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

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

const app = express();
const PORT = process.env.PORT || 3001;
const IS_PRODUCTION = process.env.NODE_ENV === 'production';

// 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 — restrict CORS in production
const corsOptions = IS_PRODUCTION
  ? { origin: process.env.CORS_ORIGIN || false }
  : { origin: true };
app.use(cors(corsOptions));
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));

// In production, serve the Vite-built client
if (IS_PRODUCTION) {
  const clientDist = join(__dirname, 'dist');
  app.use(express.static(clientDist));
}

// Map MIME types to file extensions
const MIME_TO_EXT = {
  'image/jpeg': 'jpg',
  'image/png': 'png',
  'image/webp': 'webp',
};

// Configure multer for image uploads
const storage = multer.diskStorage({
  destination: (_req, _file, cb) => {
    cb(null, uploadsDir);
  },
  filename: (_req, file, cb) => {
    const ext = MIME_TO_EXT[file.mimetype] || 'bin';
    cb(null, `${uuidv4()}.${ext}`);
  },
});

const fileFilter = (_req, file, cb) => {
  if (MIME_TO_EXT[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 },
});

// ── API Routes ──────────────────────────────────────────────────────────────

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

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

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

    // Create preview by resizing to max 1000px
    const previewFilename = `${uuidv4()}.png`;
    const previewDir = join(uploadsDir, 'preview');
    if (!existsSync(previewDir)) mkdirSync(previewDir, { recursive: true });

    await sharp(req.file.path)
      .resize({ width: 1000, height: 1000, fit: 'inside' })
      .png()
      .toFile(join(previewDir, previewFilename));

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

// High-resolution export (300×300 → 4500×4500 @ 300 DPI)
const EXPORT_SCALE = 15;
const EXPORT_SIZE = 4500;

app.post('/api/export', async (req, res) => {
  try {
    const { elements, designName = 'design', template } = req.body;

    if (!elements || !Array.isArray(elements)) {
      return res.status(400).json({ error: 'Elements array is required' });
    }

    const canvas = createCanvas(EXPORT_SIZE, EXPORT_SIZE);
    const ctx = canvas.getContext('2d');

    // Template background
    if (template?.background) {
      const bg = template.background;
      if (bg.type === 'color') {
        ctx.fillStyle = bg.color;
        ctx.fillRect(0, 0, EXPORT_SIZE, EXPORT_SIZE);
      } else if (bg.type === 'image' && bg.src) {
        try {
          const imgUrl = bg.src.startsWith('/')
            ? join(__dirname, bg.src.replace('/uploads', 'uploads'))
            : bg.src;
          const img = await loadImage(imgUrl);
          ctx.drawImage(img, 0, 0, EXPORT_SIZE, EXPORT_SIZE);
        } catch (imgError) {
          console.error('Failed to load template background:', imgError);
          ctx.fillStyle = '#ffffff';
          ctx.fillRect(0, 0, EXPORT_SIZE, EXPORT_SIZE);
        }
      }
    } else {
      ctx.fillStyle = '#ffffff';
      ctx.fillRect(0, 0, EXPORT_SIZE, EXPORT_SIZE);
    }

    // Render a single element
    const renderElement = async (el) => {
      ctx.save();

      const x = (el.x || 0) * EXPORT_SCALE;
      const y = (el.y || 0) * EXPORT_SCALE;
      const centerX = x + ((el.width || el.fontSize || 100) * EXPORT_SCALE) / 2;
      const centerY = y + ((el.height || el.fontSize || 100) * EXPORT_SCALE) / 2;

      ctx.translate(centerX, centerY);
      ctx.rotate(((el.rotation || 0) * Math.PI) / 180);
      ctx.translate(-centerX, -centerY);

      if (el.type === 'image' && el.src) {
        try {
          const imgUrl = el.src.startsWith('/')
            ? join(__dirname, el.src.replace('/uploads', 'uploads'))
            : el.src;
          const img = await loadImage(imgUrl);
          const width = (el.width || 100) * EXPORT_SCALE;
          const height = (el.height || 100) * EXPORT_SCALE;

          if (el.crop) {
            ctx.drawImage(img, el.crop.sx, el.crop.sy, el.crop.sWidth, el.crop.sHeight, x, y, width, height);
          } else {
            ctx.drawImage(img, x, y, width, height);
          }
        } catch (imgError) {
          console.error('Failed to load image for export:', imgError);
        }
      } else if (el.type === 'text') {
        const fontSize = ((el.fontSize || 32) * EXPORT_SCALE) / 32;
        ctx.font = `${fontSize}px "${el.fontFamily || 'Arial'}"`;
        ctx.fillStyle = el.fill || '#000000';
        ctx.textAlign = 'center';
        ctx.textBaseline = 'middle';
        ctx.fillText(el.text || '', centerX, centerY);
      }

      ctx.restore();
    };

    // Render user elements
    for (const el of elements) {
      if (el.nonPrintable) continue;
      await renderElement(el);
    }

    // Render template overlay
    if (template?.overlay) {
      for (const overlayEl of template.overlay) {
        if (overlayEl.nonPrintable) continue;
        await renderElement(overlayEl);
      }
    }

    // Save to file
    const exportFilename = `${designName.replace(/[^a-z0-9]/gi, '_')}_${uuidv4()}.png`;
    const exportPath = join(exportsDir, exportFilename);
    writeFileSync(exportPath, canvas.toBuffer('image/png'));

    res.json({
      success: true,
      export: {
        url: `/exports/${exportFilename}`,
        filename: exportFilename,
        width: EXPORT_SIZE,
        height: EXPORT_SIZE,
        dpi: 300,
        sizeInches: '15x15',
      },
    });
  } catch (error) {
    console.error('Export error:', error);
    res.status(500).json({ error: 'Failed to export design', details: error.message });
  }
});

// Download
app.get('/api/download/:filename', (req, res) => {
  const filePath = join(exportsDir, req.params.filename);
  if (!existsSync(filePath)) {
    return res.status(404).json({ error: 'File not found' });
  }
  res.download(filePath);
});

// API 404 catch-all (before SPA catch-all)
app.all('/api/*', (_req, res) => {
  res.status(404).json({ error: 'API route not found' });
});

// In production, SPA catch-all
if (IS_PRODUCTION) {
  app.get('*', (_req, res) => {
    res.sendFile(join(__dirname, 'dist', 'index.html'));
  });
}

// Error handling
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 });
  }
  console.error('Unhandled error:', err);
  res.status(500).json({ error: 'Internal server error', details: err.message });
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
  console.log(`Mode: ${IS_PRODUCTION ? 'production' : 'development'}`);
});