package storage

import (
	"encoding/json"
	"path"
	"strings"

	"github.com/notaryproject/notation-go"
	godigest "github.com/opencontainers/go-digest"
	ispec "github.com/opencontainers/image-spec/specs-go/v1"
	artifactspec "github.com/oras-project/artifacts-spec/specs-go/v1"
	"github.com/rs/zerolog"
	"github.com/sigstore/cosign/pkg/oci/remote"
	zerr "zotregistry.io/zot/errors"
)

const (
	// BlobUploadDir defines the upload directory for blob uploads.
	BlobUploadDir = ".uploads"
	SchemaVersion = 2
	RLOCK         = "RLock"
	RWLOCK        = "RWLock"
)

func GetTagsByIndex(index ispec.Index) []string {
	tags := make([]string, 0)

	for _, manifest := range index.Manifests {
		v, ok := manifest.Annotations[ispec.AnnotationRefName]
		if ok {
			tags = append(tags, v)
		}
	}

	return tags
}

func GetManifestDescByReference(index ispec.Index, reference string) (ispec.Descriptor, bool) {
	var manifestDesc ispec.Descriptor

	for _, manifest := range index.Manifests {
		if reference == manifest.Digest.String() {
			return manifest, true
		}

		v, ok := manifest.Annotations[ispec.AnnotationRefName]
		if ok && v == reference {
			return manifest, true
		}
	}

	return manifestDesc, false
}

func ValidateManifest(imgStore ImageStore, repo, reference, mediaType string, body []byte,
	log zerolog.Logger,
) (string, error) {
	// validate the manifest
	if !IsSupportedMediaType(mediaType) {
		log.Debug().Interface("actual", mediaType).
			Msg("bad manifest media type")

		return "", zerr.ErrBadManifest
	}

	if len(body) == 0 {
		log.Debug().Int("len", len(body)).Msg("invalid body length")

		return "", zerr.ErrBadManifest
	}

	if mediaType == ispec.MediaTypeImageManifest {
		var manifest ispec.Manifest
		if err := json.Unmarshal(body, &manifest); err != nil {
			log.Error().Err(err).Msg("unable to unmarshal JSON")

			return "", zerr.ErrBadManifest
		}

		if manifest.Config.MediaType == ispec.MediaTypeImageConfig {
			digest, err := validateOCIManifest(imgStore, repo, reference, &manifest, log)
			if err != nil {
				log.Error().Err(err).Msg("invalid oci image manifest")

				return digest, err
			}
		}
	} else if mediaType == artifactspec.MediaTypeArtifactManifest {
		var m notation.Descriptor
		if err := json.Unmarshal(body, &m); err != nil {
			log.Error().Err(err).Msg("unable to unmarshal JSON")

			return "", zerr.ErrBadManifest
		}
	}

	return "", nil
}

func validateOCIManifest(imgStore ImageStore, repo, reference string, manifest *ispec.Manifest, //nolint:unparam
	log zerolog.Logger,
) (string, error) {
	if manifest.SchemaVersion != SchemaVersion {
		log.Error().Int("SchemaVersion", manifest.SchemaVersion).Msg("invalid manifest")

		return "", zerr.ErrBadManifest
	}

	// validate image config
	config := manifest.Config

	blobFile, _, err := imgStore.GetBlob(repo, config.Digest.String(), "")
	if err != nil {
		return config.Digest.String(), zerr.ErrBlobNotFound
	}

	defer blobFile.Close()

	dec := json.NewDecoder(blobFile)

	var cspec ispec.Image
	if err := dec.Decode(&cspec); err != nil {
		return "", zerr.ErrBadManifest
	}

	// validate the layers
	for _, l := range manifest.Layers {
		blobFile, _, err := imgStore.GetBlob(repo, l.Digest.String(), "")
		if err != nil {
			return l.Digest.String(), zerr.ErrBlobNotFound
		}

		defer blobFile.Close()
	}

	return "", nil
}

func GetAndValidateRequestDigest(body []byte, digest string, log zerolog.Logger) (godigest.Digest, error) {
	bodyDigest := godigest.FromBytes(body)

	d, err := godigest.Parse(digest)
	if err == nil {
		if d.String() != bodyDigest.String() {
			log.Error().Str("actual", bodyDigest.String()).Str("expected", d.String()).
				Msg("manifest digest is not valid")

			return "", zerr.ErrBadManifest
		}
	}

	return bodyDigest, err
}

/*
	CheckIfIndexNeedsUpdate verifies if an index needs to be updated given a new manifest descriptor.

