agentu/internal/tui/theme.go

package tui

import (
	"fmt"
	"strings"

	"github.com/charmbracelet/bubbles/textarea"
	"github.com/charmbracelet/lipgloss"
)

type ThemeMode string

const (
	ThemeLight ThemeMode = "light"
	ThemeDark  ThemeMode = "dark"
)

const (
	iconReady   = "✓"
	iconWorking = "◆"
	iconTool    = "▣"
	iconError   = "✕"
	iconCommand = "⌘"
	iconSession = "◌"
	iconContext = "◔"
	iconModel   = "◉"
)

func ParseThemeMode(value string) (ThemeMode, error) {
	switch ThemeMode(strings.ToLower(strings.TrimSpace(value))) {
	case "", ThemeLight:
		return ThemeLight, nil
	case ThemeDark:
		return ThemeDark, nil
	default:
		return "", fmt.Errorf("unsupported theme %q; expected light or dark", value)
	}
}

type theme struct {
	Mode ThemeMode

	Background string
	Surface    string
	SurfaceAlt string
	InputBg    string
	Border     string
	Text       string
	Muted      string

	Title     string
	User      string
	Assistant string
	Tool      string
	Error     string
	System    string
}

type styles struct {
	App               lipgloss.Style
	Muted             lipgloss.Style
	Activity          lipgloss.Style
	Header            lipgloss.Style
	Footer            lipgloss.Style
	Viewport          lipgloss.Style
	InputBox          lipgloss.Style
	CommandHint       lipgloss.Style
	InputModeReadonly lipgloss.Style
	InputModeYolo     lipgloss.Style
	InputModeCommand  lipgloss.Style
	StatusReady       lipgloss.Style
	StatusWarn        lipgloss.Style
	StatusError       lipgloss.Style
	StatusInfo        lipgloss.Style
	Pill              lipgloss.Style
	PillAccent        lipgloss.Style
	Palette           lipgloss.Style
	PaletteMatch      lipgloss.Style
	ToolName          lipgloss.Style
	ToolKey           lipgloss.Style
	ToolValue         lipgloss.Style
	UserLabel         lipgloss.Style
	ToolLabel         lipgloss.Style
	ErrorLabel        lipgloss.Style
	SystemLabel       lipgloss.Style
	UserMessage       lipgloss.Style
	AssistantMsg      lipgloss.Style
	ToolMessage       lipgloss.Style
	ErrorMessage      lipgloss.Style
	SystemMessage     lipgloss.Style
}

func themeForMode(mode ThemeMode) theme {
	if mode == ThemeDark {
		return darkTheme()
	}
	return lightTheme()
}

func lightTheme() theme {
	return theme{
		Mode:       ThemeLight,
		Background: "#F8FAFC",
		SurfaceAlt: "#EEF2F7",
		InputBg:    "#E4E4E4",
		Border:     "#CBD5E1",
		Text:       "#111827",
		Muted:      "#64748B",
		Title:      "#0F766E",
		User:       "#2563EB",
		Assistant:  "#0F766E",
		Tool:       "#B45309",
		Error:      "#DC2626",
		System:     "#64748B",
	}
}

func darkTheme() theme {
	return theme{
		Mode:       ThemeDark,
		Background: "#111827",
		SurfaceAlt: "#0F172A",
		InputBg:    "#383838",
		Border:     "#475569",
		Text:       "#E5E7EB",
		Muted:      "#94A3B8",
		Title:      "#5EEAD4",
		User:       "#93C5FD",
		Assistant:  "#5EEAD4",
		Tool:       "#FBBF24",
		Error:      "#FCA5A5",
		System:     "#94A3B8",
	}
}

func appStyle(t theme) lipgloss.Style {
	style := lipgloss.NewStyle().Foreground(lipgloss.Color(t.Text))
	if t.Mode == ThemeDark {
		style = style.Background(lipgloss.Color(t.Background))
	}
	return style
}

func (t theme) styles() styles {
	return styles{
		App: appStyle(t),

		Muted: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)),

		Activity: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)).
			Padding(0, 1),

		Header: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.Title)),

		Footer: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)).
			Padding(0, 1),

		Viewport: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)),

		InputBox: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)).
			Background(lipgloss.Color(t.InputBg)).
			Padding(1, 2, 1, 1),

		CommandHint: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)).
			Padding(0, 1),

		InputModeReadonly: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.Muted)).
			Background(lipgloss.Color(t.InputBg)).
			Padding(0, 1),

		InputModeYolo: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.Error)).
			Background(lipgloss.Color(t.InputBg)).
			Padding(0, 1),

		InputModeCommand: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.User)).
			Background(lipgloss.Color(t.InputBg)).
			Padding(0, 1),

		StatusReady: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Assistant)),

		StatusWarn: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Tool)),

		StatusError: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Error)),

		StatusInfo: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.User)),

		Pill: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)).
			Background(lipgloss.Color(t.SurfaceAlt)).
			Padding(0, 1),

		PillAccent: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.Title)).
			Background(lipgloss.Color(t.SurfaceAlt)).
			Padding(0, 1),

		Palette: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)).
			Border(lipgloss.ThickBorder()).
			BorderForeground(lipgloss.Color(t.Border)).
			Padding(0, 2),

		PaletteMatch: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.User)),

		ToolName: lipgloss.NewStyle().
			Bold(true).
			Foreground(lipgloss.Color(t.Tool)),

		ToolKey: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)),

		ToolValue: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)),

		UserLabel:   labelStyle(t.User),
		ToolLabel:   labelStyle(t.Tool),
		ErrorLabel:  labelStyle(t.Error),
		SystemLabel: labelStyle(t.System),

		UserMessage:   bubbleMessageStyle(t.Text, t.SurfaceAlt),
		AssistantMsg:  assistantMessageStyle(t.Text),
		ToolMessage:   messageStyle(t.Text),
		ErrorMessage:  messageStyle(t.Error),
		SystemMessage: lipgloss.NewStyle().Foreground(lipgloss.Color(t.System)).Padding(0, 1),
	}
}

func labelStyle(color string) lipgloss.Style {
	return lipgloss.NewStyle().
		Bold(true).
		Foreground(lipgloss.Color(color))
}

func messageStyle(textColor string) lipgloss.Style {
	return lipgloss.NewStyle().
		Foreground(lipgloss.Color(textColor)).
		Padding(0, 1)
}

func assistantMessageStyle(textColor string) lipgloss.Style {
	return lipgloss.NewStyle().
		Foreground(lipgloss.Color(textColor)).
		Padding(1, 2)
}

func bubbleMessageStyle(textColor, backgroundColor string) lipgloss.Style {
	return lipgloss.NewStyle().
		Foreground(lipgloss.Color(textColor)).
		Background(lipgloss.Color(backgroundColor)).
		Padding(1, 2)
}

func applyTextareaTheme(input *textarea.Model, t theme) {
	focused := textarea.Style{
		Base: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)).
			Background(lipgloss.Color(t.InputBg)),
		CursorLine: lipgloss.NewStyle().
			Background(lipgloss.Color(t.InputBg)),
		Placeholder: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)),
		Prompt: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Muted)),
		Text: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Text)),
		EndOfBuffer: lipgloss.NewStyle().
			Foreground(lipgloss.Color(t.Surface)),
	}
	blurred := focused
	blurred.CursorLine = lipgloss.NewStyle().Background(lipgloss.Color(t.InputBg))

	input.FocusedStyle = focused
	input.BlurredStyle = blurred
}