import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';

// ── Colour constants ──────────────────────────────────────────────────────────
//
// Mirrors the web frontend's design system (`docs/design-system.md` in
// fabledscribe). Foundation pass shipped on web 2026-04-27 in `7a9a8b7`;
// this is the equivalent palette swap for Flutter. Per-screen "surface
// phase" reclassification (button Hybrid rule, border audit, etc.) is
// deferred — most widgets read `colorScheme.primary` so the palette flip
// alone covers a large surface.

// Dark mode — Obsidian / Iron / Pewter / Parchment (FabledSword baseline)
const _darkBackground    = Color(0xFF14171A); // Obsidian
const _darkSurface       = Color(0xFF1E2228); // Iron
const _darkSurfaceVar    = Color(0xFF2C313A); // Slate
const _darkPrimary       = Color(0xFF5B4A8A); // dusty violet (Scribe accent)
const _darkPrimaryDeep   = Color(0xFF3F3560); // gradient stop
const _darkOnSurface     = Color(0xFFE8E4D8); // Parchment
const _darkOnSurfaceVar  = Color(0xFFC2BFB4); // Vellum
const _darkOutline       = Color(0xFF3F4651); // Pewter

// Light mode — warm parchment (Scribe iteration)
const _lightBackground   = Color(0xFFF5F1E8); // warm cream page
const _lightSurface      = Color(0xFFFBF8F0); // near-white card
const _lightSurfaceVar   = Color(0xFFEFEAE0); // inset / hover surface
const _lightPrimary      = Color(0xFF5B4A8A); // dusty violet (same on both modes)
const _lightOnSurface    = Color(0xFF14171A); // deep ink (Obsidian inverted)
const _lightOnSurfaceVar = Color(0xFF5A5852); // warm mid grey
const _lightOutline      = Color(0xFFD9D6CE); // warm light pewter

// Semantic — identical across themes
const _semanticError     = Color(0xFFC04A1F); // terracotta — validation/error
const _semanticErrorBg   = Color(0xFF7E2A1F); // Oxblood-hover for dark error container
const _semanticErrorFg   = Color(0xFFFEE2E2); // light text on dark error container

// Action tokens — Hybrid rule per the doc. These don't fit ColorScheme
// natively (Material's primary/secondary/tertiary slots all carry the
// brand accent), so they live on a ThemeExtension exposed below.
const _actionPrimary           = Color(0xFF4A5D3F); // Moss
const _actionPrimaryHover      = Color(0xFF5A6F4D);
const _actionSecondary         = Color(0xFF8B7355); // Bronze
const _actionSecondaryHover    = Color(0xFFA0876A);
const _actionDestructive       = Color(0xFF6B2118); // Oxblood
const _actionDestructiveHover  = Color(0xFF7E2A1F);
const _actionGhostBorder       = Color(0xFF3F4651); // Pewter (same as outline)

// ── Action ThemeExtension ─────────────────────────────────────────────────────
// Read with: Theme.of(context).extension<ActionColors>()!.primary
//
// Flutter's ColorScheme has primary/secondary/tertiary all conceptually
// "branded", whereas the doc's Hybrid rule reserves accent for brand
// moments (Send, empty-state CTAs) and routes action buttons through a
// separate Moss/Bronze/Oxblood/Pewter palette. This extension carries
// those tokens without polluting ColorScheme.

@immutable
class ActionColors extends ThemeExtension<ActionColors> {
  final Color primary;          // Moss — Save / Confirm
  final Color primaryHover;
  final Color secondary;        // Bronze — Cancel / alternate paths
  final Color secondaryHover;
  final Color destructive;      // Oxblood — Delete / irreversible
  final Color destructiveHover;
  final Color ghostBorder;      // Pewter — tertiary / "later" / "skip"

  const ActionColors({
    required this.primary,
    required this.primaryHover,
    required this.secondary,
    required this.secondaryHover,
    required this.destructive,
    required this.destructiveHover,
    required this.ghostBorder,
  });

  static const _kStandard = ActionColors(
    primary:          _actionPrimary,
    primaryHover:     _actionPrimaryHover,
    secondary:        _actionSecondary,
    secondaryHover:   _actionSecondaryHover,
    destructive:      _actionDestructive,
    destructiveHover: _actionDestructiveHover,
    ghostBorder:      _actionGhostBorder,
  );

  @override
  ActionColors copyWith({
    Color? primary,
    Color? primaryHover,
    Color? secondary,
    Color? secondaryHover,
    Color? destructive,
    Color? destructiveHover,
    Color? ghostBorder,
  }) {
    return ActionColors(
      primary:          primary ?? this.primary,
      primaryHover:     primaryHover ?? this.primaryHover,
      secondary:        secondary ?? this.secondary,
      secondaryHover:   secondaryHover ?? this.secondaryHover,
      destructive:      destructive ?? this.destructive,
      destructiveHover: destructiveHover ?? this.destructiveHover,
      ghostBorder:      ghostBorder ?? this.ghostBorder,
    );
  }