Returns whether or not index needs update, in the latter case it will also return the previous digest.
*/
func CheckIfIndexNeedsUpdate(index *ispec.Index, desc *ispec.Descriptor,
	log zerolog.Logger,
) (bool, godigest.Digest, error) {
	var oldDgst godigest.Digest

	var reference string

	tag, ok := desc.Annotations[ispec.AnnotationRefName]
	if ok {
		reference = tag
	} else {
		reference = desc.Digest.String()
	}

	updateIndex := true

	for midx, manifest := range index.Manifests {
		manifest := manifest
		if reference == manifest.Digest.String() {
			// nothing changed, so don't update
			desc = &manifest
			updateIndex = false

			break
		}

		v, ok := manifest.Annotations[ispec.AnnotationRefName]
		if ok && v == reference {
			if manifest.Digest.String() == desc.Digest.String() {
				// nothing changed, so don't update
				desc = &manifest
				updateIndex = false

				break
			}

			// manifest contents have changed for the same tag,
			// so update index.json descriptor
			log.Info().
				Int64("old size", manifest.Size).
				Int64("new size", desc.Size).
				Str("old digest", manifest.Digest.String()).
				Str("new digest", desc.Digest.String()).
				Str("old mediaType", manifest.MediaType).
				Str("new mediaType", desc.MediaType).
				Msg("updating existing tag with new manifest contents")

			// changing media-type is disallowed!
			if manifest.MediaType != desc.MediaType {
				err := zerr.ErrBadManifest
				log.Error().Err(err).
					Str("old mediaType", manifest.MediaType).
					Str("new mediaType", desc.MediaType).Msg("cannot change media-type")

				return false, "", err
			}

			oldDesc := *desc

			desc = &manifest
			oldDgst = manifest.Digest
			desc.Size = oldDesc.Size
			desc.Digest = oldDesc.Digest

			index.Manifests = append(index.Manifests[:midx], index.Manifests[midx+1:]...)

			break
		}
	}

	return updateIndex, oldDgst, nil
}

func GetIndex(imgStore ImageStore, repo string, log zerolog.Logger) (ispec.Index, error) {
	var index ispec.Index

	buf, err := imgStore.GetIndexContent(repo)
	if err != nil {
		return index, err
	}

	if err := json.Unmarshal(buf, &index); err != nil {
		log.Error().Err(err).Str("dir", path.Join(imgStore.RootDir(), repo)).Msg("invalid JSON")

		return index, zerr.ErrRepoBadVersion
	}

	return index, nil
}

func RemoveManifestDescByReference(index *ispec.Index, reference string) (ispec.Descriptor, bool) {
	var removedManifest ispec.Descriptor

	var found bool

	var outIndex ispec.Index

	for _, manifest := range index.Manifests {
		tag, ok := manifest.Annotations[ispec.AnnotationRefName]
		if ok && tag == reference {
			removedManifest = manifest
			found = true

			continue
		} else if reference == manifest.Digest.String() {
			removedManifest = manifest
			found = true

			continue
		}

		outIndex.Manifests = append(outIndex.Manifests, manifest)
	}

	index.Manifests = outIndex.Manifests

	return removedManifest, found
}

/*
	additionally, unmarshal an image index and for all manifests in that

index, ensure that they do not have a name or they are not in other
manifest indexes else GC can never clean them.
*/
func UpdateIndexWithPrunedImageManifests(imgStore ImageStore, index *ispec.Index, repo string,
	desc ispec.Descriptor, oldDgst godigest.Digest, log zerolog.Logger,
) error {
	if (desc.MediaType == ispec.MediaTypeImageIndex) && (oldDgst != "") {
		otherImgIndexes := []ispec.Descriptor{}

		for _, manifest := range index.Manifests {
			if manifest.MediaType == ispec.MediaTypeImageIndex {
				otherImgIndexes = append(otherImgIndexes, manifest)
			}
		}

