File Storage

// New creates a Storage instance from config.
// Automatically creates the bucket if it doesn't exist.
func New(cfg config.StorageConfig) (*Storage, error)

// Upload stores a file in the bucket at the given key.
func (s *Storage) Upload(ctx context.Context, key string, reader io.Reader, contentType string) error

// Download retrieves a file from the bucket.
func (s *Storage) Download(ctx context.Context, key string) (io.ReadCloser, error)

// Delete removes a file from the bucket.
func (s *Storage) Delete(ctx context.Context, key string) error

// GetURL returns the public URL for a stored file.
func (s *Storage) GetURL(key string) string

// GetSignedURL returns a pre-signed URL valid for the given duration.
func (s *Storage) GetSignedURL(ctx context.Context, key string, duration time.Duration) (string, error)

const MaxImageWidth = 1920   // Maximum width for processed images
const ThumbnailSize = 300    // Size of generated thumbnails

// ProcessImage resizes an image if it exceeds MaxImageWidth.
// Preserves aspect ratio. Returns processed bytes.
func ProcessImage(reader io.Reader, mimeType string) ([]byte, error)

// GenerateThumbnail creates a square thumbnail (300x300).
// Uses center-crop with Lanczos resampling.
func GenerateThumbnail(reader io.Reader, mimeType string) ([]byte, error)

// IsImageMimeType returns true for supported image formats.
// Supports: image/jpeg, image/png, image/gif
func IsImageMimeType(mimeType string) bool

// MaxUploadSize is the maximum file size (50 MB).
const MaxUploadSize = 50 << 20

var AllowedMimeTypes = map[string]bool{
    "image/jpeg":      true,
    "image/png":       true,
    "image/gif":       true,
    "image/webp":      true,
    "video/mp4":       true,
    "video/webm":      true,
    "video/quicktime": true,
    "application/pdf": true,
    "text/plain":      true,
    "text/csv":        true,
    "application/json": true,
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet": true,
    "application/vnd.openxmlformats-officedocument.wordprocessingml.document": true,
}

POST /api/uploads (multipart/form-data)
  1. Validate file size (max 50 MB)
  2. Validate MIME type (AllowedMimeTypes)
  3. Generate unique filename: {timestamp}-{original_name}.{ext}
  4. Upload to S3 at key: uploads/{year}/{month}/{filename}
  5. Save Upload record to database
  6. If image -> enqueue ProcessImage background job
  7. Return { data: upload, message: "File uploaded successfully" }