/**
 * GoldRate Engine — Telegram Bot for API Key Management
 * 
 * Private admin bot to create, list, revoke, and check API keys.
 * Only authorized admin Telegram IDs can use this bot.
 * 
 * Commands:
 *   /start          — Welcome message
 *   /create_sln     — Create SLN (Chennai) API key
 *   /create_ibja    — Create IBJA (India) API key
 *   /list           — List all active keys
 *   /revoke         — Revoke a key
 *   /check          — Check key status
 *   /help           — Show all commands
 * 
 * Setup:
 *   1. Create a bot via @BotFather on Telegram
 *   2. Add TELEGRAM_BOT_TOKEN to .env
 *   3. Add your Telegram user ID to TELEGRAM_ADMIN_IDS in .env
 *   4. Start: node src/telegramBot.js (or auto-starts with server)
 */

require('dotenv').config();
const TelegramBotModule = require('node-telegram-bot-api');
const TelegramBot = TelegramBotModule.default || TelegramBotModule;
const crypto = require('crypto');
const { createClient } = require('@supabase/supabase-js');

// ── Config ───────────────────────────────────────────
const BOT_TOKEN = process.env.TELEGRAM_BOT_TOKEN;
const ADMIN_IDS = (process.env.TELEGRAM_ADMIN_IDS || '')
  .split(',')
  .map(id => id.trim())
  .filter(Boolean);

let supabase = null;
let bot = null;

// ── Initialize ───────────────────────────────────────
function initTelegramBot() {
  if (!BOT_TOKEN) {
    console.log('ℹ️  TELEGRAM_BOT_TOKEN not set — Telegram bot disabled');
    return null;
  }

  const supabaseUrl = process.env.SUPABASE_URL;
  const supabaseKey = process.env.SUPABASE_SERVICE_ROLE_KEY;

  if (!supabaseUrl || !supabaseKey) {
    console.log('⚠️  Supabase not configured — Telegram bot disabled');
    return null;
  }

  supabase = createClient(supabaseUrl, supabaseKey);
  bot = new TelegramBot(BOT_TOKEN, { polling: true });

  // Global error handler — prevent crashes
  bot.on('polling_error', (err) => {
    console.warn('⚠️ Telegram polling error:', err.message);
  });

  bot.on('error', (err) => {
    console.warn('⚠️ Telegram error:', err.message);
  });

  // Register handlers
  bot.onText(/\/start/, safeHandler(handleStart));
  bot.onText(/\/help/, safeHandler(handleHelp));
  bot.onText(/\/create_sln(.*)/, safeHandler(handleCreateSLN));
  bot.onText(/\/create_ibja(.*)/, safeHandler(handleCreateIBJA));
  bot.onText(/\/list/, safeHandler(handleList));
  bot.onText(/\/revoke(.*)/, safeHandler(handleRevoke));
  bot.onText(/\/check(.*)/, safeHandler(handleCheck));

  console.log('🤖 Telegram Bot started! Waiting for commands...');
  
  if (ADMIN_IDS.length > 0) {
    console.log(`🔒 Authorized admins: ${ADMIN_IDS.join(', ')}`);
  } else {
    console.log('⚠️  No TELEGRAM_ADMIN_IDS set — bot will tell you your ID on /start');
  }

  return bot;
}

// ── Safe handler wrapper (prevents crashes) ──────────
function safeHandler(fn) {
  return async (msg, match) => {
    try {
      await fn(msg, match);
    } catch (err) {
      console.error('⚠️ Telegram handler error:', err.message);
      try {
        await bot.sendMessage(msg.chat.id, `❌ Error: ${err.message}`);
      } catch (e) {
        console.error('⚠️ Could not send error message:', e.message);
      }
    }
  };
}

// ── Auth Check ───────────────────────────────────────
function isAdmin(chatId) {
  if (ADMIN_IDS.length === 0) return true;
  return ADMIN_IDS.includes(chatId.toString());
}

function generateApiKey(source) {
  const prefix = source.toLowerCase();
  const random = crypto.randomBytes(16).toString('hex');
  return `${prefix}_${random}`;
}

// ── HTML helper ──────────────────────────────────────
function esc(text) {
  return String(text).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
}

// ── /start ───────────────────────────────────────────
async function handleStart(msg) {
  const chatId = msg.chat.id;
  const name = esc(msg.from.first_name || 'Admin');

  const adminStatus = isAdmin(chatId) 
    ? '✅ You are authorized as admin' 
    : '❌ Not authorized. Add your ID to TELEGRAM_ADMIN_IDS in .env';

  const text = 
`🪙 <b>GoldRate Engine — API Key Bot</b>

Welcome ${name}! 👋

Your Telegram ID: <code>${chatId}</code>
${adminStatus}

<b>Available Commands:</b>
/create_sln <code>Owner Name</code> — Chennai (SLN) key
/create_ibja <code>Owner Name</code> — India (IBJA) key
/list — List all API keys
/check <code>api_key</code> — Check key details
/revoke <code>api_key</code> — Deactivate a key
/help — Show this message`;

  await bot.sendMessage(chatId, text, { parse_mode: 'HTML' });
}

// ── /help ────────────────────────────────────────────
async function handleHelp(msg) {
  return handleStart(msg);
}

