package application

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

func TestApplyAnnotationsDrawsIntoPNG(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 40, 40))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)

	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}

	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{
		{
			Tool:  "rect",
			Color: "#ef4444",
			Points: []Point{
				{X: 5, Y: 5},
				{X: 30, Y: 30},
			},
		},
	}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}

	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	if got := color.RGBAModel.Convert(img.At(5, 5)).(color.RGBA); got.R != 0xef || got.G != 0x44 || got.B != 0x44 {
		t.Fatalf("expected annotated pixel at rectangle edge, got %#v", got)
	}
}

func TestApplyAnnotationsNoAnnotationsReturnsOriginalBytes(t *testing.T) {
	original := []byte("not decoded when no annotations")
	out, err := ApplyAnnotations(original, nil, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}
	if !bytes.Equal(out, original) {
		t.Fatalf("expected original bytes")
	}
}

func TestApplyAnnotationsDrawsTextIntoPNG(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 120, 80))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)

	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}

	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{
		{
			Tool:  "text",
			Color: "#ef4444",
			Points: []Point{
				{X: 10, Y: 10},
			},
			Text: "T",
		},
	}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}

	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	found := false
	for y := 8; y < 40 && !found; y++ {
		for x := 8; x < 40; x++ {
			got := color.RGBAModel.Convert(img.At(x, y)).(color.RGBA)
			if got.R > 180 && got.G < 180 && got.B < 180 {
				found = true
				break
			}
		}
	}
	if !found {
		t.Fatalf("expected red text pixels near annotation point")
	}
}

func TestApplyAnnotationsWithScaleDrawsTextAtDevicePosition(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 220, 120))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)

	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}

	out, err := ApplyAnnotationsWithScale(buf.Bytes(), []Annotation{
		{
			Tool:     "text",
			Color:    "#ef4444",
			Points:   []Point{{X: 50, Y: 20}},
			Text:     "T",
			FontSize: 20,
		},
	}, 2, 2)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}

	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	minX := 999
	found := false
	for y := 0; y < img.Bounds().Dy(); y++ {
		for x := 0; x < img.Bounds().Dx(); x++ {
			got := color.RGBAModel.Convert(img.At(x, y)).(color.RGBA)
			if got.R > 180 && got.G < 180 && got.B < 180 {
				found = true
				if x < minX {
					minX = x
				}
			}
		}
	}
	if !found {
		t.Fatalf("expected red text pixels")
	}
	if minX < 90 {
		t.Fatalf("expected text to be drawn near scaled x=100, min red x=%d", minX)
	}
}

func TestApplyAnnotationsUsesStrokeWidth(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 80, 80))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)

	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}

	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{
		{
			Tool:        "rect",
			Color:       "#ef4444",
			Points:      []Point{{X: 20, Y: 20}, {X: 60, Y: 60}},
			StrokeWidth: 8,
		},
	}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}

	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	got := color.RGBAModel.Convert(img.At(20, 24)).(color.RGBA)
	if got.R < 180 || got.G > 180 || got.B > 180 {
		t.Fatalf("expected thick rectangle stroke to cover y=24, got %#v", got)
	}
}

func TestApplyAnnotationsPixelatesMosaicRectangle(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 40, 30))
	for y := 0; y < 30; y++ {
		for x := 0; x < 40; x++ {
			src.SetRGBA(x, y, color.RGBA{R: uint8(x * 6), G: uint8(y * 8), B: uint8((x + y) * 3), A: 255})
		}
	}
	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}
	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{{
		Tool: "mosaic-rect", Points: []Point{{X: 10, Y: 5}, {X: 30, Y: 25}},
	}}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}
	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	if img.At(12, 7) != img.At(18, 13) {
		t.Fatalf("expected pixels in one mosaic block to share a color")
	}
	if img.At(5, 5) != src.At(5, 5) {
		t.Fatalf("expected pixels outside mosaic rectangle to remain unchanged")
	}
}

func TestApplyAnnotationsPixelatesOnlyMosaicBrushStroke(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 50, 30))
	for y := 0; y < 30; y++ {
		for x := 0; x < 50; x++ {
			src.SetRGBA(x, y, color.RGBA{R: uint8(x * 5), G: uint8(y * 8), A: 255})
		}
	}
	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}
	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{{
		Tool: "mosaic-brush", StrokeWidth: 12, Points: []Point{{X: 5, Y: 15}, {X: 45, Y: 15}},
	}}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}
	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	if img.At(12, 15) == src.At(12, 15) {
		t.Fatalf("expected brush path to be pixelated")
	}
	if img.At(12, 2) != src.At(12, 2) {
		t.Fatalf("expected pixels outside brush path to remain unchanged")
	}
}

func TestApplyAnnotationsDrawsStraightLine(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 60, 40))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)
	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}
	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{{
		Tool: "line", Color: "#ef4444", StrokeWidth: 4,
		Points: []Point{{X: 5, Y: 20}, {X: 50, Y: 20}},
	}}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}
	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	got := color.RGBAModel.Convert(img.At(30, 20)).(color.RGBA)
	if got.R < 180 || got.G > 180 || got.B > 180 {
		t.Fatalf("expected red line at center, got %#v", got)
	}
}

func TestApplyAnnotationsDrawsArrowHead(t *testing.T) {
	src := image.NewRGBA(image.Rect(0, 0, 80, 60))
	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)
	var buf bytes.Buffer
	if err := png.Encode(&buf, src); err != nil {
		t.Fatalf("encode source: %v", err)
	}
	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{{
		Tool: "arrow", Color: "#3b82f6", StrokeWidth: 3,
		Points: []Point{{X: 10, Y: 30}, {X: 60, Y: 30}},
	}}, 1)
	if err != nil {
		t.Fatalf("apply annotations: %v", err)
	}
	img, err := png.Decode(bytes.NewReader(out))
	if err != nil {
		t.Fatalf("decode output: %v", err)
	}
	shaft := color.RGBAModel.Convert(img.At(35, 30)).(color.RGBA)
	head := color.RGBAModel.Convert(img.At(52, 25)).(color.RGBA)
	if shaft.B < 180 || shaft.R > 140 || head.B < 180 || head.R > 140 {
		t.Fatalf("expected blue arrow shaft and head, got shaft=%#v head=%#v", shaft, head)
	}
}