import { maintenanceAllowed } from '../maintenance/policies.js';
import { resolveRecoveredHealthOperation } from '../maintenance/recovery.js';
import { db } from '../db/index.js';
import { provisioningCancelled } from './cancellation.js';
import { komodoConfigured, rconConfigured } from '../config.js';
import { getServer } from '../fleet/servers.js';
import { deploymentStage, finishDeployment, REMOVING_SERVER } from './history.js';
import { processCreations, processDestructions, rebuildServer } from './instances.js';
import { komodoInspectHealthy, komodoRuntimeAction } from '../integrations/komodo.js';
import { latestGameSubmission, probePlayerEvidence } from '../fleet/status-evidence.js';
import { refreshRestartRollout, restartInRollout, rolloutBlocker } from './restarts.js';
import { cancelProvisioning } from './requests.js';
import type { RuntimeAction } from '../../provisioning.js';
import type { ProvisioningBlocker } from '../../provisioning-detail.js';
import { recordProgress } from './progress.js';
import { nativeInstance, nativeDeployment } from '../backends/native.js';
import { processNativeProvisioning } from './native.js';
import { trackActivity } from '../pipeline/activity.js';

const stoppedStates = new Set(['stopped', 'exited', 'created', 'dead']);
export const isStopped = (state?: string) => stoppedStates.has(state?.toLowerCase() ?? '');

interface Source { kind: 'campaign' | 'beta' | 'maintenance' | 'watchdog'; source_id: string }
const sourcesFor = (id: string) => db().prepare('SELECT kind, source_id FROM provisioning_sources WHERE operation_id = ?').all(id) as Source[];
const priority = (sources: Source[]) => sources.some(s => s.kind === 'watchdog') ? 2 : sources.some(s => s.kind === 'beta') ? 0 : sources.some(s => s.kind === 'campaign') ? 1 : sources.some(s => s.kind === 'maintenance') ? 3 : 2;

/** Source work may hold or withdraw a request, but never executes it. */
function sourceEligibility(operation: Operation, onHold?: (source: Source) => void): 'ready' | 'held' | 'cancelled' {
    const sources = sourcesFor(operation.id);
    if (!sources.length) return 'ready';
    // Watchdog intent gates every linked source, including its drift campaign.
    for (const source of sources.filter(source => source.kind === 'watchdog')) {
        if (!db().prepare("SELECT 1 FROM watchdog_incidents WHERE id = ? AND server = ? AND server_deleted_at IS NULL AND state IN ('open','recovering')").get(source.source_id, operation.server)
            || getServer(operation.server)?.desired_state === 'stopped') return 'cancelled';
        const incident = db().prepare('SELECT kind FROM watchdog_incidents WHERE id = ?').get(source.source_id) as { kind: 'health' | 'drift' };
        if (!maintenanceAllowed(incident.kind)) { onHold?.(source); return 'held'; }
    }
    let held = false;
    let ready = false;
    for (const source of sources) {
        if (source.kind === 'campaign') {
            const row = db().prepare('SELECT restart_state, files_changed, provisioning_id FROM deployment_servers WHERE deployment_id = ? AND server = ? AND server_deleted_at IS NULL')
                .get(source.source_id, operation.server) as { restart_state: string; files_changed: number; provisioning_id: string } | undefined;
            if (row?.provisioning_id !== operation.id || !row.files_changed) continue;
            if (['pending','failed'].includes(row.restart_state)) ready = true;
            if (['held','manual'].includes(row.restart_state)) { held = true; onHold?.(source); }
        } else if (source.kind === 'beta') {
            const row = db().prepare(`SELECT b.state, bs.stage, bs.provisioning_id, p.outcome FROM beta_servers bs JOIN betas b ON b.id = bs.beta_id
                LEFT JOIN beta_test_plans p ON p.beta_id = b.id WHERE bs.beta_id = ? AND bs.server = ? AND bs.server_deleted_at IS NULL`)
                .get(source.source_id, operation.server) as { state: string; stage: string; provisioning_id: string; outcome: string | null } | undefined;
            if (row?.provisioning_id !== operation.id || !['running','ready-promote'].includes(row.state)) continue;
            if (!['awaiting-empty','restarting','awaiting-health'].includes(row.stage)) continue;
            if (!row.outcome || ['active','passed'].includes(row.outcome)) ready = true;
            if (row.outcome === 'paused') { held = true; onHold?.(source); }
        } else if (source.kind === 'maintenance') {
            const row = db().prepare('SELECT state, provisioning_id, kind, origin FROM maintenance_jobs WHERE id = ? AND server_deleted_at IS NULL').get(source.source_id) as { state: string; provisioning_id: string; kind: string; origin: string } | undefined;
            if (row?.provisioning_id === operation.id && ['queued','restarting'].includes(row.state)) {
                if (getServer(operation.server)?.desired_state === 'stopped') return 'cancelled';
                if (!maintenanceAllowed() || (row.kind === 'update' && row.origin === 'automatic' && !maintenanceAllowed('updates'))) { onHold?.(source); return 'held'; }
                ready = true;
            }
        } else ready = true;
    }
    return held ? 'held' : ready ? 'ready' : 'cancelled';
}

