cronJobs.js

const cron = require('node-cron');
const { fetchAndStoreNews, deleteAllNews, pool } = require('./newsFetcher');

// Flags to prevent overlapping jobs
let isDailyResetRunning = false;
let isThreeHourlyRunning = false;

// Retry helper with exponential backoff
async function retry(fn, retries = 3, delay = 2000) {
  for (let i = 0; i < retries; i++) {
    try {
        return await fn();
    } catch (err) {
        console.error(`[${new Date().toISOString()}] Attempt ${i + 1} failed:`, err.message);
        if (i < retries - 1) {
            await new Promise(r => setTimeout(r, delay * (i + 1)));
        } else {
            throw err;
        }
    }
  }
}

// Safe wrapper with logging
async function safeRun(jobName, fn) {
  try {
    console.log(`[${new Date().toISOString()}] Starting job: ${jobName}`);
    await fn();
    console.log(`[${new Date().toISOString()}] Completed job: ${jobName}`);
  } catch (err) {
    console.error(`[${new Date().toISOString()}] Error in job: ${jobName}`, err);
  }
}

// Daily reset at 2 AM
cron.schedule('0 2 * * *', async () => {
  if (isDailyResetRunning) {
    console.warn(`[${new Date().toISOString()}] Daily reset already running, skipping`);
    return;
  }
  isDailyResetRunning = true;

  await safeRun('Daily Reset + Fetch', async () => {
    const client = await pool.connect();
    try {
        // Begin transaction
        await client.query('BEGIN');
        await deleteAllNews(client);
        await fetchAndStoreNews(client);
        // Commit transaction if everything succeeds
        await client.query('COMMIT');
    } catch (err) {
        // RollBack if transaction fails
        await client.query('ROLLBACK');
        console.error(`[${new Date().toISOString()}] Transaction rolled back due to error`);
        throw err;
    } finally {
        client.release();
    }
  });

  isDailyResetRunning = false;
});

// 3-hourly incremental fetch
cron.schedule('0 */3 * * *', async () => {
  if (isThreeHourlyRunning || isDailyResetRunning) {
    console.warn(`[${new Date().toISOString()}] 3-hourly fetch skipped due to overlap`);
    return;
  }
  isThreeHourlyRunning = true;

  await safeRun('3-Hourly Fetch', async () => {
    await retry(fetchAndStoreNews, 3);
  });

  isThreeHourlyRunning = false;
});

console.log(`[${new Date().toISOString()}] Cron jobs scheduled...`);