//! Unified scheduler that manages all recurring background jobs.
//!
//! Replaces the separate pipeline_scheduler, monitor, and cookie_refresh spawn loops
//! with a single loop backed by persistent state in the `scheduler_state` DB table.

use std::time::Duration;

use actix_web::web;
use chrono::Utc;

use shanty_db::queries;

use crate::state::AppState;

/// Spawn the unified scheduler background loop.
pub fn spawn(state: web::Data<AppState>) {
    tokio::spawn(async move {
        // Initialize scheduler state rows in DB with next_run_at pre-populated
        for job_name in ["pipeline", "monitor", "cookie_refresh"] {
            match queries::scheduler_state::get_or_create(state.db.conn(), job_name).await {
                Ok(job) => {
                    if job.next_run_at.is_none() {
                        let (enabled, interval_secs) = read_job_config(&state, job_name).await;
                        if enabled {
                            let next =
                                Utc::now().naive_utc() + chrono::Duration::seconds(interval_secs);
                            let _ = queries::scheduler_state::update_next_run(
                                state.db.conn(),
                                job_name,
                                Some(next),
                            )
                            .await;
                        }
                    }
                }
                Err(e) => {
                    tracing::error!(job = job_name, error = %e, "failed to init scheduler state");
                }
            }
        }

        loop {
            // Check each job
            check_and_run_job(&state, "pipeline", run_pipeline_job).await;
            check_and_run_job(&state, "monitor", run_monitor_job).await;
            check_and_run_job(&state, "cookie_refresh", run_cookie_refresh_job).await;

            // Poll every 30 seconds
            tokio::time::sleep(Duration::from_secs(30)).await;
        }
    });
}

async fn check_and_run_job<F, Fut>(state: &web::Data<AppState>, job_name: &str, run_fn: F)
where
    F: FnOnce(web::Data<AppState>) -> Fut,
    Fut: std::future::Future<Output = Result<String, String>>,
{
    let job = match queries::scheduler_state::get_or_create(state.db.conn(), job_name).await {
        Ok(j) => j,
        Err(e) => {
            tracing::error!(job = job_name, error = %e, "failed to read scheduler state");
            return;
        }
    };

    // Read config to check if enabled and get interval
    let (config_enabled, interval_secs) = read_job_config(state, job_name).await;

    // If config says disabled, ensure DB state reflects it
    if !config_enabled {
        if job.enabled {
            let _ = queries::scheduler_state::set_enabled(state.db.conn(), job_name, false).await;
            let _ =
                queries::scheduler_state::update_next_run(state.db.conn(), job_name, None).await;
        }
        return;
    }

    // If DB says disabled (e.g. user skipped), re-enable from config
    if !job.enabled {
        let _ = queries::scheduler_state::set_enabled(state.db.conn(), job_name, true).await;
    }

    let now = Utc::now().naive_utc();

    // If no next_run_at is set, schedule one
    if job.next_run_at.is_none() {
        let next = now + chrono::Duration::seconds(interval_secs);
        let _ =
            queries::scheduler_state::update_next_run(state.db.conn(), job_name, Some(next)).await;
        return;
    }

    // Check if it's time to run
    let next_run = job.next_run_at.unwrap();
    if now < next_run {
        return;
    }

    // Time to run!
    tracing::info!(job = job_name, "scheduled job starting");

    let result = run_fn(state.clone()).await;

    let result_str = match &result {
        Ok(msg) => {
            tracing::info!(job = job_name, result = %msg, "scheduled job complete");
            format!("ok: {msg}")
        }
        Err(e) => {
            tracing::error!(job = job_name, error = %e, "scheduled job failed");
            format!("error: {e}")
        }
    };

    // Update last run and schedule next
    let _ = queries::scheduler_state::update_last_run(state.db.conn(), job_name, &result_str).await;
    let next = Utc::now().naive_utc() + chrono::Duration::seconds(interval_secs);
    let _ = queries::scheduler_state::update_next_run(state.db.conn(), job_name, Some(next)).await;
}

async fn read_job_config(state: &web::Data<AppState>, job_name: &str) -> (bool, i64) {
    let cfg = state.config.read().await;
    match job_name {
        "pipeline" => (
            cfg.scheduling.pipeline_enabled,
            i64::from(cfg.scheduling.pipeline_interval_hours.max(1)) * 3600,
        ),
        "monitor" => (
            cfg.scheduling.monitor_enabled,
            i64::from(cfg.scheduling.monitor_interval_hours.max(1)) * 3600,
        ),
        "cookie_refresh" => (
            cfg.download.cookie_refresh_enabled,
            i64::from(cfg.download.cookie_refresh_hours.max(1)) * 3600,
        ),
        _ => (false, 3600),
    }
}

async fn run_pipeline_job(state: web::Data<AppState>) -> Result<String, String> {
    let pipeline_id = crate::pipeline::trigger_pipeline(&state)
        .await
        .map_err(|e| e.to_string())?;
    Ok(format!("pipeline triggered: {pipeline_id}"))
}

async fn run_monitor_job(state: web::Data<AppState>) -> Result<String, String> {
    let stats = crate::monitor::check_monitored_artists(&state)
        .await
        .map_err(|e| e.to_string())?;
    Ok(format!(
        "{} artists checked, {} new releases, {} tracks added",
        stats.artists_checked, stats.new_releases_found, stats.tracks_added
    ))
}

async fn run_cookie_refresh_job(_state: web::Data<AppState>) -> Result<String, String> {
    crate::cookie_refresh::run_refresh().await
}