brotli_impl.go

package compression

import (
	"io"

	"github.com/andybalholm/brotli"
)

// isBrotliAvailable checks if brotli compression is available.
//
// This function checks if the github.com/andybalholm/brotli package
// is available and can be used for compression. It's used internally
// by BrotliProvider to determine if brotli compression should be
// offered to clients.
//
// The function returns true if the brotli package is available,
// false otherwise. This allows the compression package to gracefully
// handle cases where brotli is not available without causing
// compilation errors.
//
// Returns:
//   - bool: true if brotli compression is available, false otherwise
//
// Example:
//
//	// This function is used internally by BrotliProvider
//	if isBrotliAvailable() {
//		fmt.Println("Brotli compression is available")
//	} else {
//		fmt.Println("Brotli compression is not available")
//	}
func isBrotliAvailable() bool {
	return true
}

// newBrotliWriter creates a new brotli writer.
//
// This function creates a new brotli.Writer with the specified
// compression level and output writer. It handles the mapping
// of compression levels to brotli's quality settings.
//
// Compression level mapping:
//   - 0: brotli.BestSpeed (fastest compression)
//   - 1-10: Direct mapping to brotli quality levels
//   - 11: brotli.BestCompression (best compression)
//
// Args:
//   - w: The output writer to compress to
//   - level: The compression level (0-11)
//
// Returns:
//   - io.WriteCloser: A brotli compression writer
//   - error: Any error that occurred during creation
//
// Example:
//
//	// Create a brotli writer with maximum compression
//	writer, err := newBrotliWriter(responseWriter, 11)
//	if err != nil {
//		return err
//	}
//	defer writer.Close()
//
//	// Use the writer
//	_, err = writer.Write([]byte("Hello, World!"))
func newBrotliWriter(w io.Writer, level int) (io.WriteCloser, error) {
	// Brotli levels are 0-11, but we need to map them to brotli.WriterOptions
	// Level 0 = brotli.BestSpeed, Level 11 = brotli.BestCompression
	var quality int
	switch {
	case level <= 0:
		quality = brotli.BestSpeed
	case level >= 11:
		quality = brotli.BestCompression
	default:
		// Map 1-10 to appropriate quality levels
		quality = level
	}

	return brotli.NewWriterLevel(w, quality), nil
}