package repocli

import (
	"bytes"
	"context"
	"errors"
	"io"
	"os"
	"path/filepath"

	ocidigest "github.com/opencontainers/go-digest"
	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
)

type Imageer interface {
	WriteManifest(mime string, manifest []byte) error
	ReadManifest(digest string) (bool, string, []byte, error)
	WriteBlob(digest string, reader io.Reader) error
	ReadBlob(digest string, writer io.Writer) error
}

type Imager struct {
	index ocispec.Index
	place string
}

func NewImager(place string) *Imager {
	imager := &Imager{
		index: ocispec.Index{
			MediaType: MediaTypeOIIv1,
			Manifests: make([]ocispec.Descriptor, 0),
		},
		place: place,
	}
	//imager.SchemaVersion = 2
	return imager
}

func (ima *Imager) WriteManifest(ctx context.Context, digest, mime string, payload []byte) error {
	var err error
	digestobj, err := ocidigest.Parse(digest)
	if err != nil {
		return err
	}
	var subdir string
	switch digestobj.Algorithm() {
	case ocidigest.SHA256:
		subdir = "sha256"
	case ocidigest.SHA384:
		subdir = "sha384"
	case ocidigest.SHA512:
		subdir = "sha512"
	default:
		err := errors.New("Unknown digest type")
		return err
	}
	dir := filepath.Join(ima.place, subdir)
	err = os.MkdirAll(dir, 0750)
	if err != nil {
		return err
	}
	fpath := filepath.Join(dir, digestobj.Encoded())
	file, err := os.OpenFile(fpath, os.O_CREATE|os.O_WRONLY, 0640)
	if err != nil {
		return err
	}
	reader := bytes.NewReader(payload)
	size, err := io.Copy(file, reader)
	if size != int64(len(payload)) {
		err = errors.New("Mismatch sizes")
		return err
	}
	descr := ocispec.Descriptor{
		MediaType: mime,
		Digest:    digestobj,
		Size:      size,
	}
	ima.index.Manifests = append(ima.index.Manifests, descr)
	// TODO: flush index
	return err
}

func (ima *Imager) WriteLayer(ctx context.Context, digest string, size int64, reader io.Reader) error {
	var err error
	digestobj, err := ocidigest.Parse(digest)
	if err != nil {
		return err
	}
	var subdir string
	switch digestobj.Algorithm() {
	case ocidigest.SHA256:
		subdir = "sha256"
	case ocidigest.SHA384:
		subdir = "sha384"
	case ocidigest.SHA512:
		subdir = "sha512"
	default:
		err := errors.New("Unknown digest type")
		return err
	}
	dir := filepath.Join(ima.place, subdir)
	err = os.MkdirAll(dir, 0750)
	if err != nil {
		return err
	}
	fpath := filepath.Join(dir, digestobj.Encoded())
	file, err := os.OpenFile(fpath, os.O_CREATE|os.O_WRONLY, 0640)
	if err != nil {
		return err
	}
	verifier := digestobj.Verifier()
	mw := io.MultiWriter(verifier, file)
	recsize, err := io.Copy(mw, reader)
	if size != recsize {
		err = errors.New("Mismatch sizes")
		return err
	}
	if !verifier.Verified() {
		err = errors.New("Mismatch digests")
		return err
	}
	return err
}