package imaging

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

func compareNRGBA(img1, img2 *image.NRGBA, delta int) bool {
	if !img1.Rect.Eq(img2.Rect) {
		return false
	}

	if len(img1.Pix) != len(img2.Pix) {
		return false
	}

	for i := 0; i < len(img1.Pix); i++ {
		if absint(int(img1.Pix[i])-int(img2.Pix[i])) > delta {
			return false
		}
	}

	return true
}

func TestEncodeDecode(t *testing.T) {
	imgWithAlpha := image.NewNRGBA(image.Rect(0, 0, 3, 3))
	imgWithAlpha.Pix = []uint8{
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
		127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138,
		244, 245, 246, 247, 248, 249, 250, 252, 252, 253, 254, 255,
	}

	imgWithoutAlpha := image.NewNRGBA(image.Rect(0, 0, 3, 3))
	imgWithoutAlpha.Pix = []uint8{
		0, 1, 2, 255, 4, 5, 6, 255, 8, 9, 10, 255,
		127, 128, 129, 255, 131, 132, 133, 255, 135, 136, 137, 255,
		244, 245, 246, 255, 248, 249, 250, 255, 252, 253, 254, 255,
	}

	for _, format := range []Format{JPEG, PNG, GIF, BMP, TIFF} {
		img := imgWithoutAlpha
		if format == PNG {
			img = imgWithAlpha
		}

		buf := &bytes.Buffer{}
		err := Encode(buf, img, format)
		if err != nil {
			t.Errorf("fail encoding format %s", format)
			continue
		}

		img2, err := Decode(buf)
		if err != nil {
			t.Errorf("fail decoding format %s", format)
			continue
		}
		img2cloned := Clone(img2)

		delta := 0
		if format == JPEG {
			delta = 3
		} else if format == GIF {
			delta = 16
		}

		if !compareNRGBA(img, img2cloned, delta) {
			t.Errorf("test [DecodeEncode %s] failed: %#v %#v", format, img, img2cloned)
			continue
		}
	}

	buf := &bytes.Buffer{}
	err := Encode(buf, imgWithAlpha, JPEG)
	if err != nil {
		t.Errorf("failed encoding alpha to JPEG format %s", err)
	}

	buf = &bytes.Buffer{}
	err = Encode(buf, imgWithAlpha, Format(100))
	if err != ErrUnsupportedFormat {
		t.Errorf("expected ErrUnsupportedFormat")
	}

	buf = bytes.NewBuffer([]byte("bad data"))
	_, err = Decode(buf)
	if err == nil {
		t.Errorf("decoding bad data, expected error")
	}
}

func TestNew(t *testing.T) {
	td := []struct {
		desc      string
		w, h      int
		c         color.Color
		dstBounds image.Rectangle
		dstPix    []uint8
	}{
		{
			"New 1x1 black",
			1, 1,
			color.NRGBA{0, 0, 0, 0},
			image.Rect(0, 0, 1, 1),
			[]uint8{0x00, 0x00, 0x00, 0x00},
		},
		{
			"New 1x2 red",
			1, 2,
			color.NRGBA{255, 0, 0, 255},
			image.Rect(0, 0, 1, 2),
			[]uint8{0xff, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00, 0xff},
		},
		{
			"New 2x1 white",
			2, 1,
			color.NRGBA{255, 255, 255, 255},
			image.Rect(0, 0, 2, 1),
			[]uint8{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
		},
		{
			"New 0x0 white",
			0, 0,
			color.NRGBA{255, 255, 255, 255},
			image.Rect(0, 0, 0, 0),
			nil,
		},
	}

	for _, d := range td {
		got := New(d.w, d.h, d.c)
		want := image.NewNRGBA(d.dstBounds)
		want.Pix = d.dstPix
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestFormats(t *testing.T) {
	formatNames := map[Format]string{
		JPEG:       "JPEG",
		PNG:        "PNG",
		GIF:        "GIF",
		BMP:        "BMP",
		TIFF:       "TIFF",
		Format(-1): "Unsupported",
	}
	for format, name := range formatNames {
		got := format.String()
		if got != name {
			t.Errorf("test [Format names] failed: got %#v want %#v", got, name)
			continue
		}
	}
}