package thumb

import (
	"fmt"
	"image"
	"io"
	"os"
	"path/filepath"

	"github.com/disintegration/imaging"
	"github.com/mandykoh/prism/meta"
	"github.com/mandykoh/prism/meta/autometa"
	"github.com/photoprism/photoprism/pkg/clean"
	"github.com/photoprism/photoprism/pkg/colors"
)

// decodeImage opens an image and decodes its color metadata.
func decodeImage(reader io.ReadSeeker, logName string) (metaData *meta.Data, img image.Image, err error) {
	// Read color metadata.
	metaData, imgReader, err := autometa.Load(reader)

	if err == nil {
		img, err = imaging.Decode(imgReader)
		return metaData, img, err
	}

	// Log color metadata read error.
	log.Infof("thumb: %s in %s (read color metadata)", err, logName)

	// Seek to the file start in order to avoid decoding errors,
	// see https://github.com/photoprism/photoprism/issues/3843
	if _, err = reader.Seek(0, io.SeekStart); err != nil {
		log.Errorf("thumb: %s in %s (seek to file start)", err, logName)
	}

	// Decode image file.
	img, err = imaging.Decode(reader)

	return metaData, img, err
}

// OpenJpeg loads a JPEG image from disk, rotates it, and converts the color profile if necessary.
func OpenJpeg(fileName string, orientation int) (image.Image, error) {
	if fileName == "" {
		return nil, fmt.Errorf("filename missing")
	}

	logName := clean.Log(filepath.Base(fileName))

	// Open file.
	fileReader, err := os.Open(fileName)
	if err != nil {
		return nil, err
	}
	defer fileReader.Close()

	// Reset file offset.
	// see https://github.com/golang/go/issues/45902#issuecomment-1007953723
	if _, err := fileReader.Seek(0, 0); err != nil {
		return nil, fmt.Errorf("%s on seek", err)
	}

	// Decode image incl color metadata.
	md, img, err := decodeImage(fileReader, logName)

	// Ok?
	if err != nil {
		return nil, fmt.Errorf("%s while decoding", err)
	}

	// Read ICC profile and convert colors if possible.
	if md != nil {
		if iccProfile, err := md.ICCProfile(); err != nil || iccProfile == nil {
			// Do nothing.
			log.Tracef("thumb: %s has no color profile", logName)
		} else if profile, err := iccProfile.Description(); err == nil && profile != "" {
			log.Tracef("thumb: %s has color profile %s", logName, clean.Log(profile))
			switch {
			case colors.ProfileDisplayP3.Equal(profile):
				img = colors.ToSRGB(img, colors.ProfileDisplayP3)
			}
		}
	}

	// Adjust orientation.
	if orientation > 1 {
		img = Rotate(img, orientation)
	}

	return img, nil
}