package renderer

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

	"github.com/kevin/go-jdenticon/internal/engine"
)

func TestNewPNGRenderer(t *testing.T) {
	renderer := NewPNGRenderer(100)

	if renderer.iconSize != 100 {
		t.Errorf("NewPNGRenderer(100).iconSize = %v, want 100", renderer.iconSize)
	}
	if renderer.img == nil {
		t.Error("img should be initialized")
	}
	if renderer.img.Bounds().Max.X != 100 || renderer.img.Bounds().Max.Y != 100 {
		t.Errorf("image bounds = %v, want 100x100", renderer.img.Bounds())
	}
}

func TestPNGRenderer_SetBackground(t *testing.T) {
	renderer := NewPNGRenderer(50)

	renderer.SetBackground("#ff0000", 1.0)

	if !renderer.hasBackground {
		t.Error("hasBackground should be true")
	}
	if renderer.backgroundOp != 1.0 {
		t.Errorf("backgroundOp = %v, want 1.0", renderer.backgroundOp)
	}

	// Check that background was actually set
	expectedColor := color.RGBA{R: 255, G: 0, B: 0, A: 255}
	if renderer.background != expectedColor {
		t.Errorf("background color = %v, want %v", renderer.background, expectedColor)
	}

	// Check that image was filled with background
	actualColor := renderer.img.RGBAAt(25, 25)
	if actualColor != expectedColor {
		t.Errorf("image pixel color = %v, want %v", actualColor, expectedColor)
	}
}

func TestPNGRenderer_SetBackgroundWithOpacity(t *testing.T) {
	renderer := NewPNGRenderer(50)

	renderer.SetBackground("#00ff00", 0.5)

	expectedColor := color.RGBA{R: 0, G: 255, B: 0, A: 128}
	if renderer.background != expectedColor {
		t.Errorf("background color = %v, want %v", renderer.background, expectedColor)
	}
}

func TestPNGRenderer_BeginEndShape(t *testing.T) {
	renderer := NewPNGRenderer(100)

	renderer.BeginShape("#0000ff")
	expectedColor := color.RGBA{R: 0, G: 0, B: 255, A: 255}
	if renderer.currentColor != expectedColor {
		t.Errorf("currentColor = %v, want %v", renderer.currentColor, expectedColor)
	}

	renderer.EndShape()
	// EndShape is a no-op for PNG, just verify it doesn't panic
}

func TestPNGRenderer_AddPolygon(t *testing.T) {
	renderer := NewPNGRenderer(100)
	renderer.BeginShape("#ff0000")

	// Create a simple triangle
	points := []engine.Point{
		{X: 10, Y: 10},
		{X: 30, Y: 10},
		{X: 20, Y: 30},
	}

	renderer.AddPolygon(points)

	// Check that some pixels in the triangle are red
	redColor := color.RGBA{R: 255, G: 0, B: 0, A: 255}
	centerPixel := renderer.img.RGBAAt(20, 15) // Should be inside triangle
	if centerPixel != redColor {
		t.Errorf("triangle center pixel = %v, want %v", centerPixel, redColor)
	}

	// Check that pixels outside triangle are not red (should be transparent)
	outsidePixel := renderer.img.RGBAAt(5, 5)
	if outsidePixel == redColor {
		t.Error("pixel outside triangle should not be red")
	}
}

func TestPNGRenderer_AddPolygonEmpty(t *testing.T) {
	renderer := NewPNGRenderer(100)
	renderer.BeginShape("#ff0000")

	// Empty polygon should not panic
	renderer.AddPolygon([]engine.Point{})

	// Polygon with < 3 points should not panic
	renderer.AddPolygon([]engine.Point{{X: 10, Y: 10}})
	renderer.AddPolygon([]engine.Point{{X: 10, Y: 10}, {X: 20, Y: 20}})
}

func TestPNGRenderer_AddCircle(t *testing.T) {
	renderer := NewPNGRenderer(100)
	renderer.BeginShape("#00ff00")

	// Circle with center at (50, 50) and radius 20 means topLeft at (30, 30) and size 40
	topLeft := engine.Point{X: 30, Y: 30}
	size := 40.0

	renderer.AddCircle(topLeft, size, false)

	// Check that center pixel is green
	greenColor := color.RGBA{R: 0, G: 255, B: 0, A: 255}
	centerPixel := renderer.img.RGBAAt(50, 50)
	if centerPixel != greenColor {
		t.Errorf("circle center pixel = %v, want %v", centerPixel, greenColor)
	}

	// Check that a pixel clearly outside the circle is not green
	outsidePixel := renderer.img.RGBAAt(10, 10)
	if outsidePixel == greenColor {
		t.Error("pixel outside circle should not be green")
	}
}

func TestPNGRenderer_AddCircleInvert(t *testing.T) {
	renderer := NewPNGRenderer(100)

	// First fill with background
	renderer.SetBackground("#ffffff", 1.0)
	renderer.BeginShape("#ff0000")

	// Add inverted circle (should punch a hole)
	// Circle with center at (50, 50) and radius 20 means topLeft at (30, 30) and size 40
	topLeft := engine.Point{X: 30, Y: 30}
	size := 40.0

	renderer.AddCircle(topLeft, size, true)

