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;

// 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));

// Serve built client static files
const clientDistDir = join(__dirname, 'dist');
if (existsSync(clientDistDir)) {
  app.use(express.static(clientDistDir));

  // Serve index.html for all non-API routes (SPA routing)
  app.get('*', (req, res, next) => {
    if (!req.path.startsWith('/api') && !req.path.startsWith('/uploads') && !req.path.startsWith('/exports')) {
      res.sendFile(join(clientDistDir, 'index.html'));
    } else {
      next();
    }
  });
}

// 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);
});

// High-resolution export endpoint (300x300px -> 4500x4500px @ 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');

    // Render template background layer first (if template active)
    if (template && 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 {
      // Default white background
      ctx.fillStyle = '#ffffff';
      ctx.fillRect(0, 0, EXPORT_SIZE, EXPORT_SIZE);
    }

    // Helper function to 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;

          // Apply crop if slot crop region specified
          if (el.crop) {
            const { sx, sy, sWidth, sHeight } = el.crop;
            ctx.drawImage(
              img,
              sx, sy, sWidth, sHeight, // source crop
              x, y, width, height // destination
            );
          } 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) {
      // Skip non-printable elements (guides, watermarks, template-only layers)
      if (el.nonPrintable) continue;
      await renderElement(el);
    }

    // Render template overlay layer last (if template active)
    if (template && 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);
    const buffer = canvas.toBuffer('image/png');
    writeFileSync(exportPath, buffer);

    res.json({
      success: true,
      export: {
        url: `/exports/${exportFilename}`,
        path: exportPath,
        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 });
  }
});

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`);
});