// ── /create_sln ──────────────────────────────────────
async function handleCreateSLN(msg, match) {
  const chatId = msg.chat.id;
  if (!isAdmin(chatId)) {
    return bot.sendMessage(chatId, '❌ Unauthorized. Contact admin.');
  }

  const args = (match[1] || '').trim();
  if (!args) {
    return bot.sendMessage(chatId, 
      '⚠️ Usage: /create_sln <code>Owner Name [Days]</code>\n\nExample: /create_sln Gold Shop ABC 90', 
      { parse_mode: 'HTML' });
  }

  // Parse name and optional days (e.g. "Shop Name 90" -> "Shop Name" and 90 days)
  const parts = args.split(/\s+/);
  let days = 30;
  let ownerName = args;

  if (parts.length > 1) {
    const lastPart = parts[parts.length - 1];
    if (/^\d+$/.test(lastPart)) {
      days = parseInt(lastPart);
      ownerName = parts.slice(0, -1).join(' ');
    }
  }

  await createKey(chatId, ownerName, 'SLN', days);
}

// ── /create_ibja ─────────────────────────────────────
async function handleCreateIBJA(msg, match) {
  const chatId = msg.chat.id;
  if (!isAdmin(chatId)) {
    return bot.sendMessage(chatId, '❌ Unauthorized. Contact admin.');
  }

  const args = (match[1] || '').trim();
  if (!args) {
    return bot.sendMessage(chatId, 
      '⚠️ Usage: /create_ibja <code>Owner Name [Days]</code>\n\nExample: /create_ibja Jeweller XYZ 120', 
      { parse_mode: 'HTML' });
  }

  // Parse name and optional days
  const parts = args.split(/\s+/);
  let days = 30;
  let ownerName = args;

  if (parts.length > 1) {
    const lastPart = parts[parts.length - 1];
    if (/^\d+$/.test(lastPart)) {
      days = parseInt(lastPart);
      ownerName = parts.slice(0, -1).join(' ');
    }
  }

  await createKey(chatId, ownerName, 'IBJA', days);
}

// ── Create Key (shared) ─────────────────────────────
async function createKey(chatId, ownerName, source, days = 30) {
  const apiKey = generateApiKey(source);
  const expiresAt = new Date();
  expiresAt.setDate(expiresAt.getDate() + days);

  const { data, error } = await supabase
    .from('api_keys')
    .insert({
      api_key: apiKey,
      owner_name: ownerName,
      source: source,
      expires_at: expiresAt.toISOString(),
      is_active: true,
      notes: `Created via Telegram by ${chatId}`
    })
    .select()
    .single();

  if (error) {
    return bot.sendMessage(chatId, 
      `❌ Failed to create key: ${esc(error.message)}\n\n💡 Did you create the <code>api_keys</code> table in Supabase?`, 
      { parse_mode: 'HTML' });
  }

  const expiryStr = expiresAt.toLocaleDateString('en-IN', { 
    day: '2-digit', month: 'short', year: 'numeric' 
  });

  const sourceName = source === 'SLN' ? 'SLN Bullion Chennai' : 'IBJA India';

  const text = 
`✅ <b>API Key Created!</b>

🔑 <b>Key:</b>
<code>${apiKey}</code>

👤 <b>Owner:</b> ${esc(ownerName)}
📍 <b>Source:</b> ${sourceName}
📅 <b>Valid Until:</b> ${expiryStr}
⏱ <b>Duration:</b> ${days} days

Copy the key above and share with the user.`;

  await bot.sendMessage(chatId, text, { parse_mode: 'HTML' });
}

// ── /list ────────────────────────────────────────────
async function handleList(msg) {
  const chatId = msg.chat.id;
  if (!isAdmin(chatId)) {
    return bot.sendMessage(chatId, '❌ Unauthorized.');
  }

  const { data, error } = await supabase
    .from('api_keys')
    .select('*')
    .order('created_at', { ascending: false })
    .limit(20);

  if (error) {
    return bot.sendMessage(chatId, `❌ Error: ${esc(error.message)}`);
  }

  if (!data || data.length === 0) {
    return bot.sendMessage(chatId, 
      '📋 No API keys found.\n\nCreate one with /create_sln or /create_ibja');
  }