function blocker(server: string, id: string, action: RuntimeAction): ProvisioningBlocker | null {
    const sources = sourcesFor(id);
    const rank = priority(sources);
    const others = db().prepare(`SELECT id, state, action, rowid FROM server_deployments WHERE server = ? AND id != ? AND server_deleted_at IS NULL
        AND state IN ('queued','waiting','running','awaiting-health')`).all(server, id) as { id: string; state: string; action: string; rowid: number }[];
    const own = db().prepare('SELECT rowid FROM server_deployments WHERE id = ?').get(id) as { rowid: number };
    const conflict = others.find(other => other.state !== 'waiting' || other.action === 'destroy'
        || priority(sourcesFor(other.id)) < rank || (priority(sourcesFor(other.id)) === rank && other.rowid < own.rowid));
    if (conflict) {
        return { code: 'operation-conflict', message: 'Waiting for another provisioning operation on this server', automatic: true,
            href: `/provisioning/${encodeURIComponent(conflict.id)}`, label: 'Blocking operation' };
    }
    // Beta activation must not wait on the campaign rows that the beta itself
    // holds. Campaign/maintenance callers likewise never block on their own job.
    const beta = rank > 0 ? db().prepare(`SELECT b.id FROM beta_servers bs JOIN betas b ON b.id = bs.beta_id
        WHERE bs.server = ? AND bs.server_deleted_at IS NULL AND b.state IN ('running','ready-promote') LIMIT 1`).get(server) as { id: string } | undefined : undefined;
    if (beta) return { code: 'beta-work', message: 'Waiting for beta work on this server', automatic: true, href: `/betas/${encodeURIComponent(beta.id)}`, label: 'Blocking beta' };
    const campaign = rank > 1 ? db().prepare(`SELECT ds.deployment_id FROM deployment_servers ds WHERE ds.server = ? AND ds.server_deleted_at IS NULL
        AND ds.restart_state IN ('pending','failed','held') AND (ds.provisioning_id IS NULL OR EXISTS (
            SELECT 1 FROM server_deployments d WHERE d.id = ds.provisioning_id AND d.state IN ('queued','waiting','running','awaiting-health')))
        AND NOT EXISTS (SELECT 1 FROM watchdog_actions a WHERE a.operation_id = ? AND a.campaign_id = ds.deployment_id)
        LIMIT 1`).get(server, id) as { deployment_id: string } | undefined : undefined;
    if (campaign) return { code: 'campaign-work', message: 'Waiting for campaign work on this server', automatic: true,
        href: `/campaigns/${encodeURIComponent(campaign.deployment_id)}`, label: 'Blocking campaign' };
    return rolloutBlocker(server, id, action);
}

