//! Background tasks: CRDT-event bridge, auto-assign subscriber, unified tick
//! loop, gateway relay, and startup reconciliation.

use crate::agents::{AgentPool, ReconciliationEvent};
use crate::config;
use crate::gateway_relay;
use crate::io;
use crate::pipeline_state;
use crate::service;
use crate::service::status::StatusBroadcaster;
use std::path::PathBuf;
use std::sync::Arc;
use tokio::sync::broadcast;

/// Bridge CRDT state-transition events to the watcher broadcast channel and
/// spawn the auto-assign subscriber that triggers on active-stage transitions.
pub(crate) fn spawn_event_bridges(
    watcher_tx: broadcast::Sender<io::watcher::WatcherEvent>,
    project_root: Option<PathBuf>,
    agents: Arc<AgentPool>,
) {
    // CRDT → watcher bridge: translate CRDT stage-transition events into
    // WatcherEvent::WorkItem so downstream consumers (WebSocket, auto-assign)
    // see a uniform stream regardless of whether the event originated from the
    // filesystem watcher or from a CRDT sync peer.
    {
        let crdt_watcher_tx = watcher_tx.clone();
        let crdt_prune_root = project_root.clone();
        if let Some(mut crdt_rx) = crate::crdt_state::subscribe() {
            tokio::spawn(async move {
                while let Ok(evt) = crdt_rx.recv().await {
                    if crate::pipeline_state::Stage::from_dir(&evt.to_stage)
                        .is_some_and(|s| matches!(s, crate::pipeline_state::Stage::Archived { .. }))
                        && let Some(root) = crdt_prune_root.as_ref().cloned()
                    {
                        let story_id = evt.story_id.clone();
                        tokio::task::spawn_blocking(move || {
                            if let Err(e) = crate::worktree::prune_worktree_sync(&root, &story_id) {
                                crate::slog!("[crdt] worktree prune failed for {story_id}: {e}");
                            }
                        });
                    }
                    let (action, commit_msg) =
                        io::watcher::stage_metadata(&evt.to_stage, &evt.story_id)
                            .unwrap_or(("update", format!("huskies: update {}", evt.story_id)));
                    let watcher_evt = io::watcher::WatcherEvent::WorkItem {
                        stage: evt.to_stage,
                        item_id: evt.story_id,
                        action: action.to_string(),
                        commit_msg,
                        from_stage: evt.from_stage,
                    };
                    let _ = crdt_watcher_tx.send(watcher_evt);
                }
            });
        }
    }

    // Auto-assign: trigger `auto_assign_available_work` whenever a work item
    // enters an active pipeline stage (2_current/, 3_qa/, 4_merge/).
    if let Some(root) = project_root {
        let watcher_auto_rx = watcher_tx.subscribe();
        let watcher_auto_agents = Arc::clone(&agents);
        tokio::spawn(async move {
            let mut rx = watcher_auto_rx;
            while let Ok(event) = rx.recv().await {
                if let io::watcher::WatcherEvent::WorkItem { ref stage, .. } = event
                    && pipeline_state::Stage::from_dir(stage.as_str())
                        .is_some_and(|s| s.is_active())
                {
                    crate::slog!(
                        "[auto-assign] CRDT transition detected in {stage}/; \
                         triggering auto-assign."
                    );
                    watcher_auto_agents.auto_assign_available_work(&root).await;
                }
            }
        });
    }
}

/// Spawn the unified 1-second background tick loop.
///
/// Fires due timers, runs the agent watchdog every 30 ticks, and promotes
/// done→archived items every `sweep_interval_secs` ticks.
pub(crate) fn spawn_tick_loop(
    agents: Arc<AgentPool>,
    timer_store: Arc<service::timer::TimerStore>,
    root: Option<PathBuf>,
) {
    let sweep_cfg = root
        .as_ref()
        .and_then(|r| config::ProjectConfig::load(r).ok())
        .map(|c| c.watcher)
        .unwrap_or_default();
    let sweep_every = sweep_cfg.sweep_interval_secs.max(1);
    let done_retention = std::time::Duration::from_secs(sweep_cfg.done_retention_secs);
    let pending_count = timer_store.list().len();
    crate::slog!("[tick] Unified tick loop started; {pending_count} pending timer(s)");

    tokio::spawn(async move {
        let mut interval = tokio::time::interval(std::time::Duration::from_secs(1));
        let mut tick_count: u64 = 0;
        loop {
            interval.tick().await;
            tick_count = tick_count.wrapping_add(1);

            // Timer: fire due timers every second.
            if let Some(ref r) = root {
                let result = service::timer::tick_once(&timer_store, &agents, r).await;
                if let Err(msg) = result {
                    crate::slog_error!("[tick] Timer tick panicked: {msg}");
                }
            }

            // Watchdog: detect orphaned Running agents every 30 ticks.
            if tick_count.is_multiple_of(30) {
                let found = agents.run_watchdog_pass(root.as_deref());
                if found > 0 {
                    crate::slog!(
                        "[tick] {found} orphaned agent(s) detected; triggering auto-assign."
                    );
                    if let Some(ref r) = root {
                        agents.auto_assign_available_work(r).await;
                    }
                }
            }

            // Sweep: promote done→archived every sweep_interval_secs ticks.
            if tick_count.is_multiple_of(sweep_every) {
                io::watcher::sweep_done_to_archived(done_retention);
            }
        }
    });
}

/// Spawn the gateway relay task if `gateway_url` is configured in
/// `project.toml` or the `HUSKIES_GATEWAY_URL` environment variable.
pub(crate) fn spawn_gateway_relay(startup_root: &Option<PathBuf>, status: Arc<StatusBroadcaster>) {
    let relay_gateway_url = startup_root
        .as_ref()
        .and_then(|r| config::ProjectConfig::load(r).ok())
        .and_then(|c| c.gateway_url)
        .or_else(|| std::env::var("HUSKIES_GATEWAY_URL").ok())
        .unwrap_or_default();

    if !relay_gateway_url.is_empty() {
        let relay_project_name = startup_root
            .as_ref()
            .and_then(|r| config::ProjectConfig::load(r).ok())
            .and_then(|c| c.gateway_project)
            .or_else(|| std::env::var("HUSKIES_GATEWAY_PROJECT").ok())
            .or_else(|| {
                startup_root
                    .as_ref()
                    .and_then(|r| r.file_name())
                    .map(|n| n.to_string_lossy().into_owned())
            })
            .unwrap_or_else(|| "project".to_string());

        gateway_relay::spawn_relay_task(
            relay_gateway_url,
            relay_project_name,
            status,
            reqwest::Client::new(),
        );
    }
}

/// Spawn the startup reconciliation task: reconcile any stories whose agent
/// work was committed while the server was offline, then auto-assign free agents.
pub(crate) fn spawn_startup_reconciliation(
    startup_root: Option<PathBuf>,
    startup_agents: Arc<AgentPool>,
    startup_reconciliation_tx: broadcast::Sender<ReconciliationEvent>,
) {
    if let Some(root) = startup_root {
        tokio::spawn(async move {
            crate::slog!("[startup] Reconciling completed worktrees from previous session.");
            startup_agents
                .reconcile_on_startup(&root, &startup_reconciliation_tx)
                .await;
            crate::slog!("[auto-assign] Scanning pipeline stages for unassigned work.");
            startup_agents.auto_assign_available_work(&root).await;
        });
    }
}