package ui

import (
	"image/color"
	"testing"

	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/test"
	"fyne.io/fyne/v2/theme"
)

// isGray 判断颜色是否是无彩度的灰度色。
func isGray(c color.Color) bool {
	n := color.NRGBAModel.Convert(c).(color.NRGBA)
	return n.R == n.G && n.G == n.B
}

func TestThemeLabelRoundTrip(t *testing.T) {
	for _, mode := range []string{ThemeSystem, ThemeContrast, ThemeLight} {
		label := themeLabel(mode)
		if got := themeFromLabel(label); got != mode {
			t.Fatalf("主题 %q 的中文名 %q 反查应为 %q，实际 %q", mode, label, mode, got)
		}
	}
	if got := themeFromLabel("不存在的名字"); got != ThemeSystem {
		t.Fatalf("未知中文名应回落到 %q，实际 %q", ThemeSystem, got)
	}
	if len(themeOptions()) != 3 {
		t.Fatalf("主题下拉应有 3 个选项，实际 %v", themeOptions())
	}
}

func TestDarkPaletteIsPureBlackOnWhite(t *testing.T) {
	p := darkPalette()

	black := color.NRGBA{R: 0, G: 0, B: 0, A: 0xFF}
	white := color.NRGBA{R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF}
	if got := p[theme.ColorNameBackground]; got != black {
		t.Fatalf("黑白主题背景应为纯黑，实际 %v", got)
	}
	if got := p[theme.ColorNameForeground]; got != white {
		t.Fatalf("黑白主题文字应为纯白，实际 %v", got)
	}
	for name, c := range p {
		if !isGray(c) {
			t.Fatalf("黑白主题不应出现彩色：%s = %v", name, c)
		}
	}
}

func TestLightPaletteIsPureWhiteOnBlack(t *testing.T) {
	p := lightPalette()

	black := color.NRGBA{R: 0, G: 0, B: 0, A: 0xFF}
	white := color.NRGBA{R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF}
	if got := p[theme.ColorNameBackground]; got != white {
		t.Fatalf("浅色主题背景应为纯白，实际 %v", got)
	}
	if got := p[theme.ColorNameForeground]; got != black {
		t.Fatalf("浅色主题文字应为纯黑，实际 %v", got)
	}
	for name, c := range p {
		if !isGray(c) {
			t.Fatalf("浅色高对比主题不应出现彩色：%s = %v", name, c)
		}
	}
}

func TestMonoThemeFallsBackToDefault(t *testing.T) {
	th := newMonoTheme(darkPalette())

	black := color.NRGBA{R: 0, G: 0, B: 0, A: 0xFF}
	// 调色板里有的走调色板。
	if got := th.Color(theme.ColorNameBackground, theme.VariantDark); got != black {
		t.Fatalf("背景色应取自调色板，实际 %v", got)
	}
	// 调色板里没有的沿用默认主题。
	if got := th.Color(theme.ColorNameOverlayBackground, theme.VariantDark); got == nil {
		t.Fatal("未覆盖的颜色名应回落到默认主题")
	}
	if th.Font(fyne.TextStyle{}) == nil || th.Size(theme.SizeNamePadding) <= 0 {
		t.Fatal("字体与尺寸应沿用默认主题")
	}
}

func TestApplyThemeModeSwitchesTheme(t *testing.T) {
	app := test.NewApp()

	black := color.NRGBA{R: 0, G: 0, B: 0, A: 0xFF}
	white := color.NRGBA{R: 0xFF, G: 0xFF, B: 0xFF, A: 0xFF}

	applyThemeMode(ThemeContrast)
	mt, ok := app.Settings().Theme().(*monoTheme)
	if !ok {
		t.Fatalf("黑白模式应切到 monoTheme，实际 %T", app.Settings().Theme())
	}
	if got := mt.Color(theme.ColorNameBackground, app.Settings().ThemeVariant()); got != black {
		t.Fatalf("黑白模式背景应为纯黑，实际 %v", got)
	}

	applyThemeMode(ThemeLight)
	mt, ok = app.Settings().Theme().(*monoTheme)
	if !ok {
		t.Fatalf("浅色模式应切到 monoTheme，实际 %T", app.Settings().Theme())
	}
	if got := mt.Color(theme.ColorNameBackground, app.Settings().ThemeVariant()); got != white {
		t.Fatalf("浅色模式背景应为纯白，实际 %v", got)
	}

	applyThemeMode(ThemeSystem)
	if _, ok := app.Settings().Theme().(*monoTheme); ok {
		t.Fatal("跟随系统应还原默认主题")
	}
	if got := app.Settings().Theme().Color(theme.ColorNameBackground, app.Settings().ThemeVariant()); got == nil {
		t.Fatal("默认主题应能取到背景色")
	}
}