package test

import (
	domain "RenewCMS/internal/domain/image"
	"bytes"
	"errors"
	"image"
	"image/color"
	"image/gif"
	"testing"
)

func bandedTallImage() *image.NRGBA {
	canvas := image.NewNRGBA(image.Rect(0, 0, 20, 60))
	for y := 0; y < 60; y++ {
		fill := variantGreen
		if y < 15 {
			fill = variantRed
		}
		if y >= 45 {
			fill = variantBlue
		}
		for x := 0; x < 20; x++ {
			canvas.SetNRGBA(x, y, fill)
		}
	}
	return canvas
}

func globalPaletteGIF(t *testing.T, frames int) []byte {
	t.Helper()
	palette := color.Palette{color.White, color.Black, color.RGBA{R: 255, A: 255}, color.RGBA{B: 255, A: 255}}
	animation := &gif.GIF{Config: image.Config{ColorModel: palette, Width: 8, Height: 8}}
	for frame := 0; frame < frames; frame++ {
		paletted := image.NewPaletted(image.Rect(0, 0, 8, 8), palette)
		paletted.SetColorIndex(frame, frame, 1)
		animation.Image = append(animation.Image, paletted)
		animation.Delay = append(animation.Delay, 10)
	}
	var buffer bytes.Buffer
	if err := gif.EncodeAll(&buffer, animation); err != nil {
		t.Fatalf("gif encode failed: %v", err)
	}
	return buffer.Bytes()
}

func TestVariantGeometryPixelGaps(t *testing.T) {
	t.Run("Cover on a tall source keeps the middle band", func(t *testing.T) {
		rendered := renderVariant(t, encodePNG(t, bandedTallImage()), variantSettings(20, 20, domain.FitCover, domain.FormatPNG))

		decoded, _ := decodeImage(t, rendered.Content)
		if decoded.Bounds().Dx() != 20 || decoded.Bounds().Dy() != 20 {
			t.Fatalf("output = %v", decoded.Bounds())
		}
		for _, y := range []int{0, 10, 19} {
			if got := pixelAt(decoded, 10, y); got != variantGreen {
				t.Errorf("pixel 10,%d = %v, want green", y, got)
			}
		}
	})

	t.Run("Inside on a tall source scales the whole picture", func(t *testing.T) {
		rendered := renderVariant(t, encodePNG(t, bandedTallImage()), variantSettings(10, 30, domain.FitInside, domain.FormatPNG))

		decoded, _ := decodeImage(t, rendered.Content)
		if decoded.Bounds().Dx() != 10 || decoded.Bounds().Dy() != 30 {
			t.Fatalf("output = %v", decoded.Bounds())
		}
		want := map[int]color.NRGBA{1: variantRed, 15: variantGreen, 28: variantBlue}
		for y, expected := range want {
			assertNearColor(t, pixelAt(decoded, 5, y), expected)
		}
	})

	t.Run("Contain pads horizontally around a narrow source", func(t *testing.T) {
		rendered := renderVariant(t, encodePNG(t, variantSolidImage(20, 40, variantRed)), variantSettings(40, 40, domain.FitContain, domain.FormatPNG))

		decoded, _ := decodeImage(t, rendered.Content)
		for y := 0; y < 40; y += 13 {
			for _, x := range []int{0, 9, 30, 39} {
				if got := pixelAt(decoded, x, y); got.A != 0 {
					t.Fatalf("pixel %d,%d = %v, want transparent", x, y, got)
				}
			}
			for _, x := range []int{10, 19, 29} {
				if got := pixelAt(decoded, x, y); got != variantRed {
					t.Fatalf("pixel %d,%d = %v, want red", x, y, got)
				}
			}
		}
	})

	t.Run("Contain keeps a box that is larger in one direction only", func(t *testing.T) {
		for _, row := range []struct{ width, height, wantWidth, wantHeight int }{
			{200, 100, 200, 100},
			{100, 200, 100, 200},
		} {
			rendered := renderVariant(t, solidPNG(t, 100, 100), variantSettings(row.width, row.height, domain.FitContain, domain.FormatPNG))

			width, height := decodedSize(t, rendered.Content)
			if width != row.wantWidth || height != row.wantHeight {
				t.Errorf("output = %dx%d, want %dx%d", width, height, row.wantWidth, row.wantHeight)
			}
		}
	})
}

func TestAnimatedGIFDetectionWithGlobalPalette(t *testing.T) {
	animated, err := domain.IsAnimatedGIF(bytes.NewReader(globalPaletteGIF(t, 2)))
	if err != nil || !animated {
		t.Errorf("two frames: animated = %v, err = %v", animated, err)
	}

	animated, err = domain.IsAnimatedGIF(bytes.NewReader(globalPaletteGIF(t, 1)))
	if err != nil || animated {
		t.Errorf("one frame: animated = %v, err = %v", animated, err)
	}
}

func TestVariantRequestErrorMessages(t *testing.T) {
	unknown := domain.NewUnknownVariantError("thumb")
	if unknown.Error() != "unknown variant: thumb" || !errors.Is(unknown, domain.ErrUnknownVariant) {
		t.Errorf("unknown = %q", unknown.Error())
	}
	unsupported := domain.NewUnsupportedParameterError("w")
	if unsupported.Error() != "unsupported parameter: w" || !errors.Is(unsupported, domain.ErrUnsupportedParameter) {
		t.Errorf("unsupported = %q", unsupported.Error())
	}
}