package ui

import (
	"image/color"

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

// 主题模式。
const (
	ThemeSystem   = "system"   // 跟随系统
	ThemeContrast = "contrast" // 黑白高对比
	ThemeLight    = "light"    // 浅色高对比
)

// themeLabel 返回主题模式的中文名。
func themeLabel(mode string) string {
	switch mode {
	case ThemeContrast:
		return "黑白高对比"
	case ThemeLight:
		return "浅色高对比"
	default:
		return "跟随系统"
	}
}

// themeOptions 返回设置页下拉里的可选项。
func themeOptions() []string {
	return []string{
		themeLabel(ThemeSystem),
		themeLabel(ThemeContrast),
		themeLabel(ThemeLight),
	}
}

// themeFromLabel 由中文名反查主题模式。
func themeFromLabel(label string) string {
	for _, mode := range []string{ThemeSystem, ThemeContrast, ThemeLight} {
		if themeLabel(mode) == label {
			return mode
		}
	}
	return ThemeSystem
}

// applyThemeMode 按主题模式切换界面主题。
func applyThemeMode(mode string) {
	app := fyne.CurrentApp()
	if app == nil {
		return
	}
	switch mode {
	case ThemeContrast:
		app.Settings().SetTheme(newMonoTheme(darkPalette()))
	case ThemeLight:
		app.Settings().SetTheme(newMonoTheme(lightPalette()))
	default:
		app.Settings().SetTheme(theme.DefaultTheme())
	}
}

// monoTheme 是一套纯灰度主题：所有颜色都去掉彩度，只靠明暗区分层级，
// 文字与背景的对比拉到最高。
type monoTheme struct {
	base   fyne.Theme
	colors map[fyne.ThemeColorName]color.Color
}

// newMonoTheme 用给定配色造一个主题，其余项沿用默认主题。
func newMonoTheme(palette map[fyne.ThemeColorName]color.Color) fyne.Theme {
	return &monoTheme{base: theme.DefaultTheme(), colors: palette}
}

func (t *monoTheme) Color(name fyne.ThemeColorName, variant fyne.ThemeVariant) color.Color {
	if c, ok := t.colors[name]; ok {
		return c
	}
	return t.base.Color(name, variant)
}

func (t *monoTheme) Font(style fyne.TextStyle) fyne.Resource { return t.base.Font(style) }

func (t *monoTheme) Icon(name fyne.ThemeIconName) fyne.Resource { return t.base.Icon(name) }

func (t *monoTheme) Size(name fyne.ThemeSizeName) float32 { return t.base.Size(name) }

// rgb 生成不透明灰度色。
func rgb(v uint8) color.NRGBA {
	return color.NRGBA{R: v, G: v, B: v, A: 0xFF}
}

// darkPalette 是黑白高对比（纯黑底）的配色。
func darkPalette() map[fyne.ThemeColorName]color.Color {
	return map[fyne.ThemeColorName]color.Color{
		theme.ColorNameBackground:                rgb(0x00),
		theme.ColorNameForeground:                rgb(0xFF),
		theme.ColorNameDisabled:                  rgb(0x8C),
		theme.ColorNameDisabledButton:            rgb(0x1A),
		theme.ColorNameButton:                    rgb(0x2E),
		theme.ColorNameHover:                     rgb(0x4A),
		theme.ColorNamePressed:                   rgb(0x1E),
		theme.ColorNameFocus:                     rgb(0xFF),
		theme.ColorNamePrimary:                   rgb(0xFF),
		theme.ColorNameForegroundOnPrimary:       rgb(0x00),
		theme.ColorNameSelection:                 rgb(0xFF),
		theme.ColorNameInputBackground:           rgb(0x0B),
		theme.ColorNameInputBorder:               rgb(0xE6),
		theme.ColorNamePlaceHolder:               rgb(0xA6),
		theme.ColorNameSeparator:                 rgb(0x5A),
		theme.ColorNameOverlayBackground:         rgb(0x11),
		theme.ColorNameMenuBackground:            rgb(0x16),
		theme.ColorNameHeaderBackground:          rgb(0x1C),
		theme.ColorNameInnerWindowBorder:         rgb(0x3A),
		theme.ColorNameInnerWindowBorderInactive: rgb(0x26),
		theme.ColorNameScrollBar:                 rgb(0x9A),
		theme.ColorNameScrollBarBackground:       rgb(0x1A),
		theme.ColorNameShadow:                    rgb(0x00),
		theme.ColorNameError:                     rgb(0xFF),
		theme.ColorNameForegroundOnError:         rgb(0x00),
		theme.ColorNameSuccess:                   rgb(0xFF),
		theme.ColorNameForegroundOnSuccess:       rgb(0x00),
		theme.ColorNameWarning:                   rgb(0xFF),
		theme.ColorNameForegroundOnWarning:       rgb(0x00),
		theme.ColorNameHyperlink:                 rgb(0xFF),
	}
}

// lightPalette 是浅色高对比（纯白底）的配色。
func lightPalette() map[fyne.ThemeColorName]color.Color {
	return map[fyne.ThemeColorName]color.Color{
		theme.ColorNameBackground:                rgb(0xFF),
		theme.ColorNameForeground:                rgb(0x00),
		theme.ColorNameDisabled:                  rgb(0x70),
		theme.ColorNameDisabledButton:            rgb(0xF0),
		theme.ColorNameButton:                    rgb(0xE0),
		theme.ColorNameHover:                     rgb(0xC8),
		theme.ColorNamePressed:                   rgb(0xD4),
		theme.ColorNameFocus:                     rgb(0x00),
		theme.ColorNamePrimary:                   rgb(0x00),
		theme.ColorNameForegroundOnPrimary:       rgb(0xFF),
		theme.ColorNameSelection:                 rgb(0x00),
		theme.ColorNameInputBackground:           rgb(0xFF),
		theme.ColorNameInputBorder:               rgb(0x00),
		theme.ColorNamePlaceHolder:               rgb(0x70),
		theme.ColorNameSeparator:                 rgb(0x9A),
		theme.ColorNameOverlayBackground:         rgb(0xF4),
		theme.ColorNameMenuBackground:            rgb(0xFA),
		theme.ColorNameHeaderBackground:          rgb(0xEF),
		theme.ColorNameInnerWindowBorder:         rgb(0xC0),
		theme.ColorNameInnerWindowBorderInactive: rgb(0xD8),
		theme.ColorNameScrollBar:                 rgb(0x55),
		theme.ColorNameScrollBarBackground:       rgb(0xED),
		theme.ColorNameShadow:                    rgb(0x00),
		theme.ColorNameError:                     rgb(0x00),
		theme.ColorNameForegroundOnError:         rgb(0xFF),
		theme.ColorNameSuccess:                   rgb(0x00),
		theme.ColorNameForegroundOnSuccess:       rgb(0xFF),
		theme.ColorNameWarning:                   rgb(0x00),
		theme.ColorNameForegroundOnWarning:       rgb(0xFF),
		theme.ColorNameHyperlink:                 rgb(0x00),
	}
}