import { fleetSettings } from '../settings.js';
import { db } from '../db/index.js';
import { emit } from './bus.js';
import { requestRestart } from '../provisioning/index.js';
import { pruneHostObservations } from '../hosts/index.js';

interface PendingRow {
    deployment_id: string; server: string; restart_state: string;
    restarted_at: string | null; files_changed: number;
    players: number | null; error: string | null;
}
type SweepResult = { checked: number; restarted: number; healthy: number; held: number; failed: number };
let sweepInFlight: Promise<SweepResult> | null = null;
const nowIso = () => new Date().toISOString();

/** Submit activation requests and mirror their results. Provisioning owns all execution. */
export function sweep(): Promise<SweepResult> {
    if (sweepInFlight) return sweepInFlight;
    sweepInFlight = runSweep().finally(() => { sweepInFlight = null; });
    return sweepInFlight;
}
async function runSweep(): Promise<SweepResult> {
    pruneHostObservations();
    const pending = db().prepare(`SELECT ds.* FROM deployment_servers ds JOIN deployments d ON d.id = ds.deployment_id
        WHERE ds.server_deleted_at IS NULL AND ds.restart_state IN ('pending','failed') ORDER BY d.started_at, d.id, ds.server`).all() as PendingRow[];
    const result: SweepResult = { checked: 0, restarted: 0, healthy: 0, held: 0, failed: 0 };
    for (const row of pending) {
        if (!row.files_changed) continue; // A failed file write is not a restart request.
        const operation = requestRestart(row.server, { kind: 'campaign', id: row.deployment_id });
        result.checked++;
        const state = operation.state === 'done' ? 'done'
            : ['failed','interrupted','cancelled'].includes(operation.state) ? 'failed' : 'pending';
        const restartedAt = ['awaiting-health','done'].includes(operation.state) ? operation.submitted_at : row.restarted_at;
        if (restartedAt && !row.restarted_at) result.restarted++;
        if (state === 'done') result.healthy++;
        if (state === 'pending') result.held++;
        if (state === 'failed') result.failed++;
        const error = state === 'done' ? null : operation.error ?? operation.stage;
        db().prepare(`UPDATE deployment_servers SET restart_state = ?, checked_at = ?, players = ?, error = ?,
            attempts = attempts + CASE WHEN ? IS NOT NULL AND checked_at IS NOT ? THEN 1 ELSE 0 END,
            restarted_at = COALESCE(restarted_at, ?) WHERE deployment_id = ? AND server = ?`)
            .run(state, operation.checked_at, operation.players, error, operation.checked_at, operation.checked_at, restartedAt, row.deployment_id, row.server);
        if (state !== row.restart_state || operation.players !== row.players || error !== row.error) {
            emit({ type: 'server-state', deploymentId: row.deployment_id, server: row.server, state, players: operation.players, error });
        }
    }
    db().prepare(`UPDATE deployments SET finished_at = ? WHERE finished_at IS NULL AND NOT EXISTS (
        SELECT 1 FROM deployment_servers WHERE deployment_id = deployments.id AND server_deleted_at IS NULL AND restart_state IN ('pending','failed','held'))`).run(nowIso());
    db().prepare(`DELETE FROM deployments WHERE started_at < ?
        AND NOT EXISTS (SELECT 1 FROM watchdog_actions WHERE campaign_id = deployments.id) AND NOT EXISTS (
        SELECT 1 FROM deployment_servers WHERE deployment_id = deployments.id AND server_deleted_at IS NULL AND restart_state IN ('pending','failed','held'))`)
        .run(new Date(Date.now() - fleetSettings().deployKeepDays * 86_400_000).toISOString());
    emit({ type: 'sweep-tick', frozen: false });
    return result;
}