var (
	// Uncompressed indicates no compression.
	Uncompressed = uncompressedType{}

	// Gzip is used for blob data.
	Gzip = gzipType{}

	// EStargz is used for estargz data.
	EStargz = estargzType{}

	// Zstd is used for Zstandard data.
	Zstd = zstdType{}
)

var Default gzipType = Gzip

var EStargzAnnotations = []string{estargz.TOCJSONDigestAnnotation, estargz.StoreUncompressedSizeAnnotation}

type Compressor func(dest io.Writer, mediaType string) (io.WriteCloser, error)

type Config struct {
	Type  Type
	Force bool
	Level *int
}

type Decompressor func(ctx context.Context, cs content.Store, desc ocispecs.Descriptor) (io.ReadCloser, error)

type Finalizer func(context.Context, content.Store) (map[string]string, error)

type Type interface {
	Compress(ctx context.Context, comp Config) (compressorFunc Compressor, finalize Finalizer)
	Decompress(ctx context.Context, cs content.Store, desc ocispecs.Descriptor) (io.ReadCloser, error)
	NeedsConversion(ctx context.Context, cs content.Store, desc ocispecs.Descriptor) (bool, error)
	NeedsComputeDiffBySelf() bool
	OnlySupportOCITypes() bool
	NeedsForceCompression() bool
	MediaType() string
	String() string
}