const fs = require('fs');
const path = require('path');
const { TelegramClient } = require('telegram');
const { StringSession } = require('telegram/sessions');
const { Api } = require('telegram');
const TelegramBot = require('node-telegram-bot-api');
const { Logger } = require('telegram/extensions');
const input = require('input');

// Custom logger implementation
class CustomLogger {
  constructor(prefix) {
    this.prefix = prefix;
  }

  log(level, message) {
    // Implement your own logging if needed
    // console.log(`[${this.prefix}] ${level}: ${message}`);
  }

  error(message) {
    this.log('ERROR', message);
  }

  warn(message) {
    this.log('WARN', message);
  }

  info(message) {
    this.log('INFO', message);
  }

  debug(message) {
    this.log('DEBUG', message);
  }
}

// Bot token from environment
const BOT_TOKEN = process.env.BOT_TOKEN || '8019149324:AAGBAmRy0M-q6u0FqzREzwDtH-c5V-f9xoM';

// Create a new bot instance
const bot = new TelegramBot(BOT_TOKEN, { polling: true });

// Define conversation states
const STATES = {
  IDLE: 'idle',
  API_ID: 'api_id',
  API_HASH: 'api_hash',
  PHONE: 'phone',
  CODE: 'code',
  PASSWORD: 'password'
};

// Store user sessions and their current state
const userSessions = new Map();

// Validate phone number format
function isValidPhone(phone) {
  return /^\+\d{10,15}$/.test(phone);
}

// Create a clean session object for a user
function createUserSession(userId) {
  return {
    userId,
    state: STATES.IDLE,
    apiId: null,
    apiHash: null,
    phone: null,
    client: null,
    sessionName: `aayco_${userId}`,
    stringSession: null,
    phoneCodeHash: null
  };
}

// Clean up resources for a user session
async function cleanupSession(userId) {
  const session = userSessions.get(userId);
  if (!session) return;
  
  try {
    if (session.client) {
      await session.client.disconnect();
    }
    
    // Remove session file if it exists
    const sessionFile = `${session.sessionName}.session`;
    if (fs.existsSync(sessionFile)) {
      fs.unlinkSync(sessionFile);
    }
  } catch (error) {
    console.error(`Error cleaning up session for user ${userId}:`, error);
  } finally {
    userSessions.delete(userId);
  }
}

// Start command handler
bot.onText(/\/start/, async (msg) => {
  const userId = msg.from.id;
  await bot.sendMessage(userId, 
    "👋 Welcome to the Userbot Session Generator!\n\n" +
    "Use /pair to start creating your session file.\n" +
    "Use /cancel at any time to stop the process."
  );
});

// Pair command handler
bot.onText(/\/pair/, async (msg) => {
  const userId = msg.from.id;
  
  // Check if user already has an active session
  if (userSessions.has(userId)) {
    const existingSession = userSessions.get(userId);
    if (existingSession.state !== STATES.IDLE) {
      await bot.sendMessage(userId, 
        "⚠️ You already have an active session process.\n" +
        "Complete or /cancel it before starting a new one."
      );
      return;
    }
  }
  
  // Create new session for user
  const session = createUserSession(userId);
  session.state = STATES.API_ID;
  userSessions.set(userId, session);
  
  await bot.sendMessage(userId, 
    "🔐 Let's create your userbot session.\n" +
    "Please provide your **API ID** (a number from my.telegram.org):\n" +
    "Example: 1234567"
  );
});

// Cancel command handler
bot.onText(/\/cancel/, async (msg) => {
  const userId = msg.from.id;
  
  if (userSessions.has(userId)) {
    await cleanupSession(userId);
    await bot.sendMessage(userId, "🛑 Session creation cancelled.");
  } else {
    await bot.sendMessage(userId, "There's no active session to cancel.");
  }
});

