package resize

import (
	"bytes"
	"image"
	"image/color"
	"image/jpeg"
	"testing"
)

func createTestImage() []byte {
	img := image.NewRGBA(image.Rect(0, 0, 100, 100))
	for x := 0; x < 100; x++ {
		for y := 0; y < 100; y++ {
			img.Set(x, y, color.RGBA{uint8(x), uint8(y), 255, 255})
		}
	}
	var buf bytes.Buffer
	_ = jpeg.Encode(&buf, img, nil)
	return buf.Bytes()
}

func TestShrink_Success(t *testing.T) {
	testImage := createTestImage()
	result, err := Shrink(string(testImage), 50, 80)
	if err != nil {
		t.Fatalf("expected no error, got %v", err)
	}
	if len(result) == 0 {
		t.Fatalf("expected non-empty result, got empty string")
	}
}

func TestShrink_InvalidImage(t *testing.T) {
	invalidImage := "not-an-image"
	_, err := Shrink(invalidImage, 50, 80)
	if err == nil {
		t.Fatalf("expected an error for invalid image input, got nil")
	}
}

func TestShrink_InvalidQuality(t *testing.T) {
	testImage := createTestImage()
	_, err := Shrink(string(testImage), 50, -10)
	if err == nil {
		t.Fatalf("expected an error for invalid quality, got nil")
	}
}