interface Operation { id: string; server: string; action: RuntimeAction; state: string; stage: string }
let ticking: Promise<void> | null = null;
let awaitedPass: Promise<void> | null = null;
export function processProvisioning(options: { wait?: boolean } = {}): Promise<void> {
    if (options.wait !== false && awaitedPass) return awaitedPass;
    // Native jobs own their individual flights. A slow observation must not
    // prevent the next scheduler pass admitting newly arrived native work.
    const native = nativePass(options);
    if (!ticking) ticking = trackActivity('legacy-provisioning', 'Processing legacy provisioning', run)
        .finally(() => { ticking = null; });
    if (options.wait === false) {
        void ticking.catch(error => console.error('[worker] legacy provisioning error:', error));
        return native;
    }
    awaitedPass = Promise.all([native, ticking]).then(() => {}).finally(() => { awaitedPass = null; });
    return awaitedPass;
}

export const processLifecycle = processProvisioning;

function nativePass(options: { wait?: boolean }): Promise<void> {
    return processNativeProvisioning(operation => {
        if (operation.action === 'create') return null;
        if (operation.action === 'destroy') {
            const other = db().prepare(`SELECT id FROM server_deployments WHERE server=? AND id!=? AND server_deleted_at IS NULL
                AND (state='running' OR (state='awaiting-health' AND action NOT IN ('create','rebuild'))) LIMIT 1`).get(operation.server, operation.id);
            return other ? 'Waiting for the current server operation.' : null;
        }
        const typed = operation as Operation;
        const eligibility = sourceEligibility(typed);
        if (eligibility === 'cancelled') { cancelProvisioning(operation.id, 'Requester cancelled or replaced this operation'); return 'Requester cancelled this operation.'; }
        if (eligibility === 'held') return 'Waiting for the requester to resume.';
        return blocker(operation.server, operation.id, typed.action)?.message ?? null;
    }, options);
}

async function run(): Promise<void> {
    await processCreations();
    await processDestructions();
    await refreshRestartRollout();
    const operations = db().prepare(`SELECT id, server, action, state, stage FROM server_deployments
        WHERE server_deleted_at IS NULL AND action IN ('start','restart','stop','rebuild') AND (state = 'waiting' OR (action = 'stop' AND state = 'awaiting-health'))
        ORDER BY started_at, rowid`).all() as Operation[];
    for (const operation of operations) {
        if (nativeDeployment(operation.id)) continue;
        try { await processOperation(operation); }
        catch (err) {
            if (provisioningCancelled(operation.id)) continue;
            // Observation failures are retried; remote mutations are never replayed.
            deploymentStage(operation.id, 'Waiting for verification: ' + (err as Error).message, {
                checks: [], blocker: { code: 'observation-unavailable', message: (err as Error).message, automatic: true }
            });
        }
    }
}

