package photos

import (
	"bytes"
	"image"
	"image/png"
	"math"
	"testing"
)

func TestParseEditParamsClampsValues(t *testing.T) {
	raw := []byte(`{"light":{"exposure":99,"contrast":-500,"highlights":10,"curve":{"rgb":[{"x":2,"y":-1},{"x":0.5,"y":0.5}]}}}`)
	params, err := ParseEditParams(raw)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if params.Light.Exposure != MaxExposureStops {
		t.Fatalf("exposure = %v, want %v", params.Light.Exposure, MaxExposureStops)
	}
	if params.Light.Contrast != -MaxPercent {
		t.Fatalf("contrast = %v, want %v", params.Light.Contrast, -MaxPercent)
	}
	if len(params.Light.Curve.RGB) != 2 {
		t.Fatalf("curve points = %d, want 2", len(params.Light.Curve.RGB))
	}
	// Точки сортируются по X, а значения зажимаются в диапазон 0..1.
	first := params.Light.Curve.RGB[0]
	if first.X != 0.5 || first.Y != 0.5 {
		t.Fatalf("first curve point = %+v, want {0.5 0.5}", first)
	}
	second := params.Light.Curve.RGB[1]
	if second.X != 1 || second.Y != 0 {
		t.Fatalf("second curve point = %+v, want {1 0}", second)
	}
}

func TestEditRolesCoverTheEditedVersion(t *testing.T) {
	roles := EditRoles()
	if len(roles) != 4 {
		t.Fatalf("edit roles = %v, want four", roles)
	}
	for _, role := range roles {
		if !IsEditRole(role) {
			t.Fatalf("role %q must be an edit role", role)
		}
	}
	for _, role := range []string{RoleOriginal, RoleThumb, RoleMedium, RolePreview, RolePlayback} {
		if IsEditRole(role) {
			t.Fatalf("role %q must not be an edit role", role)
		}
	}
}

func TestEditParamsIsEmpty(t *testing.T) {
	var zero EditParams
	if !zero.IsEmpty() {
		t.Fatal("zero params must be empty")
	}
	zero.Light.Exposure = 0.1
	if zero.IsEmpty() {
		t.Fatal("params with exposure must not be empty")
	}
	curved := EditParams{}
	curved.Light.Curve.RGB = []CurvePoint{{X: 0, Y: 0}, {X: 1, Y: 0.5}}
	if curved.IsEmpty() {
		t.Fatal("params with a bent curve must not be empty")
	}
	linear := EditParams{}
	linear.Light.Curve.RGB = []CurvePoint{{X: 0, Y: 0}, {X: 1, Y: 1}}
	if !linear.IsEmpty() {
		t.Fatal("a linear curve must count as empty")
	}
}

func TestCurveLUTIdentity(t *testing.T) {
	lut := curveLUT(nil)
	for i := 0; i < 256; i++ {
		if int(lut[i]) != i {
			t.Fatalf("lut[%d] = %d, want %d", i, lut[i], i)
		}
	}
}

func TestCurveLUTSteepens(t *testing.T) {
	lut := curveLUT([]CurvePoint{{X: 0, Y: 0}, {X: 0.5, Y: 0.25}, {X: 1, Y: 1}})
	if lut[0] != 0 || lut[255] != 255 {
		t.Fatalf("curve ends = %d..%d, want 0..255", lut[0], lut[255])
	}
	if lut[128] >= 128 {
		t.Fatalf("lut[128] = %d, want a darker midtone", lut[128])
	}
}

func TestApplyLightBrightensAndKeepsSource(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 2, 2))
	for i := range src.Pix {
		src.Pix[i] = 100
	}
	src.Pix[3] = 255
	before := make([]byte, len(src.Pix))
	copy(before, src.Pix)

	edited := applyLight(src, LightParams{Exposure: 1})
	if edited.Pix[0] <= before[0] {
		t.Fatalf("exposure did not brighten: %d <= %d", edited.Pix[0], before[0])
	}
	for i := range src.Pix {
		if src.Pix[i] != before[i] {
			t.Fatalf("source pixel %d changed: %d != %d", i, src.Pix[i], before[i])
		}
	}
}

func TestApplyLightContrast(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	for i := range src.Pix {
		src.Pix[i] = 200
	}
	src.Pix[3] = 255
	edited := applyLight(src, LightParams{Contrast: 50})
	if edited.Pix[0] <= 200 {
		t.Fatalf("contrast did not push the bright tone up: %d", edited.Pix[0])
	}
	// Контраст работает вокруг средней точки: тёмные тона уходят вниз.
	dark := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	for i := range dark.Pix {
		dark.Pix[i] = 60
	}
	dark.Pix[3] = 255
	editedDark := applyLight(dark, LightParams{Contrast: 50})
	if editedDark.Pix[0] >= 60 {
		t.Fatalf("contrast did not push the dark tone down: %d", editedDark.Pix[0])
	}
}

