import express from 'express';
import cors from 'cors';
import multer from 'multer';
import { v4 as uuidv4 } from 'uuid';
import sharp from 'sharp';
import { fileURLToPath } from 'module';
import { dirname, join } from 'path';
import { mkdirSync, existsSync } from 'fs';

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

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

// Ensure upload and export directories exist
const uploadsDir = join(__dirname, 'uploads');
const exportsDir = join(__dirname, 'exports');
[uploadsDir, exportsDir].forEach(dir => {
  if (!existsSync(dir)) mkdirSync(dir, { recursive: true });
});

// Middleware
app.use(cors());
app.use(express.json({ limit: '50mb' }));
app.use(express.urlencoded({ extended: true, limit: '50mb' }));

// Serve static files for uploads and exports
app.use('/uploads', express.static(uploadsDir));
app.use('/exports', express.static(exportsDir));

// Configure multer for image uploads
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, uploadsDir);
  },
  filename: (req, file, cb) => {
    const ext = file.originalname.split('.').pop();
    const filename = `${uuidv4()}.${ext}`;
    cb(null, filename);
  }
});

const fileFilter = (req, file, cb) => {
  const allowedTypes = ['image/jpeg', 'image/png', 'image/webp'];
  if (allowedTypes.includes(file.mimetype)) {
    cb(null, true);
  } else {
    cb(new Error('Invalid file type. Only JPEG, PNG, and WebP are allowed.'), false);
  }
};

const upload = multer({
  storage,
  fileFilter,
  limits: {
    fileSize: 20 * 1024 * 1024 // 20MB
  }
});

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

// Upload endpoint
app.post('/api/upload', upload.single('image'), async (req, res) => {
  try {
    if (!req.file) {
      return res.status(400).json({ error: 'No file uploaded' });
    }

    const originalPath = req.file.path;
    const originalUrl = `/uploads/${req.file.filename}`;

    // Create preview by resizing to max 1000px
    const previewFilename = req.file.filename.replace(/\.[^.]+$/, '.png');
    const previewPath = join(uploadsDir, 'preview', previewFilename);

    // Ensure preview directory exists
    const previewDir = join(uploadsDir, 'preview');
    if (!existsSync(previewDir)) mkdirSync(previewDir, { recursive: true });

    await sharp(originalPath)
      .resize({ width: 1000, height: 1000, fit: 'inside' })
      .png()
      .toFile(previewPath);

    const previewUrl = `/uploads/preview/${previewFilename}`;

    res.json({
      success: true,
      original: {
        path: originalPath,
        url: originalUrl,
        filename: req.file.filename,
        size: req.file.size,
        mimetype: req.file.mimetype
      },
      preview: {
        path: previewPath,
        url: previewUrl,
        filename: previewFilename
      }
    });
  } catch (error) {
    console.error('Upload error:', error);
    res.status(500).json({ error: 'Failed to process upload', details: error.message });
  }
});

// Error handling for multer
app.use((err, req, res, next) => {
  if (err instanceof multer.MulterError) {
    if (err.code === 'LIMIT_FILE_SIZE') {
      return res.status(400).json({ error: 'File too large. Maximum size is 20MB.' });
    }
    return res.status(400).json({ error: err.message });
  }
  next(err);
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
  console.log(`Health check: http://localhost:${PORT}/api/health`);
  console.log(`Upload endpoint: POST http://localhost:${PORT}/api/upload`);
});