package theme

import (
	"context"
	"fmt"
	"math"
	"strings"

	"github.com/bnema/dumber/internal/domain/entity"
	"github.com/bnema/dumber/internal/logging"
	"github.com/bnema/puregotk/v4/gdk"
	"github.com/bnema/puregotk/v4/gtk"
)

// Manager handles theme state and CSS application.
// Theme precedence and fallback are resolved before data reaches this adapter.
type Manager struct {
	prefersDark          bool    // Resolved dark mode preference
	lightPalette         Palette // Light theme colors
	darkPalette          Palette // Dark theme colors
	uiScale              float64 // UI scaling factor (1.0 = 100%)
	fonts                FontConfig
	gtkFont              string
	modeColors           ModeColors // Modal mode indicator colors
	transitionDurationMs int
	cssProvider          *gtk.CssProvider
	appliedFont          string
}

// NewManager creates a new theme manager from an already-resolved theme.
func NewManager(ctx context.Context, resolved entity.ResolvedTheme) *Manager {
	log := logging.FromContext(ctx)

	m := &Manager{transitionDurationMs: defaultTransitionDurationMs}
	m.applyResolvedTheme(resolved)

	log.Debug().
		Bool("prefers_dark", m.prefersDark).
		Float64("ui_scale", m.uiScale).
		Str("sans_font", m.fonts.SansFont).
		Str("monospace_font", m.fonts.MonospaceFont).
		Str("gtk_font", m.gtkFont).
		Msg("theme manager initialized")

	return m
}

func (m *Manager) applyResolvedTheme(resolved entity.ResolvedTheme) {
	m.prefersDark = resolved.PrefersDark
	m.lightPalette = PaletteFromEntity(resolved.LightPalette, false)
	m.darkPalette = PaletteFromEntity(resolved.DarkPalette, true)
	m.uiScale = resolved.UIScale
	if m.uiScale <= 0 {
		m.uiScale = 1.0
	}
	m.fonts = FontConfigFromEntity(resolved.Fonts)
	if m.fonts.GtkFont == "" {
		m.fonts.GtkFont = DefaultGTKFont()
	}
	m.gtkFont = m.fonts.GtkFont
	m.modeColors = ModeColorsFromEntity(resolved.ModeColors)
}

// SetTransitionDuration sets the CSS transition duration used for theme-driven
// animations such as Vim mode pulse timing.
func (m *Manager) SetTransitionDuration(ms int) {
	if ms < 0 {
		ms = defaultTransitionDurationMs
	}
	m.transitionDurationMs = ms
}

// PrefersDark returns true if dark mode is active.
func (m *Manager) PrefersDark() bool {
	return m.prefersDark
}

// GetCurrentPalette returns the active palette based on current preference.
func (m *Manager) GetCurrentPalette() Palette {
	if m.prefersDark {
		return m.darkPalette
	}
	return m.lightPalette
}

// GetBackgroundRGBA returns the current theme's background color as RGBA float32 values.
// Used to set WebView background color to eliminate white flash during loading.
func (m *Manager) GetBackgroundRGBA() (r, g, b, a float32) {
	palette := m.GetCurrentPalette()
	return HexToRGBA(palette.Background)
}

// GetLightPalette returns the light theme palette.
func (m *Manager) GetLightPalette() Palette {
	return m.lightPalette
}

// GetDarkPalette returns the dark theme palette.
func (m *Manager) GetDarkPalette() Palette {
	return m.darkPalette
}

// GetModeColors returns the modal mode indicator colors.
func (m *Manager) GetModeColors() ModeColors {
	return m.modeColors
}

// GetWebUIThemeCSS returns CSS text that defines both light and dark variables.
// WebUI uses `:root` for light and `.dark` overrides for dark.
func (m *Manager) GetWebUIThemeCSS() string {
	lightVars := m.lightPalette.ToWebCSSVars()
	darkVars := m.darkPalette.ToWebCSSVars()
	return fmt.Sprintf(":root{\n%s}\n\n.dark{\n%s}\n", lightVars, darkVars)
}

const gtkDefaultFontPointSize = 11

func DefaultGTKFont() string { return "Adwaita Sans" }

func formatGTKFontName(family string, uiScale float64) string {
	family = strings.TrimSpace(family)
	if family == "" {
		family = DefaultGTKFont()
	}
	if uiScale <= 0 {
		uiScale = 1.0
	}
	size := int(math.Round(gtkDefaultFontPointSize * uiScale))
	if size < 1 {
		size = gtkDefaultFontPointSize
	}
	return fmt.Sprintf("%s %d", family, size)
}

func shouldApplyGTKFontName(current, next string) bool {
	return next != "" && next != current
}

// ApplyToDisplay loads the theme CSS into the display.
func (m *Manager) ApplyToDisplay(ctx context.Context, display *gdk.Display) {
	log := logging.FromContext(ctx)

	if display == nil {
		log.Warn().Msg("cannot apply theme: display is nil")
		return
	}

	// Generate CSS with current palette, UI scale, fonts, mode colors, and the
	// configured transition duration.
	palette := m.GetCurrentPalette()
	css := GenerateCSSFullWithTiming(palette, m.uiScale, m.fonts, m.modeColors, m.transitionDurationMs)
	fontName := formatGTKFontName(m.gtkFont, m.uiScale)

	settings := gtk.SettingsGetForDisplay(display)
	if settings == nil {
		log.Warn().Msg("cannot apply theme font scaling: settings unavailable")
	} else if shouldApplyGTKFontName(m.appliedFont, fontName) {
		settings.SetPropertyGtkFontName(fontName)
		m.appliedFont = fontName
		settings.Unref()
	} else {
		settings.Unref()
	}

	// Create CSS provider if needed
	if m.cssProvider == nil {
		m.cssProvider = gtk.NewCssProvider()
	}

	if m.cssProvider == nil {
		log.Error().Msg("failed to create CSS provider")
		return
	}

	// Load CSS
	m.cssProvider.LoadFromString(css)
	gtk.StyleContextAddProviderForDisplay(
		display,
		m.cssProvider,
		uint(gtk.STYLE_PROVIDER_PRIORITY_APPLICATION),
	)

	log.Debug().
		Bool("dark_mode", m.prefersDark).
		Msg("theme CSS applied to display")
}

// UpdateFromResolved updates the theme manager state from a resolved theme.
func (m *Manager) UpdateFromResolved(ctx context.Context, resolved entity.ResolvedTheme, display *gdk.Display) {
	log := logging.FromContext(ctx)

	m.applyResolvedTheme(resolved)

	log.Info().
		Bool("prefers_dark", m.prefersDark).
		Float64("ui_scale", m.uiScale).
		Str("sans_font", m.fonts.SansFont).
		Str("monospace_font", m.fonts.MonospaceFont).
		Str("gtk_font", m.gtkFont).
		Msg("theme manager updated from resolved theme")

	// Re-apply CSS if display is available
	if display != nil {
		m.ApplyToDisplay(ctx, display)
	}
}