// Handle all text messages
bot.on('message', async (msg) => {
  if (msg.text && msg.text.startsWith('/')) return;
  
  const userId = msg.from.id;
  const text = msg.text?.trim();
  
  if (!userSessions.has(userId) || !text) return;
  
  const session = userSessions.get(userId);
  
  try {
    switch (session.state) {
      case STATES.API_ID:
        await handleApiId(userId, text);
        break;
      case STATES.API_HASH:
        await handleApiHash(userId, text);
        break;
      case STATES.PHONE:
        await handlePhone(userId, text);
        break;
      case STATES.CODE:
        await handleCode(userId, text);
        break;
      case STATES.PASSWORD:
        await handlePassword(userId, text);
        break;
    }
  } catch (error) {
    console.error(`Error handling message for user ${userId}:`, error);
    await bot.sendMessage(userId, 
      `⚠️ An error occurred: ${error.message}\n` +
      "Please try again with /pair."
    );
    await cleanupSession(userId);
  }
});

// Process API ID input
async function handleApiId(userId, text) {
  if (!text.match(/^\d+$/)) {
    await bot.sendMessage(userId, 
      "❌ API ID must be a number.\n" +
      "Please send a valid **API ID**:"
    );
    return;
  }
  
  const session = userSessions.get(userId);
  session.apiId = parseInt(text, 10);
  session.state = STATES.API_HASH;
  
  await bot.sendMessage(userId, 
    "✅ API ID received.\n" +
    "Now provide your **API Hash** (a string from my.telegram.org):\n" +
    "Example: abcdef1234567890abcdef1234567890"
  );
}

// Process API Hash input
async function handleApiHash(userId, text) {
  if (text.length < 32) {
    await bot.sendMessage(userId, 
      "❌ API Hash must be at least 32 characters long.\n" +
      "Please send a valid **API Hash**:"
    );
    return;
  }
  
  const session = userSessions.get(userId);
  session.apiHash = text;
  session.state = STATES.PHONE;
  
  await bot.sendMessage(userId, 
    "✅ API Hash received.\n" +
    "Now provide your **phone number** (with country code):\n" +
    "Example: +12025550123"
  );
}

// Process phone number input
async function handlePhone(userId, phone) {
  if (!isValidPhone(phone)) {
    await bot.sendMessage(userId, 
      "❌ Invalid phone number format.\n" +
      "Please send a valid phone number (e.g., +12025550123):"
    );
    return;
  }
  
  const session = userSessions.get(userId);
  session.phone = phone;
  
  try {
    // Create a new StringSession
    const stringSession = new StringSession("");
    
    // Create a new TelegramClient with custom logger
    const client = new TelegramClient(
      stringSession,
      session.apiId,
      session.apiHash,
      {
        connectionRetries: 5,
        baseLogger: new CustomLogger('GramJS'),
        useWSS: false,
        autoReconnect: true
      }
    );
    
    session.client = client;
    
    // Connect and send code
    await client.connect();
    const result = await client.invoke(
      new Api.auth.SendCode({
        phoneNumber: session.phone,
        apiId: session.apiId,
        apiHash: session.apiHash,
        settings: new Api.CodeSettings({})
      })
    );
    
    session.phoneCodeHash = result.phoneCodeHash;
    session.state = STATES.CODE;
    
    await bot.sendMessage(userId, 
      "✅ Code request sent to your phone.\n" +
      "Please enter the verification code you received:"
    );
  } catch (error) {
    console.error('Error in handlePhone:', error);
    let errorMessage = error.message;
    
    if (error.errorMessage === 'PHONE_NUMBER_INVALID') {
      errorMessage = "The phone number is invalid. Please check and try again.";
    } else if (error.errorMessage === 'PHONE_NUMBER_BANNED') {
      errorMessage = "This phone number is banned from Telegram.";
    } else if (error.errorMessage.includes('FLOOD')) {
      errorMessage = "Too many attempts. Please wait before trying again.";
    }
    
    await bot.sendMessage(userId, 
      `❌ Error sending code: ${errorMessage}\n` +
      "Please try again with /pair or contact support."
    );
    await cleanupSession(userId);
  }
}