  @override
  ActionColors lerp(ThemeExtension<ActionColors>? other, double t) {
    if (other is! ActionColors) return this;
    return ActionColors(
      primary:          Color.lerp(primary, other.primary, t)!,
      primaryHover:     Color.lerp(primaryHover, other.primaryHover, t)!,
      secondary:        Color.lerp(secondary, other.secondary, t)!,
      secondaryHover:   Color.lerp(secondaryHover, other.secondaryHover, t)!,
      destructive:      Color.lerp(destructive, other.destructive, t)!,
      destructiveHover: Color.lerp(destructiveHover, other.destructiveHover, t)!,
      ghostBorder:      Color.lerp(ghostBorder, other.ghostBorder, t)!,
    );
  }
}

// ── Typography ─────────────────────────────────────────────────────────────────
// Inter for body / labels / titleMedium-and-below.
// Fraunces for display / headline / titleLarge — only at ≥18px per the doc.
// JetBrains Mono available via GoogleFonts.jetBrainsMono() at call sites for
// code blocks (Flutter's TextTheme has no dedicated mono slot).

TextTheme _buildTextTheme(TextTheme base) {
  final inter    = GoogleFonts.interTextTheme(base);
  final fraunces = GoogleFonts.frauncesTextTheme(base);
  return inter.copyWith(
    displayLarge:   fraunces.displayLarge,
    displayMedium:  fraunces.displayMedium,
    displaySmall:   fraunces.displaySmall,
    headlineLarge:  fraunces.headlineLarge,
    headlineMedium: fraunces.headlineMedium,
    headlineSmall:  fraunces.headlineSmall,
    titleLarge:     fraunces.titleLarge,
    // titleMedium / titleSmall / body* / label* stay Inter
  );
}

// ── Themes ─────────────────────────────────────────────────────────────────────

ThemeData fabledDarkTheme() {
  final cs = ColorScheme(
    brightness:          Brightness.dark,
    primary:             _darkPrimary,
    onPrimary:           Colors.white,
    primaryContainer:    _darkPrimaryDeep,
    onPrimaryContainer:  _darkOnSurface,
    secondary:           _darkPrimary,
    onSecondary:         Colors.white,
    secondaryContainer:  _darkSurfaceVar,
    onSecondaryContainer: _darkOnSurface,
    tertiary:            _darkPrimary,
    onTertiary:          Colors.white,
    tertiaryContainer:   _darkSurfaceVar,
    onTertiaryContainer: _darkOnSurface,
    error:               _semanticError,
    onError:             Colors.white,
    errorContainer:      _semanticErrorBg,
    onErrorContainer:    _semanticErrorFg,
    surface:             _darkSurface,
    onSurface:           _darkOnSurface,
    surfaceContainerHighest: _darkSurfaceVar,
    onSurfaceVariant:    _darkOnSurfaceVar,
    outline:             _darkOutline,
    outlineVariant:      _darkOutline,
    shadow:              Colors.black,
    scrim:               Colors.black,
    inverseSurface:      _darkOnSurface,
    onInverseSurface:    _darkSurface,
    inversePrimary:      _lightPrimary,
  );

  return ThemeData(
    useMaterial3:   true,
    colorScheme:    cs,
    scaffoldBackgroundColor: _darkBackground,
    textTheme: _buildTextTheme(ThemeData.dark().textTheme),
    extensions: const [ActionColors._kStandard],
    cardTheme: CardThemeData(
      color:         _darkSurface,
      elevation:     2,
      shadowColor:   Colors.black.withValues(alpha: 0.4),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(14)),
    ),
    navigationBarTheme: NavigationBarThemeData(
      backgroundColor: _darkSurface,
      indicatorColor:  _darkPrimary.withValues(alpha: 0.2),
    ),
    navigationRailTheme: NavigationRailThemeData(
      backgroundColor: _darkSurface,
      indicatorColor:  _darkPrimary.withValues(alpha: 0.2),
    ),
    inputDecorationTheme: InputDecorationTheme(
      filled:      true,
      fillColor:   _darkSurfaceVar,
      border: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _darkOutline),
      ),
      enabledBorder: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _darkOutline),
      ),
      focusedBorder: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _darkPrimary, width: 2),
      ),
    ),
    dividerTheme: DividerThemeData(color: _darkOutline, thickness: 1),
    chipTheme: ChipThemeData(
      backgroundColor: _darkSurfaceVar,
      labelStyle: TextStyle(color: _darkOnSurfaceVar, fontSize: 12),
      side: BorderSide(color: _darkOutline),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
    ),
  );
}