  const now = new Date();
  let text = `📋 <b>API Keys (${data.length})</b>\n\n`;

  for (const key of data) {
    const expired = new Date(key.expires_at) < now;
    const status = !key.is_active ? '❌ Revoked' : expired ? '⏰ Expired' : '✅ Active';
    const daysLeft = Math.max(0, Math.ceil((new Date(key.expires_at) - now) / (1000 * 60 * 60 * 24)));
    const expiryStr = new Date(key.expires_at).toLocaleDateString('en-IN', { day: '2-digit', month: 'short' });

    text += `${status} <b>${esc(key.owner_name)}</b> (${key.source})\n`;
    text += `<code>${key.api_key.substring(0, 20)}...</code>\n`;
    text += `Expires: ${expiryStr}${!expired && key.is_active ? ` (${daysLeft}d left)` : ''}\n\n`;
  }

  text += 'Use /check <code>KEY</code> to see full details';
  await bot.sendMessage(chatId, text, { parse_mode: 'HTML' });
}

// ── /revoke ──────────────────────────────────────────
async function handleRevoke(msg, match) {
  const chatId = msg.chat.id;
  if (!isAdmin(chatId)) {
    return bot.sendMessage(chatId, '❌ Unauthorized.');
  }

  const apiKey = (match[1] || '').trim();
  if (!apiKey) {
    return bot.sendMessage(chatId, '⚠️ Usage: /revoke <code>api_key_here</code>', { parse_mode: 'HTML' });
  }

  const { data, error } = await supabase
    .from('api_keys')
    .update({ is_active: false })
    .eq('api_key', apiKey)
    .select()
    .single();

  if (error || !data) {
    return bot.sendMessage(chatId, `❌ Key not found: <code>${esc(apiKey)}</code>`, { parse_mode: 'HTML' });
  }

  await bot.sendMessage(chatId, 
    `✅ <b>Key Revoked</b>\n\n👤 Owner: ${esc(data.owner_name)}\n📍 Source: ${data.source}\n🔑 Key: <code>${esc(apiKey)}</code>`, 
    { parse_mode: 'HTML' });
}

// ── /check ───────────────────────────────────────────
async function handleCheck(msg, match) {
  const chatId = msg.chat.id;
  if (!isAdmin(chatId)) {
    return bot.sendMessage(chatId, '❌ Unauthorized.');
  }

  const apiKey = (match[1] || '').trim();
  if (!apiKey) {
    return bot.sendMessage(chatId, '⚠️ Usage: /check <code>api_key_here</code>', { parse_mode: 'HTML' });
  }

  const { data, error } = await supabase
    .from('api_keys')
    .select('*')
    .eq('api_key', apiKey)
    .single();

  if (error || !data) {
    return bot.sendMessage(chatId, `❌ Key not found: <code>${esc(apiKey)}</code>`, { parse_mode: 'HTML' });
  }

  const now = new Date();
  const expired = new Date(data.expires_at) < now;
  const daysLeft = Math.max(0, Math.ceil((new Date(data.expires_at) - now) / (1000 * 60 * 60 * 24)));
  const status = !data.is_active ? '❌ Revoked' : expired ? '⏰ Expired' : '✅ Active';
  const createdStr = new Date(data.created_at).toLocaleDateString('en-IN', { day: '2-digit', month: 'short', year: 'numeric' });
  const expiryStr = new Date(data.expires_at).toLocaleDateString('en-IN', { day: '2-digit', month: 'short', year: 'numeric' });
  const sourceName = data.source === 'SLN' ? '📍 SLN Bullion Chennai' : '🇮🇳 IBJA India';
  const daysInfo = (!expired && data.is_active) ? `\n<b>Days Left:</b> ${daysLeft}` : '';

  const text = 
`🔑 <b>API Key Details</b>

<b>Key:</b> <code>${data.api_key}</code>
<b>Owner:</b> ${esc(data.owner_name)}
<b>Phone:</b> ${data.owner_phone || 'N/A'}
<b>Email:</b> ${data.owner_email || 'N/A'}
<b>Source:</b> ${sourceName}
<b>Status:</b> ${status}
<b>Created:</b> ${createdStr}
<b>Expires:</b> ${expiryStr}${daysInfo}`;

  await bot.sendMessage(chatId, text, { parse_mode: 'HTML' });
}

// ── Export ────────────────────────────────────────────
module.exports = { initTelegramBot };

// ── Run standalone ───────────────────────────────────
if (require.main === module) {
  console.log('🤖 Starting Telegram Bot standalone...');
  const botInstance = initTelegramBot();
  if (!botInstance) {
    console.error('❌ Bot could not start. Check TELEGRAM_BOT_TOKEN in .env');
    process.exit(1);
  }
}