		otherImgIndexes = append(otherImgIndexes, desc)

		prunedManifests, err := PruneImageManifestsFromIndex(imgStore, repo, oldDgst, *index, otherImgIndexes, log)
		if err != nil {
			return err
		}

		index.Manifests = prunedManifests
	}

	return nil
}

/*
*
before an image index manifest is pushed to a repo, its constituent manifests
are pushed first, so when updating/removing this image index manifest, we also
need to determine if there are other image index manifests which refer to the
same constitutent manifests so that they can be garbage-collected correctly

pruneImageManifestsFromIndex is a helper routine to achieve this.
*/
func PruneImageManifestsFromIndex(imgStore ImageStore, repo string, digest godigest.Digest, //nolint:gocyclo
	outIndex ispec.Index, otherImgIndexes []ispec.Descriptor, log zerolog.Logger,
) ([]ispec.Descriptor, error) {
	dir := path.Join(imgStore.RootDir(), repo)

	indexPath := path.Join(dir, "blobs", digest.Algorithm().String(), digest.Encoded())

	buf, err := imgStore.GetBlobContent(repo, digest.String())
	if err != nil {
		return nil, err
	}

	var imgIndex ispec.Index
	if err := json.Unmarshal(buf, &imgIndex); err != nil {
		log.Error().Err(err).Str("path", indexPath).Msg("invalid JSON")

		return nil, err
	}

	inUse := map[string]uint{}

	for _, manifest := range imgIndex.Manifests {
		inUse[manifest.Digest.Encoded()]++
	}

	for _, otherIndex := range otherImgIndexes {
		buf, err := imgStore.GetBlobContent(repo, otherIndex.Digest.String())
		if err != nil {
			return nil, err
		}

		indexPath := path.Join(imgStore.RootDir(), repo, "blobs",
			otherIndex.Digest.Algorithm().String(), otherIndex.Digest.Encoded())

		var oindex ispec.Index
		if err := json.Unmarshal(buf, &oindex); err != nil {
			log.Error().Err(err).Str("path", indexPath).Msg("invalid JSON")

			return nil, err
		}

		for _, omanifest := range oindex.Manifests {
			_, ok := inUse[omanifest.Digest.Encoded()]
			if ok {
				inUse[omanifest.Digest.Encoded()]++
			}
		}
	}

	prunedManifests := []ispec.Descriptor{}

	// for all manifests in the index, skip those that either have a tag or
	// are used in other imgIndexes
	for _, outManifest := range outIndex.Manifests {
		if outManifest.MediaType != ispec.MediaTypeImageManifest {
			prunedManifests = append(prunedManifests, outManifest)

			continue
		}

		_, ok := outManifest.Annotations[ispec.AnnotationRefName]
		if ok {
			prunedManifests = append(prunedManifests, outManifest)

			continue
		}

		count, ok := inUse[outManifest.Digest.Encoded()]
		if !ok {
			prunedManifests = append(prunedManifests, outManifest)

			continue
		}

		if count != 1 {
			// this manifest is in use in other image indexes
			prunedManifests = append(prunedManifests, outManifest)

			continue
		}
	}

	return prunedManifests, nil
}

func ApplyLinter(imgStore ImageStore, linter Lint, repo string, manifestDesc ispec.Descriptor) (bool, error) {
	pass := true

	if linter != nil {
		tag := manifestDesc.Annotations[ispec.AnnotationRefName]
		// apply linter only on images, not signatures
		if manifestDesc.MediaType == ispec.MediaTypeImageManifest &&
			// check that image manifest is not cosign signature
			!strings.HasPrefix(tag, "sha256-") &&
			!strings.HasSuffix(tag, remote.SignatureTagSuffix) {
			// lint new index with new manifest before writing to disk
			pass, err := linter.Lint(repo, manifestDesc.Digest, imgStore)
			if err != nil {
				return false, err
			}

			if !pass {
				return false, zerr.ErrImageLintAnnotations
			}
		}
	}

	return pass, nil
}

func IsSupportedMediaType(mediaType string) bool {
	return mediaType == ispec.MediaTypeImageIndex ||
		mediaType == ispec.MediaTypeImageManifest ||
		mediaType == artifactspec.MediaTypeArtifactManifest
}