package photos

import (
	"bytes"
	"image"
	"time"

	"github.com/disintegration/imaging"
	"github.com/gen2brain/webp"
	"github.com/rwcarlsen/goexif/exif"
)

type ImageMeta struct {
	Width     int
	Height    int
	MimeType  string
	TakenAt   *time.Time
	Latitude  *float64
	Longitude *float64
	Thumb     []byte
	Preview   []byte
}

func inspect(data []byte) (width, height int, ok bool) {
	cfg, _, err := image.DecodeConfig(bytes.NewReader(data))
	if err != nil {
		return 0, 0, false
	}
	return cfg.Width, cfg.Height, true
}

func extractEXIF(data []byte) (taken *time.Time, lat, lon *float64) {
	x, err := exif.Decode(bytes.NewReader(data))
	if err != nil {
		return nil, nil, nil
	}
	if dt, err := x.Get(exif.DateTimeOriginal); err == nil {
		if s, err := dt.StringVal(); err == nil {
			if t, err := time.Parse("2006:01:02 15:04:05", s); err == nil {
				utc := t.UTC()
				taken = &utc
			}
		}
	}
	if la, lo, err := x.LatLong(); err == nil {
		lat, lon = &la, &lo
	}
	return taken, lat, lon
}

func buildVariants(data []byte) (thumb, preview []byte, err error) {
	img, err := imaging.Decode(bytes.NewReader(data), imaging.AutoOrientation(true))
	if err != nil {
		return nil, nil, err
	}
	thumbImg := imaging.Fit(img, 200, 200, imaging.Lanczos)
	previewImg := imaging.Fit(img, 1200, 1200, imaging.Lanczos)

	opts := webp.Options{Quality: 82}
	var thumbBuf bytes.Buffer
	if err := webp.Encode(&thumbBuf, thumbImg, opts); err != nil {
		return nil, nil, err
	}
	var previewBuf bytes.Buffer
	if err := webp.Encode(&previewBuf, previewImg, opts); err != nil {
		return nil, nil, err
	}
	return thumbBuf.Bytes(), previewBuf.Bytes(), nil
}