const os = require('os');
const { openRuntimeDb } = require('../src/db/runtime');
const { initAutonomySchema } = require('../src/autonomy/schema');
const { enqueueJob, leaseNextJob, completeJob, failJob } = require('../src/autonomy/jobs');

function sleep(ms) { return new Promise((resolve) => setTimeout(resolve, ms)); }

function isTransientCoordinatorFailure(error) {
  const value = String(error || '').toLowerCase();
  return value.includes('fetch failed')
    || value.includes('network')
    || value.includes('timeout')
    || value.includes('before response')
    || /\b(408|429|5\d\d)\b/.test(value);
}

function enqueueCoordinatorEvent(intelligenceDb, row) {
  const isLive = row.ingested_at && Date.now() - Date.parse(row.ingested_at) <= 48 * 60 * 60 * 1000;
  const lane = isLive ? 'live' : 'historical';
  const priority = isLive ? 100 : 10;
  const idempotencyKey = `coordinator_event:${row.event_id}`;
  const result = enqueueJob(intelligenceDb, {
    jobType: 'coordinator_event',
    lane,
    priority,
    entityType: 'event',
    entityId: row.event_id,
    idempotencyKey,
  });
  if (result.inserted) return { inserted: true, recovered: false };

  const existing = intelligenceDb.prepare(`
    SELECT id, status, last_error
    FROM autonomy_jobs
    WHERE idempotency_key = ? AND job_type = 'coordinator_event'
  `).get(idempotencyKey);
  if (!existing || existing.status !== 'dead_letter' || !isTransientCoordinatorFailure(existing.last_error)) {
    return { inserted: false, recovered: false };
  }

  const recovered = intelligenceDb.prepare(`
    UPDATE autonomy_jobs
    SET status = 'pending',
        lane = ?,
        priority = ?,
        attempts = 0,
        available_at = datetime('now'),
        leased_by = NULL,
        lease_expires_at = NULL,
        last_error = ?
    WHERE id = ? AND status = 'dead_letter'
  `).run(lane, priority, `Recovered transient coordinator failure: ${existing.last_error || 'unknown error'}`, existing.id);
  return { inserted: false, recovered: recovered.changes > 0 };
}

function reconcileArchiveBatch(archiveDb, intelligenceDb, batchSize = 250) {
  const cursor = intelligenceDb.prepare("SELECT value FROM autonomy_cursors WHERE key = 'archive_reconcile'").get();
  const afterId = cursor ? cursor.value : 0;
  const rows = archiveDb.prepare(`
    SELECT id, event_id, ingested_at, content, has_embedding
    FROM articles
    WHERE id > ?
    ORDER BY id ASC
    LIMIT ?
  `).all(afterId, batchSize);
  if (!rows.length) {
    intelligenceDb.prepare(`
      INSERT INTO autonomy_cursors(key, value) VALUES ('archive_reconcile', 0)
      ON CONFLICT(key) DO UPDATE SET value = 0, updated_at = datetime('now')
    `).run();
    return { scanned: 0, nextCursor: 0, reset: true };
  }
  const enqueue = intelligenceDb.transaction(() => {
    for (const row of rows) {
      const readyForIntelligence = row.event_id && row.content && row.has_embedding;
      if (readyForIntelligence) {
        enqueueCoordinatorEvent(intelligenceDb, row);
      }
    }
    intelligenceDb.prepare(`
      INSERT INTO autonomy_cursors(key, value) VALUES ('archive_reconcile', ?)
      ON CONFLICT(key) DO UPDATE SET value = excluded.value, updated_at = datetime('now')
    `).run(rows[rows.length - 1].id);
  });
  enqueue();
  return { scanned: rows.length, nextCursor: rows[rows.length - 1].id, reset: false };
}

function reconcileLiveBatch(archiveDb, intelligenceDb, batchSize = 250) {
  const rows = archiveDb.prepare(`
    SELECT id, event_id, ingested_at, content, has_embedding
    FROM articles
    WHERE ingested_at >= datetime('now', '-48 hours')
    ORDER BY ingested_at DESC, id DESC
    LIMIT ?
  `).all(batchSize);
  let queued = 0;
  for (const row of rows) {
    if (!row.event_id || !row.content || !row.has_embedding) continue;
    const result = enqueueCoordinatorEvent(intelligenceDb, row);
    if (result.inserted || result.recovered) queued++;
  }
  return { scanned: rows.length, queued };
}

async function runAutonomyWorker({ archivePath, intelligencePath, workerId = `autonomy-${os.hostname()}-${process.pid}`, pollMs = 1000 } = {}) {
  const archiveDb = openRuntimeDb(archivePath, { schema: 'archive', readonly: true });
  const intelligenceDb = openRuntimeDb(intelligencePath, { schema: 'intelligence' });
  intelligenceDb.pragma('journal_mode = WAL');
  intelligenceDb.pragma('busy_timeout = 5000');
  initAutonomySchema(intelligenceDb);

  while (true) {
    // This worker owns maintenance reconciliation only. Without the type filter it
    // can lease coordinator_event jobs and complete them without analysis.
    const job = leaseNextJob(intelligenceDb, workerId, 120, ['reconcile_archive']);
    if (!job) { await sleep(pollMs); continue; }
    try {
      if (job.job_type === 'reconcile_archive') {
        reconcileLiveBatch(archiveDb, intelligenceDb);
        reconcileArchiveBatch(archiveDb, intelligenceDb);
        // Keep the reconciler alive as a bounded maintenance loop.
        enqueueJob(intelligenceDb, {
          jobType: 'reconcile_archive', lane: 'maintenance', priority: 100,
          entityType: 'archive', entityId: 'archive',
          idempotencyKey: `reconcile_archive:${Date.now()}`,
        });
      }
      completeJob(intelligenceDb, job.id, workerId);
    } catch (error) {
      failJob(intelligenceDb, job.id, workerId, error);
    }
    await sleep(pollMs);
  }
}

module.exports = { enqueueCoordinatorEvent, reconcileArchiveBatch, reconcileLiveBatch, runAutonomyWorker };