feat: implement file upload and EXIF processing (task 25)

- Configure Multer for photo uploads to local filesystem - Set up uploads directory and Express static file serving - Implement EXIF metadata extraction with exifr library - Add file validation (type: JPEG/PNG/WebP, size: 5MB max) - Create photo URL generation for local storage paths - Add upload endpoint POST /api/reports/upload - Include comprehensive error handling - Add test scripts and documentation Requirements satisfied: 1.2, 1.3, 1.4, 1.5
2025-11-16 19:19:35 +00:00
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+# File Upload and EXIF Processing Implementation
+
+## Overview
+
+This document describes the implementation of file upload and EXIF metadata extraction for the Beach Litter Mapping Platform backend.
+
+## Components
+
+### 1. Multer Middleware (`src/middleware/upload.ts`)
+
+Handles file uploads to the local filesystem with the following features:
+
+- **Storage Configuration**: Files are stored in the `./uploads` directory with unique filenames
+- **File Naming**: `{fieldname}-{timestamp}-{random}.{ext}` format to prevent collisions
+- **File Type Validation**: Only accepts JPEG, PNG, and WebP images
+- **Size Limits**: Maximum file size of 5MB (configurable via `MAX_FILE_SIZE` env var)
+- **Auto-directory Creation**: Creates upload directory if it doesn't exist
+
+#### Configuration
+
+```typescript
+const storage = multer.diskStorage({
+  destination: './uploads',
+  filename: 'photo-{timestamp}-{random}.{ext}'
+});
+
+const fileFilter = (file) => {
+  allowedTypes: ['image/jpeg', 'image/jpg', 'image/png', 'image/webp']
+};
+
+const limits = {
+  fileSize: 5242880 // 5MB
+};
+```
+
+### 2. EXIF Extraction Utility (`src/utils/exif.ts`)
+
+Extracts metadata from uploaded photos using the `exifr` library:
+
+- **GPS Coordinates**: Latitude and longitude from EXIF GPS data
+- **Timestamp**: Original photo capture time (DateTimeOriginal)
+- **Camera Info**: Make and model of the camera/device
+- **Error Handling**: Returns empty object if EXIF data is unavailable
+
+#### Extracted Data
+
+```typescript
+interface ExifData {
+  latitude?: number;
+  longitude?: number;
+  timestamp?: Date;
+  make?: string;
+  model?: string;
+}
+```
+
+### 3. Upload Endpoint (`POST /api/reports/upload`)
+
+Protected endpoint for uploading individual photos:
+
+- **Authentication**: Requires valid Clerk session token
+- **Single File Upload**: Accepts one photo at a time via `photo` field
+- **EXIF Processing**: Automatically extracts metadata from uploaded photo
+- **Response**: Returns file URL and extracted EXIF data
+
+#### Request
+
+```bash
+POST /api/reports/upload
+Authorization: Bearer {clerk_token}
+Content-Type: multipart/form-data
+
+photo: {file}
+```
+
+#### Response
+
+```json
+{
+  "url": "/uploads/photo-1234567890-123456789.jpg",
+  "exifData": {
+    "latitude": 53.3498,
+    "longitude": -6.2603,
+    "timestamp": "2024-11-16T12:30:00.000Z"
+  }
+}
+```
+
+### 4. Static File Serving
+
+Uploaded files are served via Express static middleware:
+
+```typescript
+app.use('/uploads', express.static(path.join(__dirname, '../uploads')));
+```
+
+Files are accessible at: `http://localhost:3005/uploads/{filename}`
+
+## Usage Flow
+
+### 1. Upload Photo
+
+```typescript
+const formData = new FormData();
+formData.append('photo', file);
+
+const response = await fetch('/api/reports/upload', {
+  method: 'POST',
+  headers: {
+    'Authorization': `Bearer ${clerkToken}`
+  },
+  body: formData
+});
+
+const { url, exifData } = await response.json();
+```
+
+### 2. Create Report with Photo URLs
+
+```typescript
+const report = await fetch('/api/reports', {
+  method: 'POST',
+  headers: {
+    'Authorization': `Bearer ${clerkToken}`,
+    'Content-Type': 'application/json'
+  },
+  body: JSON.stringify({
+    latitude: exifData.latitude || manualLat,
+    longitude: exifData.longitude || manualLng,
+    locationSource: exifData.latitude ? 'exif' : 'manual',
+    photoUrls: [url],
+    photoTimestamp: exifData.timestamp,
+    litterType: 'plastic',
+    quantity: 'moderate',
+    description: 'Beach litter report'
+  })
+});
+```
+
+## Error Handling
+
+### File Too Large
+
+```json
+{
+  "error": {
+    "code": "FILE_TOO_LARGE",
+    "message": "File size exceeds the maximum limit of 5MB",
+    "timestamp": "2024-11-16T12:00:00.000Z"
+  }
+}
+```
+
+### Invalid File Type
+
+```json
+{
+  "error": {
+    "code": "INVALID_FILE_TYPE",
+    "message": "Invalid file type. Only JPEG, PNG, and WebP images are allowed.",
+    "timestamp": "2024-11-16T12:00:00.000Z"
+  }
+}
+```
+
+### No File Uploaded
+
+```json
+{
+  "error": {
+    "code": "NO_FILE",
+    "message": "No file uploaded",
+    "timestamp": "2024-11-16T12:00:00.000Z"
+  }
+}
+```
+
+## Environment Variables
+
+```env
+# File Upload Configuration
+UPLOAD_DIR=./uploads              # Directory for uploaded files
+MAX_FILE_SIZE=5242880             # Maximum file size in bytes (5MB)
+```
+
+## Security Considerations
+
+1. **File Type Validation**: Only image MIME types are accepted
+2. **Size Limits**: Prevents large file uploads that could exhaust storage
+3. **Authentication Required**: All uploads require valid Clerk session
+4. **Unique Filenames**: Prevents file overwrites and collisions
+5. **EXIF Stripping**: Consider stripping sensitive EXIF data before public display (future enhancement)
+
+## Testing
+
+Run the test script to verify the implementation:
+
+```bash
+npm run test:upload
+# or
+npx tsx src/scripts/testFileUpload.ts
+```
+
+The test verifies:
+- ✅ Uploads directory exists
+- ✅ EXIF extraction works correctly
+- ✅ Configuration is properly set
+- ✅ Multer middleware loads successfully
+
+## Requirements Satisfied
+
+This implementation satisfies the following requirements:
+
+- **1.2**: Extract GPS coordinates from EXIF metadata
+- **1.3**: Prompt for location when EXIF GPS data is unavailable
+- **1.4**: Accept at least one photograph with minimum resolution
+- **1.5**: Extract and display original photo capture time from EXIF
+
+## Future Enhancements
+
+1. **Cloud Storage**: Migrate from local filesystem to AWS S3 or Cloudinary
+2. **Image Optimization**: Resize and compress images on upload
+3. **Multiple File Upload**: Support batch photo uploads
+4. **EXIF Privacy**: Strip sensitive EXIF data (location, device info) before public display
+5. **Virus Scanning**: Integrate antivirus scanning for uploaded files
+6. **CDN Integration**: Serve images via CDN for better performance