package main

import (
	"fmt"
	"image"
	"image/jpeg"
	"image/png"
	"os"
	"strings"

	"github.com/rwcarlsen/goexif/exif"
	"github.com/rwcarlsen/goexif/tiff"
	"golang.org/x/image/bmp"
	"golang.org/x/image/webp"
)

func CheckFilePath(name string) string {
	if _, err := os.Stat(name); err == nil {
		return name
	}
	panic(fmt.Errorf("%v does not exist in any directory which contains in $GOPATH", name))
}

func ReadIMG(name string) (img image.Image, orientation *tiff.Tag, err error) {
	file, err := os.Open(CheckFilePath(name))
	if err != nil {
		return nil, nil, err
	}

	x, err := exif.Decode(file)
	if err != nil {
		return nil, nil, err
	}

	orientation, err = x.Get(exif.Orientation)
	if err != nil {
		return nil, nil, err
	}

	file, err = os.Open(CheckFilePath(name))
	if err != nil {
		return nil, nil, err
	}

	parts := strings.Split(name, ".")
	switch strings.ToLower(parts[len(parts)-1]) {
	case "jpg":
		fallthrough
	case "jpeg":
		img, err = jpeg.Decode(file)
	case "png":
		img, err = png.Decode(file)
	case "bmp":
		img, err = bmp.Decode(file)
	case "webp":
		img, err = webp.Decode(file)
	}
	if err != nil {
		return nil, nil, err
	}

	return img, orientation, nil
}