// Copyright 2016 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package ebiten_test

import (
	"errors"
	"image"
	"image/color"
	"image/draw"
	_ "image/png"
	"math"
	"os"
	"testing"

	. "github.com/hajimehoshi/ebiten"
)

func TestMain(m *testing.M) {
	code := 0
	// Run an Ebiten process so that (*Image).At is available.
	regularTermination := errors.New("regular termination")
	f := func(screen *Image) error {
		code = m.Run()
		return regularTermination
	}
	if err := Run(f, 320, 240, 1, "Test"); err != nil && err != regularTermination {
		panic(err)
	}
	os.Exit(code)
}

var ebitenImageBin = ""

func openImage(path string) (image.Image, error) {
	file, err := readFile(path)
	if err != nil {
		return nil, err
	}

	img, _, err := image.Decode(file)
	if err != nil {
		return nil, err
	}
	return img, nil
}

func openEbitenImage(path string) (*Image, image.Image, error) {
	img, err := openImage(path)
	if err != nil {
		return nil, nil, err
	}

	eimg, err := NewImageFromImage(img, FilterNearest)
	if err != nil {
		return nil, nil, err
	}
	return eimg, img, nil
}

func diff(x, y uint8) uint8 {
	if x <= y {
		return y - x
	}
	return x - y
}

func TestImagePixels(t *testing.T) {
	img0, img, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}

	if got := img0.Bounds().Size(); got != img.Bounds().Size() {
		t.Errorf("img size: got %d; want %d", got, img.Bounds().Size())
	}

	for j := 0; j < img0.Bounds().Size().Y; j++ {
		for i := 0; i < img0.Bounds().Size().X; i++ {
			got := img0.At(i, j)
			want := color.RGBAModel.Convert(img.At(i, j))
			if got != want {
				t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
			}
		}
	}
}

func TestImageComposition(t *testing.T) {
	img2Color := color.NRGBA{0x24, 0x3f, 0x6a, 0x88}
	img3Color := color.NRGBA{0x85, 0xa3, 0x08, 0xd3}

	// TODO: Rename this to img0
	img1, _, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}

	w, h := img1.Bounds().Size().X, img1.Bounds().Size().Y

	img2, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}

	img3, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}

	if err := img2.Fill(img2Color); err != nil {
		t.Fatal(err)
		return
	}
	if err := img3.Fill(img3Color); err != nil {
		t.Fatal(err)
		return
	}
	img_12_3, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	if err := img2.DrawImage(img1, nil); err != nil {
		t.Fatal(err)
		return
	}
	if err := img3.DrawImage(img2, nil); err != nil {
		t.Fatal(err)
		return
	}
	if err := img_12_3.DrawImage(img3, nil); err != nil {
		t.Fatal(err)
		return
	}

	if err := img2.Fill(img2Color); err != nil {
		t.Fatal(err)
		return
	}
	if err := img3.Fill(img3Color); err != nil {
		t.Fatal(err)
		return
	}
	img_1_23, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	if err := img3.DrawImage(img2, nil); err != nil {
		t.Fatal(err)
		return
	}
	if err := img3.DrawImage(img1, nil); err != nil {
		t.Fatal(err)
		return
	}
	if err := img_1_23.DrawImage(img3, nil); err != nil {
		t.Fatal(err)
		return
	}

	for j := 0; j < h; j++ {
		for i := 0; i < w; i++ {
			c1 := img_12_3.At(i, j).(color.RGBA)
			c2 := img_1_23.At(i, j).(color.RGBA)
			if 1 < diff(c1.R, c2.R) || 1 < diff(c1.G, c2.G) || 1 < diff(c1.B, c2.B) || 1 < diff(c1.A, c2.A) {
				t.Errorf("img_12_3.At(%d, %d) = %#v; img_1_23.At(%[1]d, %[2]d) = %#[4]v", i, j, c1, c2)
			}
			if c1.A == 0 {
				t.Fatalf("img_12_3.At(%d, %d).A = 0; nothing is rendered?", i, j)
			}
			if c2.A == 0 {
				t.Fatalf("img_1_23.At(%d, %d).A = 0; nothing is rendered?", i, j)
			}
		}
	}
}

func TestImageSelf(t *testing.T) {
	img, _, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}
	if err := img.DrawImage(img, nil); err == nil {
		t.Fatalf("img.DrawImage(img, nil) doesn't return error; an error should be returned")
	}
}

