package theme

import (
	"fmt"
	"os"
	"sync"

	"github.com/charmbracelet/lipgloss"
)

// ColorScheme defines the color palette for the theme
type ColorScheme struct {
	Primary    lipgloss.Color
	Success    lipgloss.Color
	Warning    lipgloss.Color
	Error      lipgloss.Color
	Muted      lipgloss.Color
	Background lipgloss.Color
}

// Theme represents a color theme with its name and color scheme
type Theme struct {
	Name   string
	Scheme ColorScheme
}

// Global variables for current theme and styles
var (
	currentTheme *Theme
	once         sync.Once

	// Global styles that can be used throughout the application
	StylePrimary  lipgloss.Style
	StyleSuccess  lipgloss.Style
	StyleWarning  lipgloss.Style
	StyleError    lipgloss.Style
	StyleMuted    lipgloss.Style
	StyleTitle    lipgloss.Style
	StyleSubtitle lipgloss.Style
	StyleHelpKey  lipgloss.Style
)

// DefaultTheme is the standard blue-based theme
var DefaultTheme = &Theme{
	Name: "default",
	Scheme: ColorScheme{
		Primary:    lipgloss.Color("62"),  // Blue
		Success:    lipgloss.Color("46"),  // Green
		Warning:    lipgloss.Color("208"), // Orange
		Error:      lipgloss.Color("196"), // Red
		Muted:      lipgloss.Color("241"), // Gray
		Background: lipgloss.Color(""),    // Default terminal background
	},
}

// DarkTheme is a purple-based dark theme
var DarkTheme = &Theme{
	Name: "dark",
	Scheme: ColorScheme{
		Primary:    lipgloss.Color("141"), // Purple
		Success:    lipgloss.Color("51"),  // Cyan
		Warning:    lipgloss.Color("226"), // Yellow
		Error:      lipgloss.Color("196"), // Red
		Muted:      lipgloss.Color("245"), // Light gray
		Background: lipgloss.Color(""),    // Default terminal background
	},
}

// LightTheme is a green-based light theme
var LightTheme = &Theme{
	Name: "light",
	Scheme: ColorScheme{
		Primary:    lipgloss.Color("34"),  // Green
		Success:    lipgloss.Color("36"),  // Teal
		Warning:    lipgloss.Color("214"), // Amber
		Error:      lipgloss.Color("196"), // Red
		Muted:      lipgloss.Color("244"), // Gray
		Background: lipgloss.Color(""),    // Default terminal background
	},
}

// DraculaTheme is the popular Dracula dark color scheme
var DraculaTheme = &Theme{
	Name: "dracula",
	Scheme: ColorScheme{
		Primary:    lipgloss.Color("#BD93F9"), // Purple
		Success:    lipgloss.Color("#50FA7B"), // Green
		Warning:    lipgloss.Color("#FFB86C"), // Orange
		Error:      lipgloss.Color("#FF5555"), // Red
		Muted:      lipgloss.Color("#6272A4"), // Light purple-gray
		Background: lipgloss.Color("#282A36"), // Dark background
	},
}

// EverforestTheme is the natural Everforest dark color scheme
var EverforestTheme = &Theme{
	Name: "everforest",
	Scheme: ColorScheme{
		Primary:    lipgloss.Color("#7fbbb3"), // Blue
		Success:    lipgloss.Color("#a7c080"), // Green
		Warning:    lipgloss.Color("#dbbc7f"), // Yellow
		Error:      lipgloss.Color("#e67e80"), // Red
		Muted:      lipgloss.Color("#414b50"), // Gray
		Background: lipgloss.Color("#272e33"), // Dark background
	},
}

// ThemeRegistry holds all available themes
var ThemeRegistry = map[string]*Theme{
	"default":    DefaultTheme,
	"dark":       DarkTheme,
	"light":      LightTheme,
	"dracula":    DraculaTheme,
	"everforest": EverforestTheme,
}

// GetTheme loads the theme from config or environment variable
// Returns the default theme if no theme is specified
func GetTheme() (*Theme, error) {
	once.Do(func() {
		// Try to get theme from environment variable first
		themeName := os.Getenv("THEME")
		if themeName == "" {
			themeName = "everforest"
		}

		// Look up the theme in the registry
		if theme, ok := ThemeRegistry[themeName]; ok {
			currentTheme = theme
		} else {
			// If theme not found, use everforest as default
			currentTheme = EverforestTheme
		}

		// Apply the theme to initialize styles
		ApplyTheme(currentTheme)
	})

	return currentTheme, nil
}

// ApplyTheme applies the given theme to all global styles
func ApplyTheme(theme *Theme) {
	currentTheme = theme

	// Primary style
	StylePrimary = lipgloss.NewStyle().
		Foreground(theme.Scheme.Primary)

	// Success style
	StyleSuccess = lipgloss.NewStyle().
		Foreground(theme.Scheme.Success)

	// Warning style
	StyleWarning = lipgloss.NewStyle().
		Foreground(theme.Scheme.Warning)

	// Error style
	StyleError = lipgloss.NewStyle().
		Foreground(theme.Scheme.Error)

	// Muted style
	StyleMuted = lipgloss.NewStyle().
		Foreground(theme.Scheme.Muted)

	// Title style (bold primary)
	StyleTitle = lipgloss.NewStyle().
		Foreground(theme.Scheme.Primary).
		Bold(true)

	// Subtitle style (muted)
	StyleSubtitle = lipgloss.NewStyle().
		Foreground(theme.Scheme.Muted)

	// Help key style (bold primary, slightly different shade)
	StyleHelpKey = lipgloss.NewStyle().
		Foreground(theme.Scheme.Primary).
		Bold(true)
}

// GetThemeNames returns a list of available theme names
func GetThemeNames() []string {
	names := make([]string, 0, len(ThemeRegistry))
	for name := range ThemeRegistry {
		names = append(names, name)
	}
	return names
}

// SetTheme changes the current theme by name
func SetTheme(name string) error {
	theme, ok := ThemeRegistry[name]
	if !ok {
		return fmt.Errorf("theme '%s' not found. Available themes: %v", name, GetThemeNames())
	}

	ApplyTheme(theme)
	return nil
}

// GetCurrentTheme returns the currently active theme
func GetCurrentTheme() *Theme {
	if currentTheme == nil {
		currentTheme = DefaultTheme
		ApplyTheme(currentTheme)
	}
	return currentTheme
}

// GetColorScheme returns the color scheme of the current theme
func GetColorScheme() ColorScheme {
	return GetCurrentTheme().Scheme
}