'use strict';

const cron = require('node-cron');
const database = require('../config/database');
const {
  syncFollowUpMonitorDailySnapshot,
  DEFAULT_REQUEST_TIMEOUT_MS,
} = require('../services/followUpMonitorSync');

let running = false;
const JOB_LOCK_WAIT_SECONDS = Math.max(parseInt(process.env.FOLLOW_UP_MONITOR_LOCK_WAIT_SECONDS || '1', 10), 0);
const JOB_ENABLED = String(process.env.FOLLOW_UP_MONITOR_ENABLED || 'true').toLowerCase() !== 'false';
const JOB_CRON = process.env.FOLLOW_UP_MONITOR_CRON || '20 6 * * *';

async function withGlobalJobLock(lockKey, trigger, runner) {
  const connection = await database.local.pool.getConnection();
  let lockAcquired = false;

  try {
    const [rows] = await connection.query('SELECT GET_LOCK(?, ?) AS lockStatus', [ lockKey, JOB_LOCK_WAIT_SECONDS ]);
    const lockStatus = rows && rows[0] ? Number(rows[0].lockStatus) : 0;
    lockAcquired = lockStatus === 1;

    if (!lockAcquired) {
      console.log(`[FollowUpMonitor] global lock not acquired, skip trigger=${trigger}, lockKey=${lockKey}`);
      return { success: false, skipped: true, reason: 'global_lock_not_acquired', trigger, lockKey };
    }

    return runner();
  } finally {
    try {
      if (lockAcquired) {
        await connection.query('DO RELEASE_LOCK(?)', [ lockKey ]);
      }
    } finally {
      connection.release();
    }
  }
}

async function runFollowUpMonitorJob(trigger = 'manual', options = {}) {
  if (running) {
    console.log(`[FollowUpMonitor] job is already running, skip trigger=${trigger}`);
    return { success: false, skipped: true, reason: 'running', trigger };
  }

  running = true;
  try {
    return await withGlobalJobLock('follow_up_monitor_daily', trigger, async () => {
      const result = await syncFollowUpMonitorDailySnapshot({
        targetDate: options.targetDate || null,
        goodsIds: Array.isArray(options.goodsIds) ? options.goodsIds : null,
        requestTimeout: options.requestTimeout || DEFAULT_REQUEST_TIMEOUT_MS,
      });
      return { ...result, trigger };
    });
  } finally {
    running = false;
  }
}

function startFollowUpMonitorSchedulers() {
  if (!JOB_ENABLED) {
    console.log('[Scheduler] 跟进监控日任务未启用');
    return;
  }

  cron.schedule(JOB_CRON, () => {
    runFollowUpMonitorJob('daily_schedule').catch((error) => {
      console.error('[FollowUpMonitor] scheduled job failed', error);
    });
  }, { timezone: 'Asia/Shanghai' });

  console.log(`[Scheduler] 跟进监控日任务已注册: ${JOB_CRON} (Asia/Shanghai)`);
}

module.exports = {
  startFollowUpMonitorSchedulers,
  runFollowUpMonitorJob,
};