	// Check that center pixel is transparent (inverted)
	centerPixel := renderer.img.RGBAAt(50, 50)
	if centerPixel.A != 0 {
		t.Errorf("inverted circle center should be transparent, got %v", centerPixel)
	}
}

func TestPNGRenderer_ToPNG(t *testing.T) {
	renderer := NewPNGRenderer(50)
	renderer.SetBackground("#ffffff", 1.0)

	renderer.BeginShape("#ff0000")
	points := []engine.Point{
		{X: 10, Y: 10},
		{X: 40, Y: 10},
		{X: 40, Y: 40},
		{X: 10, Y: 40},
	}
	renderer.AddPolygon(points)

	pngData := renderer.ToPNG()

	if len(pngData) == 0 {
		t.Error("ToPNG() should return non-empty data")
	}

	// Verify it's valid PNG data by decoding it
	reader := bytes.NewReader(pngData)
	decodedImg, err := png.Decode(reader)
	if err != nil {
		t.Errorf("ToPNG() returned invalid PNG data: %v", err)
	}

	// Check dimensions
	bounds := decodedImg.Bounds()
	if bounds.Max.X != 50 || bounds.Max.Y != 50 {
		t.Errorf("decoded image bounds = %v, want 50x50", bounds)
	}
}

func TestPNGRenderer_ToPNGEmpty(t *testing.T) {
	renderer := NewPNGRenderer(10)

	pngData := renderer.ToPNG()

	if len(pngData) == 0 {
		t.Error("ToPNG() should return data even for empty image")
	}

	// Should be valid PNG
	reader := bytes.NewReader(pngData)
	_, err := png.Decode(reader)
	if err != nil {
		t.Errorf("ToPNG() returned invalid PNG data: %v", err)
	}
}

func TestParseColor(t *testing.T) {
	tests := []struct {
		input    string
		opacity  float64
		expected color.RGBA
	}{
		{"#ff0000", 1.0, color.RGBA{R: 255, G: 0, B: 0, A: 255}},
		{"ff0000", 1.0, color.RGBA{R: 255, G: 0, B: 0, A: 255}},
		{"#00ff00", 0.5, color.RGBA{R: 0, G: 255, B: 0, A: 128}},
		{"#0000ff", 0.0, color.RGBA{R: 0, G: 0, B: 255, A: 0}},
		{"#f00", 1.0, color.RGBA{R: 255, G: 0, B: 0, A: 255}},
		{"#0f0", 1.0, color.RGBA{R: 0, G: 255, B: 0, A: 255}},
		{"#00f", 1.0, color.RGBA{R: 0, G: 0, B: 255, A: 255}},
		{"#ff0000ff", 1.0, color.RGBA{R: 255, G: 0, B: 0, A: 255}},
		{"#ff000080", 1.0, color.RGBA{R: 255, G: 0, B: 0, A: 128}},
		{"invalid", 1.0, color.RGBA{R: 0, G: 0, B: 0, A: 255}},
		{"", 1.0, color.RGBA{R: 0, G: 0, B: 0, A: 255}},
	}

	for _, test := range tests {
		result := parseColor(test.input, test.opacity)
		if result != test.expected {
			t.Errorf("parseColor(%q, %v) = %v, want %v",
				test.input, test.opacity, result, test.expected)
		}
	}
}

func TestPNGRenderer_ConcurrentAccess(t *testing.T) {
	renderer := NewPNGRenderer(100)

	// Test concurrent access to ensure thread safety
	done := make(chan bool, 10)

	for i := 0; i < 10; i++ {
		go func(id int) {
			renderer.BeginShape("#ff0000")
			points := []engine.Point{
				{X: float64(id * 5), Y: float64(id * 5)},
				{X: float64(id*5 + 10), Y: float64(id * 5)},
				{X: float64(id*5 + 10), Y: float64(id*5 + 10)},
				{X: float64(id * 5), Y: float64(id*5 + 10)},
			}
			renderer.AddPolygon(points)
			renderer.EndShape()
			done <- true
		}(i)
	}

	// Wait for all goroutines to complete
	for i := 0; i < 10; i++ {
		<-done
	}

	// Should be able to generate PNG without issues
	pngData := renderer.ToPNG()
	if len(pngData) == 0 {
		t.Error("concurrent access test failed - no PNG data generated")
	}
}

func BenchmarkPNGRenderer_ToPNG(b *testing.B) {
	renderer := NewPNGRenderer(200)
	renderer.SetBackground("#ffffff", 1.0)

	// Add some shapes for a realistic benchmark
	renderer.BeginShape("#ff0000")
	renderer.AddPolygon([]engine.Point{
		{X: 20, Y: 20}, {X: 80, Y: 20}, {X: 80, Y: 80}, {X: 20, Y: 80},
	})

	renderer.BeginShape("#00ff00")
	renderer.AddCircle(engine.Point{X: 100, Y: 100}, 30, false)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		pngData := renderer.ToPNG()
		if len(pngData) == 0 {
			b.Fatal("ToPNG returned empty data")
		}
	}
}