import http from 'http';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import { createAiCore, UpstreamError } from './server/aiCore.js';

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

const PORT = process.env.PORT || 7860;
const HOST = process.env.HOST || '0.0.0.0';
const distDir = path.join(__dirname, 'dist');
const ai = createAiCore(process.env);

function sendJson(res, statusCode, payload) {
  res.writeHead(statusCode, {
    'Content-Type': 'application/json; charset=utf-8',
    'Cache-Control': 'no-store',
    'Access-Control-Allow-Origin': '*',
  });
  res.end(JSON.stringify(payload));
}

function readBody(req) {
  return new Promise((resolve, reject) => {
    let data = '';
    req.on('data', (chunk) => (data += chunk));
    req.on('end', () => resolve(data));
    req.on('error', reject);
  });
}

// MIME types mapping
const mimeTypes = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'application/javascript',
  '.mjs': 'application/javascript',
  '.css': 'text/css',
  '.json': 'application/json',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif': 'image/gif',
  '.svg': 'image/svg+xml',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
  '.ttf': 'font/ttf',
  '.eot': 'application/vnd.ms-fontobject',
};

function getMimeType(filePath) {
  const ext = path.extname(filePath).toLowerCase();
  return mimeTypes[ext] || 'application/octet-stream';
}

function serveFile(res, filePath, statusCode = 200) {
  try {
    const content = fs.readFileSync(filePath);
    const mimeType = getMimeType(filePath);
    res.writeHead(statusCode, {
      'Content-Type': mimeType,
      'Cache-Control': 'public, max-age=3600',
      'Access-Control-Allow-Origin': '*',
    });
    res.end(content);
  } catch (err) {
    console.error(`Error serving file ${filePath}:`, err);
    res.writeHead(500, { 'Content-Type': 'text/plain' });
    res.end('Internal Server Error');
  }
}

const server = http.createServer((req, res) => {
  // Set CORS headers
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (req.method === 'OPTIONS') {
    res.writeHead(200);
    res.end();
    return;
  }

  // Remove query string from URL
  const urlPath = req.url.split('?')[0];

  // API routes (production)
  if (urlPath === '/api/ai/ping' && req.method === 'GET') {
    return sendJson(res, 200, ai.ping());
  }

  if (urlPath === '/api/ai/mix' && req.method === 'POST') {
    return (async () => {
      try {
        const raw = await readBody(req);
        const parsed = raw ? JSON.parse(raw) : {};
        const result = await ai.mix({
          substances: parsed.substances || [],
          temperatureC: parsed.temperatureC,
        });
        return sendJson(res, 200, result);
      } catch (err) {
        const triedModels = err?.triedModels || [];
        const lastModel = err?.lastModel || null;

        if (err instanceof UpstreamError) {
          if (err.status === 401 || err.status === 403) {
            return sendJson(res, 401, { error: 'API key Groq invalide ou non autorisee', triedModels, lastModel });
          }
          if (err.status === 429) {
            return sendJson(res, 429, { error: 'Quota/limite Groq atteinte (429). Reessaye plus tard.', triedModels, lastModel });
          }
          if (err.status >= 400 && err.status < 500) {
            return sendJson(res, err.status, { error: err.upstreamMessage || err.message, triedModels, lastModel });
          }
          return sendJson(res, 502, { error: 'Erreur upstream Groq lors de la generation IA', details: err.message, triedModels, lastModel });
        }

        return sendJson(res, 500, { error: 'Erreur serveur /api/ai/mix', details: err?.message || String(err), triedModels, lastModel });
      }
    })();
  }

  let filePath = path.join(distDir, urlPath === '/' ? 'index.html' : urlPath);

  // Normalize path to prevent directory traversal
  filePath = path.normalize(filePath);
  if (!filePath.startsWith(distDir)) {
    res.writeHead(403, { 'Content-Type': 'text/plain' });
    res.end('Forbidden');
    return;
  }

  // Check if file exists
  try {
    const stats = fs.statSync(filePath);
    if (stats.isFile()) {
      serveFile(res, filePath);
    } else if (stats.isDirectory()) {
      // Try to serve index.html from the directory
      const indexPath = path.join(filePath, 'index.html');
      if (fs.existsSync(indexPath)) {
        serveFile(res, indexPath);
      } else {
        res.writeHead(404, { 'Content-Type': 'text/plain' });
        res.end('Not Found');
      }
    }
  } catch (err) {
    // File not found, serve index.html for SPA routing
    const indexPath = path.join(distDir, 'index.html');
    if (fs.existsSync(indexPath)) {
      serveFile(res, indexPath, 200);
    } else {
      res.writeHead(404, { 'Content-Type': 'text/plain' });
      res.end('Not Found');
    }
  }
});

server.listen(PORT, HOST, () => {
  console.log(`\n✓ Server is running!`);
  console.log(`✓ Listening on http://${HOST}:${PORT}`);
  console.log(`✓ Environment: ${process.env.NODE_ENV || 'development'}`);
});

process.on('SIGTERM', () => {
  console.log('SIGTERM received, shutting down gracefully...');
  server.close(() => {
    console.log('Server closed');
    process.exit(0);
  });
});

process.on('SIGINT', () => {
  console.log('SIGINT received, shutting down gracefully...');
  server.close(() => {
    console.log('Server closed');
    process.exit(0);
  });
});