use tokio::task::JoinHandle;
use tracing::info;

use pom::alerts::Alerter;
use pom::checks::{http, ssh_banner};
use pom::config::Config;
use pom::db;
use pom::types::{HealthStatus, LatencyStats};

use super::super::incident::{incident_action, IncidentAction};

pub(crate) fn spawn_health_tasks(
    config: &Config,
    pool: &sqlx::SqlitePool,
    cancel: &tokio_util::sync::CancellationToken,
    alerter: &Option<Alerter>,
) -> Vec<JoinHandle<()>> {
    let default_interval = config.serve.interval_secs;
    let mut handles = Vec::new();

    for name in config.target_names() {
        let target_config = config.get_target(&name).unwrap().clone();
        if let Some(health_config) = target_config.health {
            let interval_secs = health_config.interval_secs.unwrap_or(default_interval);
            let pool = pool.clone();
            let name = name.clone();
            let label = target_config.label.clone();
            let alerter = alerter.clone();
            let cancel = cancel.clone();
            let trending_config = health_config.trending.clone();

            info!("{name}: health check every {interval_secs}s");

            handles.push(tokio::spawn(async move {
                let mut interval = tokio::time::interval(
                    std::time::Duration::from_secs(interval_secs),
                );
                let expect = health_config.expect.as_ref();
                let mut in_drift = false;
                interval.tick().await; // consume immediate first tick
                loop {
                    tokio::select! {
                        _ = cancel.cancelled() => break,
                        _ = interval.tick() => {}
                    }
                    let previous = db::get_latest_health(&pool, &name).await.ok().flatten();
                    let snapshot = http::check_health(&name, &health_config, expect).await;
                    info!("{}: {} ({}ms)", name, snapshot.status, snapshot.response_time_ms);
                    if let Err(e) = db::insert_health_check(&pool, &snapshot).await {
                        tracing::error!("{name}: failed to store health check: {e}");
                    }

                    // Fire alerts on status transitions
                    if let Some(ref alerter) = alerter
                        && let Some(ref prev) = previous
                        && prev.status != snapshot.status
                    {
                        let from = prev.status.to_string();
                        let to = snapshot.status.to_string();
                        if snapshot.status == HealthStatus::Operational {
                            alerter.send_health_recovery(&name, &label, &from).await;
                        } else {
                            alerter.send_health_alert(
                                &name,
                                &label,
                                &from,
                                &to,
                                snapshot.error.as_deref(),
                            ).await;
                        }
                    }

                    // Track incidents on status transitions
                    if let Some(ref prev) = previous {
                        match incident_action(prev.status, snapshot.status) {
                            IncidentAction::None => {}
                            IncidentAction::Open => {
                                if let Err(e) = db::insert_incident(&pool, &name, &prev.status.to_string(), &snapshot.status.to_string()).await {
                                    tracing::error!("{name}: failed to open incident: {e}");
                                }
                            }
                            IncidentAction::Close => {
                                if let Err(e) = db::close_open_incidents(&pool, &name).await {
                                    tracing::error!("{name}: failed to close incidents: {e}");
                                }
                            }
                            IncidentAction::CloseAndOpen => {
                                if let Err(e) = db::close_open_incidents(&pool, &name).await {
                                    tracing::error!("{name}: failed to close incidents: {e}");
                                }
                                if let Err(e) = db::insert_incident(&pool, &name, &prev.status.to_string(), &snapshot.status.to_string()).await {
                                    tracing::error!("{name}: failed to open incident: {e}");
                                }
                            }
                        }
                    }

                    // Latency drift detection
                    if let Some(ref trending) = trending_config
                        && snapshot.status == HealthStatus::Operational
                    {
                        let baseline_cutoff = (chrono::Utc::now()
                            - chrono::Duration::hours(trending.baseline_window_hours as i64))
                            .to_rfc3339();
                        let baseline_data = db::get_response_times(&pool, &name, &baseline_cutoff)
                            .await
                            .unwrap_or_default();
                        let operational_times: Vec<i64> = baseline_data.iter()
                            .filter(|(_, ms)| *ms > 0)
                            .map(|(_, ms)| *ms)
                            .collect();
                        let baseline = LatencyStats::from_times(&operational_times);
                        let recent = db::get_recent_response_times(&pool, &name, 3)
                            .await
                            .unwrap_or_default();

                        if let Some(ref bl) = baseline {
                            if let Some(msg) = http::detect_latency_drift(&recent, bl, trending.spike_threshold) {
                                if !in_drift {
                                    info!("{name}: {msg}");
                                    if let Some(ref alerter) = alerter {
                                        alerter.send_latency_drift_alert(&name, &label, &msg).await;
                                    }
                                    in_drift = true;
                                }
                            } else if in_drift {
                                info!("{name}: latency drift recovered");
                                if let Some(ref alerter) = alerter {
                                    alerter.send_latency_recovery(&name, &label).await;
                                }
                                in_drift = false;
                            }
                        }
                    }
                }
            }));
        }
    }

    // SSH banner checks — stored as health check entries with target name "{name}:ssh"
    for name in config.target_names() {
        let target_config = config.get_target(&name).unwrap().clone();
        if let Some(ssh_config) = target_config.ssh_banner {
            let interval_secs = default_interval;
            let pool = pool.clone();
            let check_name = format!("{name}:ssh");
            let label = target_config.label.clone();
            let alerter = alerter.clone();
            let cancel = cancel.clone();

            info!("{check_name}: SSH banner check every {interval_secs}s");

            handles.push(tokio::spawn(async move {
                let mut interval = tokio::time::interval(
                    std::time::Duration::from_secs(interval_secs),
                );
                interval.tick().await;
                loop {
                    tokio::select! {
                        _ = cancel.cancelled() => break,
                        _ = interval.tick() => {}
                    }
                    let previous = db::get_latest_health(&pool, &check_name).await.ok().flatten();
                    let snapshot = ssh_banner::check_ssh_banner(&check_name, &ssh_config).await;
                    info!("{}: {} ({}ms)", check_name, snapshot.status, snapshot.response_time_ms);
                    if let Err(e) = db::insert_health_check(&pool, &snapshot).await {
                        tracing::error!("{check_name}: failed to store SSH banner check: {e}");
                    }

                    if let Some(ref alerter) = alerter
                        && let Some(ref prev) = previous
                        && prev.status != snapshot.status
                    {
                        let from = prev.status.to_string();
                        let to = snapshot.status.to_string();
                        if snapshot.status == HealthStatus::Operational {
                            alerter.send_health_recovery(&check_name, &label, &from).await;
                        } else {
                            alerter.send_health_alert(
                                &check_name,
                                &label,
                                &from,
                                &to,
                                snapshot.error.as_deref(),
                            ).await;
                        }
                    }
                }
            }));
        }
    }

    handles
}