const (
	ManifestOSFeatureNydus   = "nydus.remoteimage.v1"
	MediaTypeNydusBlob       = "application/vnd.oci.image.layer.nydus.blob.v1"
	BootstrapFileNameInLayer = "image/image.boot"

	ManifestNydusCache = "containerd.io/snapshot/nydus-cache"

	LayerAnnotationFSVersion          = "containerd.io/snapshot/nydus-fs-version"
	LayerAnnotationNydusBlob          = "containerd.io/snapshot/nydus-blob"
	LayerAnnotationNydusBlobDigest    = "containerd.io/snapshot/nydus-blob-digest"
	LayerAnnotationNydusBlobSize      = "containerd.io/snapshot/nydus-blob-size"
	LayerAnnotationNydusBootstrap     = "containerd.io/snapshot/nydus-bootstrap"
	LayerAnnotationNydusSourceChainID = "containerd.io/snapshot/nydus-source-chainid"
	LayerAnnotationNydusEncryptedBlob = "containerd.io/snapshot/nydus-encrypted-blob"
	LayerAnnotationNydusSourceDigest  = "containerd.io/snapshot/nydus-source-digest"
	LayerAnnotationNydusTargetDigest  = "containerd.io/snapshot/nydus-target-digest"

	LayerAnnotationNydusReferenceBlobIDs = "containerd.io/snapshot/nydus-reference-blob-ids"

	LayerAnnotationUncompressed = "containerd.io/uncompressed"
)

const EntryBlob = "image.blob"

const EntryBlobMeta = "blob.meta"

const EntryBlobMetaHeader = "blob.meta.header"

const EntryBootstrap = "image.boot"

const EntryTOC = "rafs.blob.toc"

var (
	ErrNotFound = errors.New("data not found")
)

type Backend interface {
	// Push pushes specified blob file to remote storage backend.
	Push(ctx context.Context, cs content.Store, desc ocispec.Descriptor) error
	// Check checks whether a blob exists in remote storage backend,
	// blob exists -> return (blobPath, nil)
	// blob not exists -> return ("", err)
	Check(blobDigest digest.Digest) (string, error)
	// Type returns backend type name.
	Type() string
}

type Compressor = uint32

const (
	CompressorNone     Compressor = 0x0000_0001
	CompressorZstd     Compressor = 0x0000_0002
	CompressorLz4Block Compressor = 0x0000_0004
	CompressorMask     Compressor = 0x0000_000f
)

type Encrypter = func(context.Context, content.Store, ocispec.Descriptor) (ocispec.Descriptor, error)

type File struct {
	Name   string
	Reader io.Reader
	Size   int64
}

type Layer struct {
	// Digest represents the hash of whole tar blob.
	Digest digest.Digest
	// Digest represents the original OCI tar(.gz) blob.
	OriginalDigest *digest.Digest
	// ReaderAt holds the reader of whole tar blob.
	ReaderAt content.ReaderAt
}

type MergeOption struct {
	// WorkDir is used as the work directory during layer merge.
	WorkDir string
	// BuilderPath holds the path of `nydus-image` binary tool.
	BuilderPath string
	// FsVersion specifies nydus RAFS format version, possible
	// values: `5`, `6` (EROFS-compatible), default is `6`.
	FsVersion string
	// ChunkDictPath holds the bootstrap path of chunk dict image.
	ChunkDictPath string
	// ParentBootstrapPath holds the bootstrap path of parent image.
	ParentBootstrapPath string
	// PrefetchPatterns holds file path pattern list want to prefetch.
	PrefetchPatterns string
	// WithTar puts bootstrap into a tar stream (no gzip).
	WithTar bool
	// OCI converts docker media types to OCI media types.
	OCI bool
	// OCIRef enables converting OCI tar(.gz) blob to nydus referenced blob.
	OCIRef bool
	// WithReferrer associates a reference to the original OCI manifest.
	// See the `subject` field description in
	// https://github.com/opencontainers/image-spec/blob/main/manifest.md#image-manifest-property-descriptions
	//
	// With this association, we can track all nydus images associated with
	// an OCI image. For example, in Harbor we can cascade to show nydus
	// images linked to an OCI image, deleting the OCI image can also delete
	// the corresponding nydus images. At runtime, nydus snapshotter can also
	// automatically upgrade an OCI image run to nydus image.
	WithReferrer bool
	// Backend uploads blobs generated by nydus-image builder to a backend storage.
	Backend Backend
	// Timeout cancels execution once exceed the specified time.
	Timeout *time.Duration
	// Encrypt encrypts the bootstrap layer if it's specified.
	Encrypt Encrypter
	// AppendFiles specifies the files that need to be appended to the bootstrap layer.
	AppendFiles []File
}

type PackOption struct {
	// WorkDir is used as the work directory during layer pack.
	WorkDir string
	// BuilderPath holds the path of `nydus-image` binary tool.
	BuilderPath string
	// FsVersion specifies nydus RAFS format version, possible
	// values: `5`, `6` (EROFS-compatible), default is `6`.
	FsVersion string
	// ChunkDictPath holds the bootstrap path of chunk dict image.
	ChunkDictPath string
	// PrefetchPatterns holds file path pattern list want to prefetch.
	PrefetchPatterns string
	// Compressor specifies nydus blob compression algorithm.
	Compressor string
	// OCIRef enables converting OCI tar(.gz) blob to nydus referenced blob.
	OCIRef bool
	// AlignedChunk aligns uncompressed data chunks to 4K, only for RAFS V5.
	AlignedChunk bool
	// ChunkSize sets the size of data chunks, must be power of two and between 0x1000-0x1000000.
	ChunkSize string
	// BacthSize sets the size of batch data chunks, must be power of two and between 0x1000-0x1000000 or zero.
	BatchSize string
	// Backend uploads blobs generated by nydus-image builder to a backend storage.
	Backend Backend
	// Timeout cancels execution once exceed the specified time.
	Timeout *time.Duration
	// Whether the generated Nydus blobs should be encrypted.
	Encrypt bool
	// contains filtered or unexported fields
}

type TOCEntry struct {
	// Feature flags of entry
	Flags     uint32
	Reserved1 uint32
	// Name of entry data
	Name [16]byte
	// Sha256 of uncompressed entry data
	UncompressedDigest [32]byte
	// Offset of compressed entry data
	CompressedOffset uint64
	// Size of compressed entry data
	CompressedSize uint64
	// Size of uncompressed entry data
	UncompressedSize uint64
	Reserved2        [44]byte
}

type UnpackOption struct {
	// WorkDir is used as the work directory during layer unpack.
	WorkDir string
	// BuilderPath holds the path of `nydus-image` binary tool.
	BuilderPath string
	// Timeout cancels execution once exceed the specified time.
	Timeout *time.Duration
	// Stream enables streaming mode, which doesn't unpack the blob data to disk,
	// but setup a http server to serve the blob data.
	Stream bool
}