package image

import (
	"bytes"
	"github.com/anthonynsimon/bild/transform"
	"image"
	"image/jpeg"
	"io"
)

func ResizeImage(imageBytes []byte, minWidth, minHeight int) ([]byte, error) {
	img, _, err := image.Decode(bytes.NewReader(imageBytes))
	if err != nil {
		return nil, err
	}
	var buffer bytes.Buffer
	writer := io.Writer(&buffer)

	rX, rY := Resize(minWidth, minHeight, img.Bounds().Dx(), img.Bounds().Dy())

	img = transform.Resize(img, rX, rY, transform.Gaussian)

	if err = jpeg.Encode(writer, img, nil); err != nil {
		return nil, err
	}
	return buffer.Bytes(), nil
}

func Resize(minX, minY, x, y int) (int, int) {
	return resize(float32(minX), float32(minY), float32(x), float32(y))
}

func resize(minX, minY, x, y float32) (int, int) {
	if x <= minX && y <= minY {
		return int(x), int(y)
	}

	// try by width
	rX := minX
	rY := y * (rX / x)
	if rX >= minX && rY >= minY && rX <= x && rY <= y {
		return int(rX), int(rY)
	}
	// try by height
	rY = minY
	rX = x * (rY / y)
	if rX >= minX && rY >= minY && rX <= x && rY <= y {
		return int(rX), int(rY)
	}

	return int(x), int(y)
}