ThemeData fabledLightTheme() {
  final cs = ColorScheme(
    brightness:          Brightness.light,
    primary:             _lightPrimary,
    onPrimary:           Colors.white,
    // Warm parchment-tinted primary container, replacing the prior cool
    // indigo `#EDE5FF`. Used for chip/badge backgrounds at low alpha.
    primaryContainer:    const Color(0xFFEDE9F4),
    onPrimaryContainer:  _lightOnSurface,
    secondary:           _lightPrimary,
    onSecondary:         Colors.white,
    secondaryContainer:  _lightSurfaceVar,
    onSecondaryContainer: _lightOnSurface,
    tertiary:            _lightPrimary,
    onTertiary:          Colors.white,
    tertiaryContainer:   _lightSurfaceVar,
    onTertiaryContainer: _lightOnSurface,
    error:               _semanticError,
    onError:             Colors.white,
    errorContainer:      const Color(0xFFFEE2E2),
    onErrorContainer:    _semanticErrorBg,
    surface:             _lightSurface,
    onSurface:           _lightOnSurface,
    surfaceContainerHighest: _lightSurfaceVar,
    onSurfaceVariant:    _lightOnSurfaceVar,
    outline:             _lightOutline,
    outlineVariant:      _lightOutline,
    shadow:              Colors.black,
    scrim:               Colors.black,
    inverseSurface:      _lightOnSurface,
    onInverseSurface:    _lightSurface,
    inversePrimary:      _darkPrimary,
  );

  return ThemeData(
    useMaterial3:   true,
    colorScheme:    cs,
    scaffoldBackgroundColor: _lightBackground,
    textTheme: _buildTextTheme(ThemeData.light().textTheme),
    extensions: const [ActionColors._kStandard],
    cardTheme: CardThemeData(
      color:         _lightSurface,
      elevation:     1,
      shadowColor:   Colors.black.withValues(alpha: 0.08),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(14)),
    ),
    navigationBarTheme: NavigationBarThemeData(
      backgroundColor: _lightSurface,
      indicatorColor:  _lightPrimary.withValues(alpha: 0.12),
    ),
    navigationRailTheme: NavigationRailThemeData(
      backgroundColor: _lightSurface,
      indicatorColor:  _lightPrimary.withValues(alpha: 0.12),
    ),
    inputDecorationTheme: InputDecorationTheme(
      filled:      true,
      fillColor:   _lightSurfaceVar,
      border: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _lightOutline),
      ),
      enabledBorder: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _lightOutline),
      ),
      focusedBorder: OutlineInputBorder(
        borderRadius: BorderRadius.circular(24),
        borderSide: BorderSide(color: _lightPrimary, width: 2),
      ),
    ),
    dividerTheme: DividerThemeData(color: _lightOutline, thickness: 1),
    chipTheme: ChipThemeData(
      backgroundColor: _lightSurfaceVar,
      labelStyle: TextStyle(color: _lightOnSurfaceVar, fontSize: 12),
      side: BorderSide(color: _lightOutline),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
    ),
  );
}

// ── GradientButton ─────────────────────────────────────────────────────────────
// Brand-moment CTA equivalent of the web's `--gradient-cta` — chat send,
// journal send, primary "Scribe-feature" actions. Reserve for those moments
// per the doc's Hybrid rule; use FilledButton with ActionColors.primary
// (Moss) for everything else.

class GradientButton extends StatelessWidget {
  final VoidCallback? onPressed;
  final Widget child;
  final EdgeInsetsGeometry padding;

  const GradientButton({
    super.key,
    required this.onPressed,
    required this.child,
    this.padding = const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
  });

  @override
  Widget build(BuildContext context) {
    final disabled = onPressed == null;
    return AnimatedOpacity(
      opacity: disabled ? 0.45 : 1.0,
      duration: const Duration(milliseconds: 150),
      child: DecoratedBox(
        decoration: BoxDecoration(
          gradient: disabled
              ? null
              : const LinearGradient(
                  begin: Alignment.topLeft,
                  end: Alignment.bottomRight,
                  colors: [_darkPrimary, _darkPrimaryDeep],
                ),
          color: disabled ? _darkPrimary : null,
          borderRadius: BorderRadius.circular(12),
          boxShadow: disabled
              ? null
              : [
                  BoxShadow(
                    color: _darkPrimary.withValues(alpha: 0.45),
                    blurRadius: 8,
                    offset: const Offset(0, 3),
                  ),
                ],
        ),
        child: Material(
          color: Colors.transparent,
          child: InkWell(
            onTap: onPressed,
            borderRadius: BorderRadius.circular(12),
            child: Padding(padding: padding, child: child),
          ),
        ),
      ),
    );
  }
}