func TestBuildEditedVariants(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 400, 300))
	for y := 0; y < 300; y++ {
		for x := 0; x < 400; x++ {
			i := y*src.Stride + x*4
			src.Pix[i] = uint8(x % 256)
			src.Pix[i+1] = uint8(y % 256)
			src.Pix[i+2] = 128
			src.Pix[i+3] = 255
		}
	}
	edited, err := decodeAndAdjust(mustEncodePNG(t, src), EditParams{Light: LightParams{Exposure: 0.5}})
	if err != nil {
		t.Fatalf("decode and adjust: %v", err)
	}
	thumb, medium, preview, err := encodeEditedVariants(edited)
	if err != nil {
		t.Fatalf("encode variants: %v", err)
	}
	full, err := encodeEdited(edited)
	if err != nil {
		t.Fatalf("encode full: %v", err)
	}
	if len(thumb) == 0 || len(medium) == 0 || len(preview) == 0 || len(full) == 0 {
		t.Fatalf("empty variants: %d %d %d %d", len(thumb), len(medium), len(preview), len(full))
	}
}

func TestAdjustChannelClamps(t *testing.T) {
	lut := curveLUT(nil)
	if v := adjustChannel(255, LightParams{Exposure: 5}, &lut, &lut); v != 255 {
		t.Fatalf("value = %v, want 255", v)
	}
	if v := adjustChannel(0, LightParams{Exposure: -5}, &lut, &lut); v != 0 {
		t.Fatalf("value = %v, want 0", v)
	}
	if v := adjustChannel(128, LightParams{Contrast: 0}, &lut, &lut); math.Abs(v-128) > 0.001 {
		t.Fatalf("value = %v, want 128", v)
	}
}

func mustEncodePNG(t *testing.T, img image.Image) []byte {
	t.Helper()
	var buf bytes.Buffer
	if err := png.Encode(&buf, img); err != nil {
		t.Fatalf("encode png: %v", err)
	}
	return buf.Bytes()
}

func TestParseEditParamsClampsColor(t *testing.T) {
	raw := []byte(`{"color":{"temperature":200,"tint":-300,"vibrance":50,"saturation":-500,"mixer":{"red":{"hue":150,"saturation":-200,"luminance":10}},"grading":{"shadows":{"hue":400,"saturation":150},"balance":-200},"correction":{"red":120}}}`)
	params, err := ParseEditParams(raw)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	c := params.Color
	if c.Temperature != MaxPercent || c.Tint != -MaxPercent {
		t.Fatalf("wb = %v/%v, want clamped", c.Temperature, c.Tint)
	}
	if c.Saturation != -MaxPercent {
		t.Fatalf("saturation = %v, want %v", c.Saturation, -MaxPercent)
	}
	if c.Mixer.Red.Hue != MaxPercent || c.Mixer.Red.Saturation != -MaxPercent {
		t.Fatalf("mixer red = %+v, want clamped", c.Mixer.Red)
	}
	if c.Grading.Shadows.Hue != 360 || c.Grading.Shadows.Saturation != MaxPercent {
		t.Fatalf("grading shadows = %+v, want clamped", c.Grading.Shadows)
	}
	if c.Grading.Balance != -MaxPercent || c.Correction.Red != MaxPercent {
		t.Fatalf("grading/correction not clamped: %+v %+v", c.Grading, c.Correction)
	}
}

func TestColorParamsIsEmpty(t *testing.T) {
	var zero ColorParams
	if !zero.IsEmpty() {
		t.Fatal("zero color params must be empty")
	}
	vibrance := ColorParams{Vibrance: 1}
	if vibrance.IsEmpty() {
		t.Fatal("vibrance must not be empty")
	}
	mixer := ColorParams{}
	mixer.Mixer.Blue.Luminance = -10
	if mixer.IsEmpty() {
		t.Fatal("mixer band must not be empty")
	}
	// Оттенок колеса без силы не влияет на картинку.
	hueOnly := ColorParams{}
	hueOnly.Grading.Shadows.Hue = 120
	if !hueOnly.IsEmpty() {
		t.Fatal("grading hue without strength must count as empty")
	}
	grade := ColorParams{}
	grade.Grading.Highlights.Saturation = 10
	if grade.IsEmpty() {
		t.Fatal("grading strength must not be empty")
	}
}

func TestApplyColorWhiteBalance(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 100, 100, 100, 255
	out := applyColor(src, ColorParams{Temperature: 100})
	if !(out.Pix[0] > out.Pix[1] && out.Pix[1] > out.Pix[2]) {
		t.Fatalf("warm white balance = %d/%d/%d, want r > g > b", out.Pix[0], out.Pix[1], out.Pix[2])
	}
}

func TestApplyColorSaturationMinus100IsGray(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 200, 50, 50, 255
	out := applyColor(src, ColorParams{Saturation: -100})
	if out.Pix[0] != out.Pix[1] || out.Pix[1] != out.Pix[2] {
		t.Fatalf("desaturated pixel = %d/%d/%d, want gray", out.Pix[0], out.Pix[1], out.Pix[2])
	}
}

