fs

type Archive interface {
	// Apply decompresses the compressed stream represented by reader `r` and
	// applies it to the directory `root`.
	Apply(ctx context.Context, root string, r io.Reader, opts ...archive.ApplyOpt) (int64, error)
}

type Fetcher interface {
	// Fetch fetches the artifact identified by the descriptor. It first checks the local content store
	// and returns a `ReadCloser` from there. Otherwise it fetches from the remote, saves in the local content store
	// and then returns a `ReadCloser`.
	Fetch(ctx context.Context, desc ocispec.Descriptor) (io.ReadCloser, bool, error)
	// Store takes in a descriptor and io.Reader and stores it in the local store.
	Store(ctx context.Context, desc ocispec.Descriptor, reader io.Reader) error
}

type IndexSelectionPolicy func([]ocispec.Descriptor) (ocispec.Descriptor, error)

type Inner interface {
	content.Storage
	ReferrersCaller
}

type OCIArtifactClient struct {
	Inner
}

type Option func(*options)

type ReferrersCaller interface {
	Referrers(ctx context.Context, desc ocispec.Descriptor, artifactType string, fn func(referrers []ocispec.Descriptor) error) error
}

type ReferrersClient interface {
	/// Takes in an manifest descriptor and IndexSelectionPolicy and returns a single artifact descriptor.
	/// Returns an error (ErrNoReferrers) if the manifest descriptor has no referrers.
	SelectReferrer(context.Context, ocispec.Descriptor, IndexSelectionPolicy) (ocispec.Descriptor, error)
}

type Unpacker interface {
	// Unpack takes care of getting the layer specified by descriptor `desc`,
	// decompressing it, putting it in the directory with the path `mountpoint`
	// and applying the difference to the parent layers if there is any.
	// After that the layer can be mounted as non-remote snapshot.
	Unpack(ctx context.Context, desc ocispec.Descriptor, mountpoint string, mounts []mount.Mount) error
}