// Copyright 2014 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 (
	. "github.com/hajimehoshi/ebiten"
	"image"
	"image/color"
	_ "image/png"
	"os"
	"testing"
)

func openImage(path string) (*Image, image.Image, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, nil, err
	}
	defer file.Close()

	img, _, err := image.Decode(file)
	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) {
	eimg, img, err := openImage("testdata/ebiten.png")
	if err != nil {
		t.Fatal(err)
		return
	}

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

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

	img1, _, err := openImage("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
	}

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

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

	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 := openImage("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")
	}
}

// TODO: Add more tests (e.g. DrawImage with color matrix)