package storage

import (
	"fmt"
	"strings"

	"github.com/docker/distribution"
	ctxu "github.com/docker/distribution/context"
	"github.com/docker/distribution/digest"
	"github.com/docker/distribution/manifest"
	"github.com/docker/libtrust"
)

// ErrUnknownRepository is returned if the named repository is not known by
// the registry.
type ErrUnknownRepository struct {
	Name string
}

func (err ErrUnknownRepository) Error() string {
	return fmt.Sprintf("unknown respository name=%s", err.Name)
}

// ErrUnknownManifest is returned if the manifest is not known by the
// registry.
type ErrUnknownManifest struct {
	Name string
	Tag  string
}

func (err ErrUnknownManifest) Error() string {
	return fmt.Sprintf("unknown manifest name=%s tag=%s", err.Name, err.Tag)
}

// ErrUnknownManifestRevision is returned when a manifest cannot be found by
// revision within a repository.
type ErrUnknownManifestRevision struct {
	Name     string
	Revision digest.Digest
}

func (err ErrUnknownManifestRevision) Error() string {
	return fmt.Sprintf("unknown manifest name=%s revision=%s", err.Name, err.Revision)
}

// ErrManifestUnverified is returned when the registry is unable to verify
// the manifest.
type ErrManifestUnverified struct{}

func (ErrManifestUnverified) Error() string {
	return fmt.Sprintf("unverified manifest")
}

// ErrManifestVerification provides a type to collect errors encountered
// during manifest verification. Currently, it accepts errors of all types,
// but it may be narrowed to those involving manifest verification.
type ErrManifestVerification []error

func (errs ErrManifestVerification) Error() string {
	var parts []string
	for _, err := range errs {
		parts = append(parts, err.Error())
	}

	return fmt.Sprintf("errors verifying manifest: %v", strings.Join(parts, ","))
}

type manifestStore struct {
	repository *repository

	revisionStore *revisionStore
	tagStore      *tagStore
}

var _ distribution.ManifestService = &manifestStore{}

// func (ms *manifestStore) Repository() Repository {
// 	return ms.repository
// }

func (ms *manifestStore) Tags() ([]string, error) {
	ctxu.GetLogger(ms.repository.ctx).Debug("(*manifestStore).Tags")
	return ms.tagStore.tags()
}

func (ms *manifestStore) Exists(tag string) (bool, error) {
	ctxu.GetLogger(ms.repository.ctx).Debug("(*manifestStore).Exists")
	return ms.tagStore.exists(tag)
}

func (ms *manifestStore) Get(tag string) (*manifest.SignedManifest, error) {
	ctxu.GetLogger(ms.repository.ctx).Debug("(*manifestStore).Get")
	dgst, err := ms.tagStore.resolve(tag)
	if err != nil {
		return nil, err
	}

	return ms.revisionStore.get(dgst)
}

func (ms *manifestStore) Put(tag string, manifest *manifest.SignedManifest) error {
	ctxu.GetLogger(ms.repository.ctx).Debug("(*manifestStore).Put")

	// TODO(stevvooe): Add check here to see if the revision is already
	// present in the repository. If it is, we should merge the signatures, do
	// a shallow verify (or a full one, doesn't matter) and return an error
	// indicating what happened.

	// Verify the manifest.
	if err := ms.verifyManifest(tag, manifest); err != nil {
		return err
	}

	// Store the revision of the manifest
	revision, err := ms.revisionStore.put(manifest)
	if err != nil {
		return err
	}

	// Now, tag the manifest
	return ms.tagStore.tag(tag, revision)
}

// Delete removes all revisions of the given tag. We may want to change these
// semantics in the future, but this will maintain consistency. The underlying
// blobs are left alone.
func (ms *manifestStore) Delete(tag string) error {
	ctxu.GetLogger(ms.repository.ctx).Debug("(*manifestStore).Delete")

	revisions, err := ms.tagStore.revisions(tag)
	if err != nil {
		return err
	}

	for _, revision := range revisions {
		if err := ms.revisionStore.delete(revision); err != nil {
			return err
		}
	}

	return ms.tagStore.delete(tag)
}

// verifyManifest ensures that the manifest content is valid from the
// perspective of the registry. It ensures that the name and tag match and
// that the signature is valid for the enclosed payload. As a policy, the
// registry only tries to store valid content, leaving trust policies of that
// content up to consumers.
func (ms *manifestStore) verifyManifest(tag string, mnfst *manifest.SignedManifest) error {
	var errs ErrManifestVerification
	if mnfst.Name != ms.repository.Name() {
		// TODO(stevvooe): This needs to be an exported error
		errs = append(errs, fmt.Errorf("repository name does not match manifest name"))
	}

	if mnfst.Tag != tag {
		// TODO(stevvooe): This needs to be an exported error.
		errs = append(errs, fmt.Errorf("tag does not match manifest tag"))
	}

	if _, err := manifest.Verify(mnfst); err != nil {
		switch err {
		case libtrust.ErrMissingSignatureKey, libtrust.ErrInvalidJSONContent, libtrust.ErrMissingSignatureKey:
			errs = append(errs, ErrManifestUnverified{})
		default:
			if err.Error() == "invalid signature" { // TODO(stevvooe): This should be exported by libtrust
				errs = append(errs, ErrManifestUnverified{})
			} else {
				errs = append(errs, err)
			}
		}
	}

	for _, fsLayer := range mnfst.FSLayers {
		exists, err := ms.repository.Layers().Exists(fsLayer.BlobSum)
		if err != nil {
			errs = append(errs, err)
		}

		if !exists {
			errs = append(errs, distribution.ErrUnknownLayer{FSLayer: fsLayer})
		}
	}

	if len(errs) != 0 {
		// TODO(stevvooe): These need to be recoverable by a caller.
		return errs
	}

	return nil
}