(std::time::Duration::from_secs(5)).await;
                }
            }
        }
    });
}