// Process verification code input
async function handleCode(userId, code) {
  if (!code.match(/^\d+$/)) {
    await bot.sendMessage(userId, 
      "❌ Code must be a number.\n" +
      "Please enter the verification code:"
    );
    return;
  }
  
  const session = userSessions.get(userId);
  
  try {
    // Sign in with the code
    const result = await session.client.invoke(
      new Api.auth.SignIn({
        phoneNumber: session.phone,
        phoneCodeHash: session.phoneCodeHash,
        phoneCode: code
      })
    );
    
    if (result._ === 'auth.authorizationSignUpRequired') {
      throw new Error("This phone number is not registered. Please sign up first.");
    }
    
    await finishSession(userId);
  } catch (error) {
    console.error('Error in handleCode:', error);
    
    if (error.errorMessage === "SESSION_PASSWORD_NEEDED") {
      session.state = STATES.PASSWORD;
      await bot.sendMessage(userId, 
        "🔒 Your account has two-factor authentication enabled.\n" +
        "Please enter your 2FA password:"
      );
    } else {
      let errorMessage = error.message;
      
      if (error.errorMessage === 'PHONE_CODE_INVALID') {
        errorMessage = "The verification code is invalid.";
      } else if (error.errorMessage === 'PHONE_CODE_EXPIRED') {
        errorMessage = "The verification code has expired. Please request a new one.";
      }
      
      await bot.sendMessage(userId, 
        `❌ Sign-in failed: ${errorMessage}\n` +
        "Please try again with /pair."
      );
      await cleanupSession(userId);
    }
  }
}

// Process 2FA password input
async function handlePassword(userId, password) {
  const session = userSessions.get(userId);
  
  try {
    // Sign in with 2FA password
    await session.client.invoke(
      new Api.auth.CheckPassword({
        password: password
      })
    );
    
    await finishSession(userId);
  } catch (error) {
    console.error('Error in handlePassword:', error);
    let errorMessage = error.message;
    
    if (error.errorMessage === 'PASSWORD_HASH_INVALID') {
      errorMessage = "The 2FA password is incorrect.";
    }
    
    await bot.sendMessage(userId, 
      `❌ 2FA authentication failed: ${errorMessage}\n` +
      "Please try again with /pair."
    );
    await cleanupSession(userId);
  }
}

// Complete the session creation and send the file
async function finishSession(userId) {
  const session = userSessions.get(userId);
  
  try {
    await bot.sendMessage(userId, 
      "🎉 Successfully signed in!\n" +
      "Generating your session file..."
    );
    
    const sessionString = session.client.session.save();
    const sessionFile = `aayco_${userId}.session`;
    fs.writeFileSync(sessionFile, sessionString);
    
    await bot.sendDocument(userId, sessionFile, {
      caption: "Here's your session file for your userbot. Keep it safe!",
      filename: 'aayco.session'
    });
    
    await cleanupSession(userId);
  } catch (error) {
    console.error('Error in finishSession:', error);
    await bot.sendMessage(userId, 
      `❌ Error creating session file: ${error.message}\n` +
      "Please try again with /pair."
    );
    await cleanupSession(userId);
  }
}

// Start the bot
console.log("Starting bot...");

// Error handling
bot.on('polling_error', (error) => {
  console.error('Polling error:', error);
});

process.on('unhandledRejection', (reason, promise) => {
  console.error('Unhandled Rejection at:', promise, 'reason:', reason);
});

// Graceful shutdown
process.on('SIGINT', async () => {
  console.log('Shutting down...');
  
  for (const [userId, session] of userSessions.entries()) {
    try {
      await cleanupSession(userId);
    } catch (error) {
      console.error(`Error cleaning up session for user ${userId}:`, error);
    }
  }
  
  bot.stopPolling();
  process.exit(0);
});