async function processOperation(operation: Operation): Promise<void> {
    const { id, server, action } = operation;
    if (provisioningCancelled(id)) return;
    // An explicit cleanup resume follows confirmed remote deletion. Complete
    // that durable checkpoint even if the incident now needs attention or the
    // Watchdog is paused; never strand the reserved replacement identity.
    if (action === 'rebuild' && operation.stage === REMOVING_SERVER) { await rebuildServer(id); return; }
    if (operation.state === 'waiting') {
        const heldBy: Source[] = [];
        const eligibility = sourceEligibility(operation, source => heldBy.push(source));
        if (eligibility === 'cancelled') { cancelProvisioning(id, 'Requester cancelled or replaced this operation'); return; }
        if (eligibility === 'held') {
            const source = heldBy[0];
            const href = source ? source.kind === 'campaign' ? `/campaigns/${encodeURIComponent(source.source_id)}`
                : source.kind === 'beta' ? `/betas/${encodeURIComponent(source.source_id)}`
                : source.kind === 'watchdog' ? `/maintenance/${encodeURIComponent(source.source_id)}`
                : `/maintenance?view=activity#job-${encodeURIComponent(source.source_id)}` : null;
            deploymentStage(id, 'Waiting for the requester to resume', { phase: 'eligibility', checks: [],
                blocker: { code: 'requester-held', message: 'Waiting for the requester to resume', automatic: false, href, label: 'Requesting work' } });
            return;
        }
    }
    if (!getServer(server)) { finishDeployment(id, { ok: false, message: 'Server is no longer registered.' }); return; }
    const watchdog = sourcesFor(id).some(source => source.kind === 'watchdog');
    if (!komodoConfigured() || (!rconConfigured() && !watchdog)) { deploymentStage(id, 'Waiting for Komodo and RCON configuration', {
        phase: 'eligibility', checks: [], blocker: { code: 'configuration', message: 'Waiting for Komodo and RCON configuration', automatic: false, href: '/settings', label: 'Integration settings' }
    }); return; }
    if (operation.state === 'awaiting-health') {
        const health = await komodoInspectHealthy(server);
        if (!db().prepare("SELECT 1 FROM server_deployments WHERE id = ? AND server_deleted_at IS NULL AND state = 'awaiting-health'").get(id)) return;
        recordProgress(id, { phase: 'verify-stopped', checks: [{ key: 'stopped', label: 'Container stopped', source: 'komodo',
            result: isStopped(health.state) ? 'pass' : health.state ? 'waiting' : 'unknown', actual: health.state ?? null,
            message: health.ok ? null : health.reason }], blocker: isStopped(health.state) ? null
            : { code: 'stopped-state', message: 'Waiting for an explicit stopped container state.', automatic: true } });
        if (isStopped(health.state)) {
            db().transaction(() => {
                db().prepare("UPDATE servers SET container_state = ?, last_players = NULL, last_roster = NULL, game_started_at = NULL, game_ended_at = NULL WHERE name = ?").run(health.state, server);
                deploymentStage(id, 'Verified container stopped', { checkpoint: { key: 'verify-stopped', label: 'Stopped container state verified' } });
                finishDeployment(id, { ok: true });
            })();
        } else deploymentStage(id, 'Waiting for container to stop' + (!health.ok ? ': ' + health.reason : ''));
        return;
    }
    const reason = blocker(server, id, action);
    if (reason) { deploymentStage(id, reason.message, { phase: 'eligibility', checks: [], blocker: reason }); return; }
    const healthRecovery = watchdog && !!db().prepare(`SELECT 1 FROM provisioning_sources s
        JOIN watchdog_incidents i ON i.id = s.source_id JOIN server_deployments d ON d.id = s.operation_id
        WHERE s.operation_id = ? AND s.kind = 'watchdog' AND i.kind = 'health' AND d.triggered_by LIKE 'watchdog:%'`).get(id);
    const epoch = latestGameSubmission(server);
    const health = await komodoInspectHealthy(server);
    if (provisioningCancelled(id)) return;
    if (healthRecovery && epoch !== latestGameSubmission(server)) return;
    if (healthRecovery && !health.ok && !['stopped','exited','created','dead','unhealthy','starting','restarting'].includes(health.state?.toLowerCase() ?? '')) {
        deploymentStage(id, 'Waiting for current container health before automatic recovery', { phase: 'eligibility', checks: [],
            blocker: { code: 'observation-unavailable', message: health.reason, automatic: true } });
        return;
    }
    if (action !== 'start' && !isStopped(health.state)) {