func TestImageDotByDotInversion(t *testing.T) {
	img0, _, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}
	w, h := img0.Size()
	img1, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	op := &DrawImageOptions{}
	op.GeoM.Rotate(math.Pi)
	op.GeoM.Translate(float64(w), float64(h))
	if err := img1.DrawImage(img0, op); err != nil {
		t.Fatal(err)
		return
	}

	for j := 0; j < h; j++ {
		for i := 0; i < w; i++ {
			c0 := img0.At(i, j).(color.RGBA)
			c1 := img1.At(w-i-1, h-j-1).(color.RGBA)
			if c0 != c1 {
				t.Errorf("img0.At(%[1]d, %[2]d) should equal to img1.At(%[3]d, %[4]d) but not: %[5]v vs %[6]v", i, j, w-i-1, h-j-1, c0, c1)
			}
		}
	}
}

func TestReplacePixels(t *testing.T) {
	origImg, err := openImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}
	// Convert to RGBA
	img := image.NewRGBA(origImg.Bounds())
	draw.Draw(img, img.Bounds(), origImg, image.ZP, draw.Src)

	size := img.Bounds().Size()
	img0, err := NewImage(size.X, size.Y, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}

	if err := img0.ReplacePixels(img.Pix); err != nil {
		t.Fatal(err)
		return
	}
	for j := 0; j < img0.Bounds().Size().Y; j++ {
		for i := 0; i < img0.Bounds().Size().X; i++ {
			got := img0.At(i, j)
			want := img.At(i, j)
			if got != want {
				t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
			}
		}
	}

	p := make([]uint8, 4*size.X*size.Y)
	for i := range p {
		p[i] = 0x80
	}
	if err := img0.ReplacePixels(p); err != nil {
		t.Fatal(err)
		return
	}
	for j := 0; j < img0.Bounds().Size().Y; j++ {
		for i := 0; i < img0.Bounds().Size().X; i++ {
			got := img0.At(i, j)
			want := color.RGBA{p[4*i], p[4*i+1], p[4*i+2], p[4*i+3]}
			if got != want {
				t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
			}
		}
	}
}

func TestImageDispose(t *testing.T) {
	img, err := NewImage(16, 16, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	if err := img.Dispose(); err != nil {
		t.Errorf("img.Dipose() returns error: %v", err)
	}
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func TestImageCompositeModeLighter(t *testing.T) {
	img0, _, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}

	w, h := img0.Size()
	img1, err := NewImage(w, h, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	if err := img1.Fill(color.RGBA{0x01, 0x02, 0x03, 0x04}); err != nil {
		t.Fatal(err)
		return
	}
	op := &DrawImageOptions{}
	op.CompositeMode = CompositeModeLighter
	if err := img1.DrawImage(img0, op); err != nil {
		t.Fatal(err)
		return
	}
	for j := 0; j < img1.Bounds().Size().Y; j++ {
		for i := 0; i < img1.Bounds().Size().X; i++ {
			got := img1.At(i, j).(color.RGBA)
			want := img0.At(i, j).(color.RGBA)
			want.R = uint8(min(0xff, int(want.R)+1))
			want.G = uint8(min(0xff, int(want.G)+2))
			want.B = uint8(min(0xff, int(want.B)+3))
			want.A = uint8(min(0xff, int(want.A)+4))
			if got != want {
				t.Errorf("img1 At(%d, %d): got %#v; want %#v", i, j, got, want)
			}
		}
	}
}

func TestNewImageFromEbitenImage(t *testing.T) {
	img, _, err := openEbitenImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}
	if _, err := NewImageFromImage(img, FilterNearest); err != nil {
		t.Errorf("NewImageFromImage returns error: %v", err)
	}
}

func TestNewImageFromSubImage(t *testing.T) {
	img, err := openImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}
	w, h := img.Bounds().Dx(), img.Bounds().Dy()
	subImg := img.(*image.NRGBA).SubImage(image.Rect(1, 1, w-1, h-1))
	eimg, err := NewImageFromImage(subImg, FilterNearest)
	if err != nil {
		t.Fatal(err)
		return
	}
	sw, sh := subImg.Bounds().Dx(), subImg.Bounds().Dy()
	w2, h2 := eimg.Size()
	if w2 != sw {
		t.Errorf("eimg Width: got %#v; want %#v", w2, sw)
	}
	if h2 != sh {
		t.Errorf("eimg Width: got %#v; want %#v", h2, sh)
	}
	for j := 0; j < h2; j++ {
		for i := 0; i < w2; i++ {
			got := eimg.At(i, j)
			want := color.RGBAModel.Convert(img.At(i+1, j+1))
			if got != want {
				t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
			}
		}
	}
}