#!/usr/bin/env node
/**
 * IMAP IDLE Monitor for krillyclaw@gmail.com
 * Uses IMAP IDLE (RFC 2177) for real-time push notifications
 */

const path = require('path');
const https = require('https');

// Load imap modules (installed in this directory)
const Imap = require('imap');
const { simpleParser } = require('mailparser');

require('dotenv').config({ path: path.resolve(__dirname, '../.env.krillyclaw') });

const STATE_FILE = path.resolve(__dirname, '../../../workspace/memory/.krillyclaw-imap-state.json');
const GATEWAY_URL = 'http://127.0.0.1:18789/api/message/send';

let lastUid = 0;

function loadState() {
  try {
    const fs = require('fs');
    if (fs.existsSync(STATE_FILE)) {
      const state = JSON.parse(fs.readFileSync(STATE_FILE, 'utf8'));
      lastUid = state.last_uid || 0;
    }
  } catch (e) {
    console.error('Error loading state:', e.message);
  }
}

function saveState() {
  try {
    const fs = require('fs');
    fs.writeFileSync(STATE_FILE, JSON.stringify({ last_uid: lastUid, last_check: Date.now() }));
  } catch (e) {
    console.error('Error saving state:', e.message);
  }
}

function sendAlert(subject, from) {
  const message = `📬 **New email in krillyclaw@gmail.com**:\n\n• **${subject}**\n  From: ${from}\n\n— Krilly 🦀`;
  
  const data = JSON.stringify({
    channel: 'telegram',
    to: 'telegram:1793951355',
    message: message
  });
  
  const http = require('http');
  const req = http.request(GATEWAY_URL, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' }
  }, (res) => {
    console.log('Alert sent:', res.statusCode);
  });
  
  req.on('error', (e) => console.error('Alert failed:', e.message));
  req.write(data);
  req.end();
}

function createImap() {
  return new Imap({
    user: process.env.IMAP_USER,
    password: process.env.IMAP_PASS,
    host: process.env.IMAP_HOST,
    port: parseInt(process.env.IMAP_PORT),
    tls: process.env.IMAP_TLS === 'true',
    tlsOptions: { rejectUnauthorized: false },
    connTimeout: 60000,
    authTimeout: 10000
  });
}

function fetchNewMessages(imap, box) {
  return new Promise((resolve, reject) => {
    const searchCriteria = ['UNSEEN'];
    const fetchOptions = { bodies: ['HEADER.FIELDS (FROM SUBJECT)'], struct: true };
    
    imap.search(searchCriteria, (err, results) => {
      if (err) {
        reject(err);
        return;
      }
      
      if (!results || results.length === 0) {
        resolve([]);
        return;
      }
      
      const fetch = imap.fetch(results, fetchOptions);
      const messages = [];
      
      fetch.on('message', (msg, seqno) => {
        let header = {};
        let uid = 0;
        
        msg.on('body', (stream) => {
          let buffer = '';
          stream.on('data', (chunk) => buffer += chunk);
          stream.on('end', () => {
            header = Imap.parseHeader(buffer);
          });
        });
        
        msg.once('attributes', (attrs) => {
          uid = attrs.uid;
        });
        
        msg.once('end', () => {
          messages.push({
            uid,
            subject: header.subject ? header.subject[0] : 'No subject',
            from: header.from ? header.from[0] : 'Unknown'
          });
        });
      });
      
      fetch.once('error', reject);
      fetch.once('end', () => resolve(messages));
    });
  });
}

async function monitor() {
  loadState();
  console.log(`[${new Date().toISOString()}] Starting IMAP IDLE monitor for ${process.env.IMAP_USER}`);
  console.log(`[${new Date().toISOString()}] Last seen UID: ${lastUid}`);
  
  const imap = createImap();
  
  imap.once('ready', () => {
    imap.openBox('INBOX', false, async (err, box) => {
      if (err) {
        console.error('Error opening inbox:', err);
        return;
      }
      
      console.log(`[${new Date().toISOString()}] Connected to INBOX, watching for new emails...`);
      
      // Fetch initial unread messages
      try {
        const messages = await fetchNewMessages(imap, box);
        let newCount = 0;
        
        for (const msg of messages) {
          if (msg.uid > lastUid) {
            newCount++;
            lastUid = msg.uid;
            console.log(`[${new Date().toISOString()}] New message: ${msg.subject} (UID: ${msg.uid})`);
            sendAlert(msg.subject, msg.from);
          }
        }
        
        if (newCount > 0) {
          saveState();
        }
      } catch (e) {
        console.error('Error fetching messages:', e);
      }
      
      // Set up IDLE mode
      imap.on('mail', async (numNewMsgs) => {
        console.log(`[${new Date().toISOString()}] ${numNewMsgs} new message(s) received`);
        
        try {
          const messages = await fetchNewMessages(imap, box);
          
          for (const msg of messages) {
            if (msg.uid > lastUid) {
              lastUid = msg.uid;
              console.log(`[${new Date().toISOString()}] New message: ${msg.subject} (UID: ${msg.uid})`);
              sendAlert(msg.subject, msg.from);
              saveState();
            }
          }
        } catch (e) {
          console.error('Error fetching new messages:', e);
        }
      });
      
      imap.on('update', (seqno, info) => {
        console.log(`[${new Date().toISOString()}] Update: seqno=${seqno}`);
      });
      
      imap.on('expunge', (seqno) => {
        console.log(`[${new Date().toISOString()}] Expunge: seqno=${seqno}`);
      });
    });
  });
  
  imap.once('error', (err) => {
    console.error(`[${new Date().toISOString()}] IMAP error:`, err.message);
    // Reconnect after 30 seconds
    setTimeout(monitor, 30000);
  });
  
  imap.once('end', () => {
    console.log(`[${new Date().toISOString()}] Connection ended, reconnecting in 30s...`);
    setTimeout(monitor, 30000);
  });
  
  imap.connect();
}

// Handle graceful shutdown
process.on('SIGINT', () => {
  console.log('\nShutting down...');
  process.exit(0);
});

process.on('SIGTERM', () => {
  console.log('\nShutting down...');
  process.exit(0);
});

monitor();