        const evidence = await probePlayerEvidence(server);
        if (!db().prepare("SELECT 1 FROM server_deployments WHERE id = ? AND server_deleted_at IS NULL AND state = 'waiting'").get(id)) return;
        const players = evidence.players;
        if (healthRecovery && epoch !== latestGameSubmission(server)) return;
        if (healthRecovery && health.ok && players !== null) {
            // The fresh occupancy check also proves that the game recovered.
            // Empty is not a reason to execute an obsolete health restart.
            resolveRecoveredHealthOperation(id, players, evidence.source);
            return;
        }
        recordProgress(id, { phase: 'eligibility', checks: [{ key: 'occupancy', label: 'Player occupancy', result: players === 0 ? 'pass' : players === null ? 'unknown' : 'waiting',
            source: evidence.source, checkedAt: evidence.observedAt, receivedAt: evidence.receivedAt, expected: 0, actual: players }],
            blocker: players === 0 ? null : { code: players === null ? 'players-unknown' : 'players-present',
                message: players === null ? 'Waiting for a fresh player count' : `Waiting for ${players} player(s) to leave`, automatic: true } });
        db().prepare('UPDATE server_deployments SET players = ?, checked_at = ? WHERE id = ?').run(players, new Date().toISOString(), id);
        if (players !== 0) {
            deploymentStage(id, players === null ? 'Waiting for a fresh player count' : `Waiting for ${players} player(s) to leave`);
            return;
        }
    } else if (action !== 'start') {
        if (!db().prepare("SELECT 1 FROM server_deployments WHERE id = ? AND server_deleted_at IS NULL AND state = 'waiting'").get(id)) return;
        recordProgress(id, { phase: 'eligibility', blocker: null, checks: [{ key: 'stopped', label: 'Stopped container permits disruption',
            source: 'komodo', result: 'pass', actual: health.state ?? null }] });
    }
    // Requests can arrive during the probes. Recheck before claiming the action.
    const latestReason = blocker(server, id, action);
    if (latestReason) { deploymentStage(id, latestReason.message, { phase: 'eligibility', blocker: latestReason }); return; }
    if (sourceEligibility(operation) !== 'ready') return;
    if (!db().prepare("SELECT 1 FROM server_deployments WHERE id = ? AND server_deleted_at IS NULL AND state = 'waiting'").get(id)) return;
    if (action === 'rebuild') { await rebuildServer(id); return; }
    const claim = db().prepare("UPDATE server_deployments SET state = 'running' WHERE id = ? AND server_deleted_at IS NULL AND state = 'waiting'").run(id);
    if (!claim.changes) return;
    if (action === 'start' || action === 'restart') {
        const result = await restartInRollout(server, { operationId: id, action });
        if (provisioningCancelled(id)) return;
        if (result.kind === 'queued') {
            db().prepare("UPDATE server_deployments SET state = 'waiting' WHERE id = ?").run(id);
            deploymentStage(id, result.message);
        }
        return;
    }
    db().transaction(() => {
        db().prepare('UPDATE server_deployments SET submitted_at = ? WHERE id = ?').run(new Date().toISOString(), id);
        deploymentStage(id, 'Stopping container', { phase: 'container-action', blocker: null, checks: [],
            checkpoint: { key: 'eligibility', label: 'Eligibility checks passed' }, command: { state: 'attempted', message: 'Stop submission attempted.' } });
    })();
    // Persist intent first; a lost reply must not issue another stop later.
    try {
        const result = await komodoRuntimeAction(server, 'stop');
        if (provisioningCancelled(id)) return;
        if (!result.ok) {
            recordProgress(id, { command: { state: result.kind === 'no-name' || result.kind === 'unconfigured' ? 'rejected' : 'uncertain', message: result.message } });
            finishDeployment(id, { ok: false, message: result.message }); return;
        }
        db().transaction(() => {
            db().prepare("UPDATE server_deployments SET state = 'awaiting-health' WHERE id = ?").run(id);
            deploymentStage(id, 'Waiting for container to stop', { phase: 'verify-stopped',
                checkpoint: { key: 'container-action', label: 'Stop command accepted' },
                command: { state: 'accepted', message: 'Komodo accepted the stop request; stopped state still requires verification.' } });
        })();
    } catch (err) {
        if (provisioningCancelled(id)) return;
        recordProgress(id, { command: { state: 'uncertain', message: (err as Error).message } });
        finishDeployment(id, { ok: false, message: (err as Error).message });
    }
}