const express = require('express');
const bodyParser = require('body-parser');
const axios = require('axios');
const fs = require('fs');
const path = require('path');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 3001;

// Middleware
app.use(bodyParser.json());

// Chatwoot API helper
const chatwootAPI = axios.create({
  baseURL: process.env.CHATWOOT_URL,
  headers: {
    'api_token': process.env.CHATWOOT_API_TOKEN,
    'Content-Type': 'application/json'
  }
});

// Load FAQ/Knowledge Base
function loadKnowledgeBase() {
  const kbPath = path.join(__dirname, '../FAQ-KB.md');
  if (fs.existsSync(kbPath)) {
    return fs.readFileSync(kbPath, 'utf8');
  }
  return '';
}

// Simple keyword-based intent detection
function detectIntent(message) {
  const lower = message.toLowerCase();
  
  if (lower.includes('price') || lower.includes('cost') || lower.includes('billing') || lower.includes('payment')) {
    return { intent: 'billing', confidence: 0.8 };
  }
  
  if (lower.includes('bug') || lower.includes('error') || lower.includes('not working') || lower.includes('issue')) {
    return { intent: 'technical_issue', confidence: 0.85 };
  }
  
  if (lower.includes('how to') || lower.includes('feature') || lower.includes('use')) {
    return { intent: 'feature_request', confidence: 0.75 };
  }
  
  if (lower.includes('account') || lower.includes('login') || lower.includes('password')) {
    return { intent: 'account', confidence: 0.8 };
  }
  
  if (lower.includes('hello') || lower.includes('hi') || lower.includes('help')) {
    return { intent: 'greeting', confidence: 0.9 };
  }
  
  return { intent: 'unknown', confidence: 0.5 };
}

// Search knowledge base for answer
function searchKnowledgeBase(question) {
  const kb = loadKnowledgeBase();
  const keywords = question.toLowerCase().split(' ').filter(w => w.length > 3);
  
  // Simple keyword matching - can be enhanced with embeddings later
  const sections = kb.split('## ');
  for (const section of sections) {
    const score = keywords.filter(k => section.toLowerCase().includes(k)).length;
    if (score >= 2) {
      return section.trim();
    }
  }
  
  return null;
}

// Send message to Chatwoot conversation
async function sendMessage(conversationId, content) {
  try {
    await chatwootAPI.post(`/api/v1/accounts/${process.env.CHATWOOT_ACCOUNT_ID}/conversations/${conversationId}/messages`, {
      content: content,
      message_type: 'outgoing'
    });
    console.log(`Sent message to conversation ${conversationId}`);
  } catch (error) {
    console.error('Error sending message:', error.response?.data || error.message);
  }
}

// Escalate conversation to human agent
async function escalateToHuman(conversationId, contactName, reason) {
  try {
    // Change status to 'open' to assign to human agent
    await chatwootAPI.patch(`/api/v1/accounts/${process.env.CHATWOOT_ACCOUNT_ID}/conversations/${conversationId}`, {
      status: 'open'
    });
    
    console.log(`Escalated conversation ${conversationId} to human`);
    
    // Send Telegram notification
    await sendTelegramNotification(contactName, reason, conversationId);
  } catch (error) {
    console.error('Error escalating:', error.response?.data || error.message);
  }
}

// Send Telegram notification on escalation
async function sendTelegramNotification(contactName, reason, conversationId) {
  if (!process.env.TELEGRAM_BOT_TOKEN || !process.env.TELEGRAM_CHAT_ID) {
    console.log('Telegram not configured, skipping notification');
    return;
  }
  
  const message = `🔔 *Support Escalation*\n\n` +
    `*Customer:* ${contactName}\n` +
    `*Reason:* ${reason}\n` +
    `*Conversation:* ${conversationId}\n\n` +
    `Jump in: ${process.env.CHATWOOT_URL}/app/accounts/${process.env.CHATWOOT_ACCOUNT_ID}/conversations/${conversationId}`;
  
  try {
    await axios.post(
      `https://api.telegram.org/bot${process.env.TELEGRAM_BOT_TOKEN}/sendMessage`,
      {
        chat_id: process.env.TELEGRAM_CHAT_ID,
        text: message,
        parse_mode: 'Markdown'
      }
    );
    console.log('Telegram notification sent');
  } catch (error) {
    console.error('Error sending Telegram:', error.message);
  }
}

// Handle incoming webhook from Chatwoot
app.post('/webhook', async (req, res) => {
  const event = req.body;
  console.log('Received webhook:', event.event);
  
  // Only process message_created events
  if (event.event !== 'message_created') {
    return res.status(200).send('OK');
  }
  
  const { conversation, message } = event.data;
  
  // Ignore outgoing messages (from agents/bots)
  if (message.message_type !== 'incoming') {
    return res.status(200).send('OK');
  }
  
  const conversationId = conversation.id;
  const contactName = conversation.meta?.sender?.name || 'Unknown';
  const userMessage = message.content;
  
  console.log(`Message from ${contactName}: ${userMessage}`);
  
  // Detect intent
  const { intent, confidence } = detectIntent(userMessage);
  console.log(`Intent: ${intent} (${confidence})`);
  
  // Handle based on intent
  if (intent === 'greeting') {
    await sendMessage(conversationId, 
      `Hi ${contactName}! 👋 Welcome to HOA Ledger IQ support. \n\n` +
      `I'm here to help you get started. Could you tell me a bit about what you're looking to accomplish?\n\n` +
      `If you need immediate assistance from our team, just let me know!`
    );
  } 
  else if (intent === 'billing' || intent === 'account' || intent === 'feature_request') {
    // Try to find answer in knowledge base
    const answer = searchKnowledgeBase(userMessage);
    
    if (answer) {
      await sendMessage(conversationId, 
        `Thanks for your question! Here's what I found:\n\n${answer}\n\n` +
        `Does this answer your question? If you need more help, I can connect you with Chris.`
      );
    } else {
      // No KB answer - escalate
      await sendMessage(conversationId, 
        `Great question! Let me get Chris to help you with this. One moment! 👍`
      );
      await escalateToHuman(conversationId, contactName, `${intent} - no KB answer`);
    }
  }
  else if (intent === 'technical_issue') {
    // Technical issues usually need human attention
    await sendMessage(conversationId, 
      `I understand you're experiencing an issue. Let me get Chris to help you troubleshoot this. \n\n` +
      `In the meantime, could you share:\n` +
      `• What browser/device you're using?\n` +
      `• Any error messages you're seeing?\n` +
      `• Steps to reproduce the issue?`
    );
    await escalateToHuman(conversationId, contactName, `technical_issue`);
  }
  else {
    // Unknown intent - ask for clarification or escalate
    await sendMessage(conversationId, 
      `Thanks for reaching out! To make sure I direct you to the right place, could you tell me a bit more about what you need help with?\n\n` +
      `• Billing or pricing questions\n` +
      `• Feature questions\n` +
      `• Technical issues\n` +
      `• Account access\n\n` +
      `Or I can connect you directly with Chris if you prefer!`
    );
  }
  
  res.status(200).send('OK');
});

// Health check endpoint
app.get('/health', (req, res) => {
  res.json({ status: 'ok', timestamp: new Date().toISOString() });
});

// Start server
app.listen(PORT, () => {
  console.log(`🤖 Chatwoot Agent Bot running on port ${PORT}`);
  console.log(`Webhook endpoint: http://localhost:${PORT}/webhook`);
  console.log(`Health check: http://localhost:${PORT}/health`);
});