package useCases

import (
	"RenewCMS/internal/domain/image"
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	stdimage "image"
	"io"
	"path"

	_ "golang.org/x/image/webp"
	_ "image/jpeg"
	_ "image/png"
)

var extensionContentTypes = map[string]string{
	".png":  "image/png",
	".jpg":  "image/jpeg",
	".jpeg": "image/jpeg",
	".webp": "image/webp",
	".svg":  "image/svg+xml",
}

type BackfillImageMetadataUseCase struct {
	imageRepository image.Repository
	storage         image.Storage
}

func NewBackfillImageMetadataUseCase(imageRepository image.Repository, storage image.Storage) *BackfillImageMetadataUseCase {
	return &BackfillImageMetadataUseCase{imageRepository, storage}
}

func (u *BackfillImageMetadataUseCase) Run() error {
	pending, err := u.imageRepository.ListMissingMetadata()
	if err != nil {
		return err
	}
	for _, row := range pending {
		metadata, ok := u.readStoredImage(row.Path)
		if !ok {
			continue
		}
		if err := u.imageRepository.UpdateMetadata(row.ID, metadata); err != nil {
			return err
		}
	}
	return nil
}

func (u *BackfillImageMetadataUseCase) readStoredImage(storedPath string) (image.Metadata, bool) {
	fileName := image.StoredName(storedPath)
	contentType, known := extensionContentTypes[path.Ext(fileName)]
	if !known {
		return image.Metadata{}, false
	}

	data, err := u.read(fileName)
	if err != nil {
		return image.Metadata{}, false
	}

	width, height := 0, 0
	if contentType != "image/svg+xml" {
		config, _, err := stdimage.DecodeConfig(bytes.NewReader(data))
		if err != nil {
			return image.Metadata{}, false
		}
		width, height = config.Width, config.Height
	}

	checksum := sha256.Sum256(data)
	return image.Metadata{
		Filename:    fileName,
		Size:        int64(len(data)),
		ContentType: contentType,
		Width:       width,
		Height:      height,
		SHA256:      hex.EncodeToString(checksum[:]),
	}, true
}

func (u *BackfillImageMetadataUseCase) read(storedName string) ([]byte, error) {
	blob, err := u.storage.Open(storedName)
	if err != nil {
		return nil, err
	}
	defer blob.Content.Close()
	return io.ReadAll(blob.Content)
}