import express from 'express';
import path from 'path';
import { fileURLToPath } from 'url';
import mysql from 'mysql2/promise';
import cors from 'cors';
import dotenv from 'dotenv';

dotenv.config();

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const app = express();
const PORT = process.env.PORT || 3000;

app.use(cors());
app.use(express.json());
app.use(express.static(path.join(__dirname, 'dist')));

// DB Configuration for internal MySQL
const dbConfig = {
  host: process.env.DB_HOST || 'localhost',
  user: process.env.DB_USER || 'root',
  password: process.env.DB_PASSWORD || 'password',
  database: process.env.DB_NAME || 'email_templates',
  port: process.env.DB_PORT || 3306,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0
};

// Debug Log: Print config to console (masking password)
console.log('--- Database Configuration ---');
console.log(`Host: ${dbConfig.host}`);
console.log(`User: ${dbConfig.user}`);
console.log(`Database: ${dbConfig.database}`);
console.log(`Port: ${dbConfig.port}`);
console.log(`Password: ${dbConfig.password ? '******' : '(Not Set)'}`);
console.log('------------------------------');

let pool;

// Initialize DB Connection
const initDB = async () => {
  try {
    pool = mysql.createPool(dbConfig);
    
    // Test connection
    const connection = await pool.getConnection();
    console.log('Connected to MySQL database successfully.');
    connection.release();
    
    // Create table for MySQL
    await pool.query(`
      CREATE TABLE IF NOT EXISTS email_templates (
        id VARCHAR(255) PRIMARY KEY,
        template_key VARCHAR(255) UNIQUE NOT NULL,
        name VARCHAR(255) NOT NULL,
        description TEXT,
        subject VARCHAR(255),
        header_html TEXT,
        body_html TEXT,
        footer_html TEXT,
        full_html TEXT,
        required_variables JSON,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
      );
    `);
    
    console.log('Email templates table ready.');
  } catch (err) {
    console.error('Database initialization failed:', err);
    process.exit(1);
  }
};

initDB();

// API Routes
// GET All Templates
app.get('/api/templates', async (req, res) => {
  try {
    const [rows] = await pool.query('SELECT * FROM email_templates ORDER BY updated_at DESC');
    
    // Map DB fields back to frontend types
    const templates = rows.map(row => ({
      id: row.id,
      name: row.name,
      description: row.description,
      subject: row.subject,
      header: row.header_html,
      body: row.body_html,
      footer: row.footer_html,
      variables: typeof row.required_variables === 'string' ? JSON.parse(row.required_variables) : row.required_variables,
      updatedAt: row.updated_at
    }));
    
    res.json(templates);
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: 'Failed to fetch templates' });
  }
});

// SAVE (Upsert) Template
app.post('/api/templates', async (req, res) => {
  const t = req.body;
  
  // Ensure default values to prevent undefined errors
  const header = t.header || '';
  const body = t.body || '';
  const footer = t.footer || '';
  const fullHtml = `${header}${body}${footer}`;
  const templateKey = (t.name || '').trim().toLowerCase().replace(/\s+/g, '_').replace(/[^a-z0-9_]/g, '');
  const variablesJson = JSON.stringify(t.variables || []);
  
  const params = [
    t.id,
    templateKey,
    t.name,
    t.description || '',
    t.subject || '',
    header,
    body,
    footer,
    fullHtml,
    variablesJson
  ];
  
  try {
    const query = `
      INSERT INTO email_templates (id, template_key, name, description, subject, header_html, body_html, footer_html, full_html, required_variables, updated_at)
      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, NOW())
      ON DUPLICATE KEY UPDATE
        template_key = VALUES(template_key),
        name = VALUES(name),
        description = VALUES(description),
        subject = VALUES(subject),
        header_html = VALUES(header_html),
        body_html = VALUES(body_html),
        footer_html = VALUES(footer_html),
        full_html = VALUES(full_html),
        required_variables = VALUES(required_variables),
        updated_at = NOW();
    `;
    
    await pool.query(query, params);
    res.json({ success: true });
  } catch (err) {
    console.error("Save Template Error:", err);
    // Return specific error details to help debugging on the client
    res.status(500).json({ error: 'Failed to save template', details: err.message });
  }
});

// DELETE Template
app.delete('/api/templates/:id', async (req, res) => {
  try {
    await pool.query('DELETE FROM email_templates WHERE id = ?', [req.params.id]);
    res.json({ success: true });
  } catch (err) {
    console.error(err);
    res.status(500).json({ error: 'Failed to delete template' });
  }
});

// Handle React Routing
app.get('*', (req, res) => {
  res.sendFile(path.join(__dirname, 'dist', 'index.html'));
});

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});