// Package common ...
package common

import (
	"encoding/json"
	"io/ioutil"
	"os"
	"path"
	"strings"
	"time"

	"github.com/anuvu/zot/errors"
	"github.com/anuvu/zot/pkg/log"
	v1 "github.com/google/go-containerregistry/pkg/v1"
	"github.com/google/go-containerregistry/pkg/v1/types"
	godigest "github.com/opencontainers/go-digest"
	ispec "github.com/opencontainers/image-spec/specs-go/v1"
)

// OciLayoutInfo ...
type OciLayoutUtils struct {
	Log log.Logger
}

// NewOciLayoutUtils initializes a new OciLayoutUtils object.
func NewOciLayoutUtils(log log.Logger) *OciLayoutUtils {
	return &OciLayoutUtils{Log: log}
}

// Below method will return image path including root dir, root dir is determined by splitting.

func (olu OciLayoutUtils) GetImageManifests(imagePath string) ([]ispec.Descriptor, error) {
	buf, err := ioutil.ReadFile(path.Join(imagePath, "index.json"))

	if err != nil {
		if os.IsNotExist(err) {
			olu.Log.Error().Err(err).Msg("index.json doesn't exist")

			return nil, errors.ErrRepoNotFound
		}

		olu.Log.Error().Err(err).Msg("unable to open index.json")

		return nil, errors.ErrRepoNotFound
	}

	var index ispec.Index

	if err := json.Unmarshal(buf, &index); err != nil {
		olu.Log.Error().Err(err).Str("dir", imagePath).Msg("invalid JSON")
		return nil, errors.ErrRepoNotFound
	}

	return index.Manifests, nil
}

func (olu OciLayoutUtils) GetImageBlobManifest(imageDir string, digest godigest.Digest) (v1.Manifest, error) {
	var blobIndex v1.Manifest

	blobBuf, err := ioutil.ReadFile(path.Join(imageDir, "blobs", digest.Algorithm().String(), digest.Encoded()))
	if err != nil {
		olu.Log.Error().Err(err).Msg("unable to open image metadata file")

		return blobIndex, err
	}

	if err := json.Unmarshal(blobBuf, &blobIndex); err != nil {
		olu.Log.Error().Err(err).Msg("unable to marshal blob index")

		return blobIndex, err
	}

	return blobIndex, nil
}

func (olu OciLayoutUtils) GetImageInfo(imageDir string, hash v1.Hash) (ispec.Image, error) {
	var imageInfo ispec.Image

	blobBuf, err := ioutil.ReadFile(path.Join(imageDir, "blobs", hash.Algorithm, hash.Hex))
	if err != nil {
		olu.Log.Error().Err(err).Msg("unable to open image layers file")

		return imageInfo, err
	}

	if err := json.Unmarshal(blobBuf, &imageInfo); err != nil {
		olu.Log.Error().Err(err).Msg("unable to marshal blob index")

		return imageInfo, err
	}

	return imageInfo, err
}

func (olu OciLayoutUtils) IsValidImageFormat(imagePath string) (bool, error) {
	imageDir, inputTag := GetImageDirAndTag(imagePath)

	if !DirExists(imageDir) {
		olu.Log.Error().Msg("image directory doesn't exist")

		return false, errors.ErrRepoNotFound
	}

	manifests, err := olu.GetImageManifests(imageDir)

	if err != nil {
		return false, err
	}

	for _, m := range manifests {
		tag, ok := m.Annotations[ispec.AnnotationRefName]

		if ok && inputTag != "" && tag != inputTag {
			continue
		}

		blobManifest, err := olu.GetImageBlobManifest(imageDir, m.Digest)
		if err != nil {
			return false, err
		}

		imageLayers := blobManifest.Layers

		for _, imageLayer := range imageLayers {
			switch imageLayer.MediaType {
			case types.OCILayer, types.DockerLayer:
				return true, nil

			default:
				olu.Log.Debug().Msg("image media type not supported for scanning")
				return false, errors.ErrScanNotSupported
			}
		}
	}

	return false, nil
}

// GetImageTagsWithTimestamp returns a list of image tags with timestamp available in the specified repository.
func (olu OciLayoutUtils) GetImageTagsWithTimestamp(repo string) ([]TagInfo, error) {
	tagsInfo := make([]TagInfo, 0)

	manifests, err := olu.GetImageManifests(repo)
	if err != nil {
		olu.Log.Error().Err(err).Msg("unable to read image manifests")

		return tagsInfo, err
	}

	for _, manifest := range manifests {
		digest := manifest.Digest

		v, ok := manifest.Annotations[ispec.AnnotationRefName]
		if ok {
			imageBlobManifest, err := olu.GetImageBlobManifest(repo, digest)
			if err != nil {
				olu.Log.Error().Err(err).Msg("unable to read image blob manifest")

				return tagsInfo, err
			}

			imageInfo, err := olu.GetImageInfo(repo, imageBlobManifest.Config.Digest)
			if err != nil {
				olu.Log.Error().Err(err).Msg("unable to read image info")

				return tagsInfo, err
			}

			var timeStamp time.Time

			if len(imageInfo.History) != 0 {
				timeStamp = *imageInfo.History[0].Created
			} else {
				timeStamp = time.Time{}
			}

			tagsInfo = append(tagsInfo, TagInfo{Name: v, Timestamp: timeStamp, Digest: digest.String()})
		}
	}

	return tagsInfo, nil
}

func DirExists(d string) bool {
	fi, err := os.Stat(d)
	if err != nil && os.IsNotExist(err) {
		return false
	}

	return fi.IsDir()
}

func GetImageDirAndTag(imageName string) (string, string) {
	var imageDir string

	var imageTag string

	if strings.Contains(imageName, ":") {
		splitImageName := strings.Split(imageName, ":")
		imageDir = splitImageName[0]
		imageTag = splitImageName[1]
	} else {
		imageDir = imageName
	}

	return imageDir, imageTag
}