package services

import "io"

// StorageBackend abstracts where files are physically stored.
// The StorageService handles validation, encryption, and URL generation,
// then delegates raw I/O to the backend.
type StorageBackend interface {
	// Write stores data at the given key (e.g., "images/20240101_uuid.jpg").
	Write(key string, data []byte) error

	// Read returns the raw bytes stored at the given key.
	Read(key string) ([]byte, error)

	// Delete removes the object at the given key. Returns nil if not found.
	Delete(key string) error

	// ReadStream returns a reader for the object (used for large files).
	// Callers must close the returned ReadCloser.
	ReadStream(key string) (io.ReadCloser, error)
}