func TestApplyColorSaturationPlus100(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 150, 120, 120, 255
	before := src.Pix[0] - src.Pix[1]
	out := applyColor(src, ColorParams{Saturation: 100})
	if out.Pix[0]-out.Pix[1] <= before {
		t.Fatalf("saturation did not spread channels: %d/%d/%d", out.Pix[0], out.Pix[1], out.Pix[2])
	}
}

func TestApplyColorGradingTintsShadows(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 40, 40, 40, 255
	p := ColorParams{}
	p.Grading.Blending = 50
	p.Grading.Shadows = ColorWheel{Hue: 240, Saturation: 100}
	out := applyColor(src, p)
	if out.Pix[2] <= out.Pix[0] {
		t.Fatalf("blue shadow grading = %d/%d/%d, want b > r", out.Pix[0], out.Pix[1], out.Pix[2])
	}
}

func TestApplyColorGradingLuminance(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 40, 40, 40, 255
	p := ColorParams{}
	p.Grading.Shadows = ColorWheel{Luminance: 100}
	out := applyColor(src, p)
	if out.Pix[0] <= 40 {
		t.Fatalf("shadow luminance did not brighten: %d", out.Pix[0])
	}
}

func TestApplyColorUniformRows(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 64, 64))
	for i := 0; i < len(src.Pix); i += 4 {
		src.Pix[i], src.Pix[i+1], src.Pix[i+2], src.Pix[i+3] = 40, 40, 40, 255
	}
	p := ColorParams{}
	p.Grading.Blending = 50
	p.Grading.Shadows = ColorWheel{Hue: 240, Saturation: 100}
	out := applyColor(src, p)
	wantR, wantG, wantB := out.Pix[0], out.Pix[1], out.Pix[2]
	for y := 0; y < 64; y++ {
		for x := 0; x < 64; x++ {
			i := y*out.Stride + x*4
			if out.Pix[i] != wantR || out.Pix[i+1] != wantG || out.Pix[i+2] != wantB {
				t.Fatalf("pixel (%d,%d) = %d/%d/%d, want %d/%d/%d", x, y, out.Pix[i], out.Pix[i+1], out.Pix[i+2], wantR, wantG, wantB)
			}
		}
	}
}

func TestApplyColorParallelMatchesSingle(t *testing.T) {
	makeImage := func() *image.NRGBA {
		img := image.NewNRGBA(image.Rect(0, 0, 32, 64))
		for y := 0; y < 64; y++ {
			for x := 0; x < 32; x++ {
				i := y*img.Stride + x*4
				img.Pix[i] = uint8(20 + y*3)
				img.Pix[i+1] = uint8(20 + y*2)
				img.Pix[i+2] = uint8(30 + y)
				img.Pix[i+3] = 255
			}
		}
		return img
	}
	p := ColorParams{}
	p.Grading.Blending = 50
	p.Grading.Shadows = ColorWheel{Hue: 240, Saturation: 100}

	parallel := applyColor(makeImage(), p)
	single := makeImage()
	applyColorRows(single, 0, single.Rect.Dy(), newColorAdjuster(p))

	for i := range parallel.Pix {
		if parallel.Pix[i] != single.Pix[i] {
			t.Fatalf("parallel differs at byte %d: %d != %d", i, parallel.Pix[i], single.Pix[i])
		}
	}
}

func TestApplyColorKeepsTransparentPixels(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 1, 1))
	src.Pix[0], src.Pix[1], src.Pix[2], src.Pix[3] = 10, 20, 30, 0
	out := applyColor(src, ColorParams{Saturation: 100, Temperature: 100})
	if out.Pix[0] != 10 || out.Pix[1] != 20 || out.Pix[2] != 30 || out.Pix[3] != 0 {
		t.Fatalf("transparent pixel changed: %v", out.Pix)
	}
}

func TestParseEditParamsWithoutColorIsBackwardCompatible(t *testing.T) {
	params, err := ParseEditParams([]byte(`{"light":{"exposure":0.5}}`))
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	if !params.Color.IsEmpty() {
		t.Fatalf("missing color must be empty: %+v", params.Color)
	}
	if params.IsEmpty() {
		t.Fatal("light edits must not be empty")
	}
}

func TestApplyColorEmptyIsIdentity(t *testing.T) {
	src := image.NewNRGBA(image.Rect(0, 0, 3, 1))
	colors := [][3]uint8{{0, 0, 0}, {200, 50, 25}, {33, 210, 128}}
	for i, c := range colors {
		src.Pix[i*4] = c[0]
		src.Pix[i*4+1] = c[1]
		src.Pix[i*4+2] = c[2]
		src.Pix[i*4+3] = 255
	}
	before := make([]byte, len(src.Pix))
	copy(before, src.Pix)
	applyColor(src, ColorParams{})
	for i := range before {
		if before[i] != src.Pix[i] {
			t.Fatalf("empty color changed pixel %d: %d != %d", i, src.Pix[i], before[i])
		}
	}
}