Add backend server with API endpoints

backend/src/server.js

@@ -0,0 +1,157 @@
+const express = require('express');
+const cors = require('cors');
+const helmet = require('helmet');
+const multer = require('multer');
+const sharp = require('sharp');
+const path = require('path');
+const fs = require('fs').promises;
+require('dotenv').config();
+
+const app = express();
+const PORT = process.env.PORT || 3000;
+const MAX_FILE_SIZE = (process.env.MAX_FILE_SIZE || 10) * 1024 * 1024;
+
+// Middleware
+app.use(helmet());
+app.use(cors());
+app.use(express.json());
+
+// Serve static frontend
+app.use(express.static(path.join(__dirname, '../public')));
+
+// Configure multer for memory storage
+const upload = multer({
+  storage: multer.memoryStorage(),
+  limits: { fileSize: MAX_FILE_SIZE },
+  fileFilter: (req, file, cb) => {
+    if (file.mimetype === 'image/png') {
+      cb(null, true);
+    } else {
+      cb(new Error('Only PNG files are allowed'));
+    }
+  }
+});
+
+// Health check endpoint
+app.get('/api/health', (req, res) => {
+  res.json({ status: 'ok', timestamp: new Date().toISOString() });
+});
+
+// Process image endpoint
+app.post('/api/process', upload.single('image'), async (req, res) => {
+  try {
+    if (!req.file) {
+      return res.status(400).json({ error: 'No image file provided' });
+    }
+
+    const { width, height, quality, maintainAspectRatio } = req.body;
+
+    // Parse dimensions
+    const targetWidth = width ? parseInt(width) : null;
+    const targetHeight = height ? parseInt(height) : null;
+    const compressionQuality = quality ? parseInt(quality) : 80;
+
+    // Validate inputs
+    if (targetWidth && (targetWidth < 1 || targetWidth > 10000)) {
+      return res.status(400).json({ error: 'Width must be between 1 and 10000' });
+    }
+    if (targetHeight && (targetHeight < 1 || targetHeight > 10000)) {
+      return res.status(400).json({ error: 'Height must be between 1 and 10000' });
+    }
+    if (compressionQuality < 1 || compressionQuality > 100) {
+      return res.status(400).json({ error: 'Quality must be between 1 and 100' });
+    }
+
+    // Process image with Sharp
+    let pipeline = sharp(req.file.buffer);
+
+    // Resize if dimensions provided
+    if (targetWidth || targetHeight) {
+      const resizeOptions = {
+        width: targetWidth,
+        height: targetHeight,
+        fit: maintainAspectRatio === 'true' ? 'inside' : 'fill'
+      };
+      pipeline = pipeline.resize(resizeOptions);
+    }
+
+    // Apply PNG compression
+    pipeline = pipeline.png({
+      quality: compressionQuality,
+      compressionLevel: 9,
+      adaptiveFiltering: true
+    });
+
+    // Convert to buffer
+    const processedBuffer = await pipeline.toBuffer();
+
+    // Get metadata for response
+    const metadata = await sharp(processedBuffer).metadata();
+
+    // Send processed image
+    res.set({
+      'Content-Type': 'image/png',
+      'Content-Length': processedBuffer.length,
+      'Content-Disposition': `attachment; filename="processed-${Date.now()}.png"`,
+      'X-Image-Width': metadata.width,
+      'X-Image-Height': metadata.height,
+      'X-Original-Size': req.file.size,
+      'X-Processed-Size': processedBuffer.length
+    });
+
+    res.send(processedBuffer);
+
+  } catch (error) {
+    console.error('Image processing error:', error);
+    res.status(500).json({ error: 'Failed to process image', details: error.message });
+  }
+});
+
+// Get image metadata endpoint
+app.post('/api/metadata', upload.single('image'), async (req, res) => {
+  try {
+    if (!req.file) {
+      return res.status(400).json({ error: 'No image file provided' });
+    }
+
+    const metadata = await sharp(req.file.buffer).metadata();
+
+    res.json({
+      width: metadata.width,
+      height: metadata.height,
+      format: metadata.format,
+      size: req.file.size,
+      hasAlpha: metadata.hasAlpha,
+      channels: metadata.channels
+    });
+
+  } catch (error) {
+    console.error('Metadata extraction error:', error);
+    res.status(500).json({ error: 'Failed to extract metadata', details: error.message });
+  }
+});
+
+// Error handling middleware
+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. Max size is ${MAX_FILE_SIZE / 1024 / 1024}MB` });
+    }
+    return res.status(400).json({ error: err.message });
+  }
+  
+  console.error('Server error:', err);
+  res.status(500).json({ error: 'Internal server error' });
+});
+
+// Serve frontend for all other routes
+app.get('*', (req, res) => {
+  res.sendFile(path.join(__dirname, '../public/index.html'));
+});
+
+// Start server
+app.listen(PORT, () => {
+  console.log(`PNGer server running on port ${PORT}`);
+  console.log(`Environment: ${process.env.NODE_ENV || 'development'}`);
+  console.log(`Max file size: ${MAX_FILE_SIZE / 1024 / 1024}MB`);
+});