BadNote/lib/theme/app_theme.dart

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

/// BadNote design tokens — ink-desk academic aesthetic.
/// Warm paper field, graphite ink, single copper accent. No Inter / no purple.
abstract final class AppTokens {
  static const Color paper = Color(0xFFF3EDE3);
  static const Color paperDark = Color(0xFF1C1A17);
  static const Color ink = Color(0xFF1F1B16);
  static const Color inkMuted = Color(0xFF6B6358);
  static const Color rule = Color(0xFFD9CFC0);
  static const Color copper = Color(0xFFB45A2A);
  static const Color copperSoft = Color(0xFFE8C4AE);
  static const Color sticky = Color(0xFFF6E7A5);

  static const double radiusSm = 6;
  static const double radiusMd = 12;
  static const double chromePad = 16;
}

abstract final class AppTheme {
  static ThemeData light() {
    final base = ColorScheme.fromSeed(
      seedColor: AppTokens.copper,
      brightness: Brightness.light,
      surface: AppTokens.paper,
      primary: AppTokens.copper,
      onPrimary: Colors.white,
      onSurface: AppTokens.ink,
      secondary: AppTokens.inkMuted,
    );
    return _build(base, Brightness.light);
  }

  static ThemeData dark() {
    final base = ColorScheme.fromSeed(
      seedColor: AppTokens.copperSoft,
      brightness: Brightness.dark,
      surface: AppTokens.paperDark,
      primary: AppTokens.copperSoft,
      onSurface: AppTokens.paper,
    );
    return _build(base, Brightness.dark);
  }

  static ThemeData fromScheme(ColorScheme scheme) =>
      _build(scheme, scheme.brightness);

  static ThemeData _build(ColorScheme scheme, Brightness brightness) {
    final display = GoogleFonts.sourceSerif4TextTheme(
      ThemeData(brightness: brightness).textTheme,
    );
    final ui = GoogleFonts.ibmPlexSansTextTheme(
      ThemeData(brightness: brightness).textTheme,
    );
    final merged = ui.copyWith(
      displayLarge: display.displayLarge?.copyWith(fontWeight: FontWeight.w600),
      displayMedium: display.displayMedium?.copyWith(fontWeight: FontWeight.w600),
      displaySmall: display.displaySmall?.copyWith(fontWeight: FontWeight.w600),
      headlineLarge: display.headlineLarge?.copyWith(fontWeight: FontWeight.w600),
      headlineMedium: display.headlineMedium?.copyWith(fontWeight: FontWeight.w600),
      headlineSmall: display.headlineSmall?.copyWith(fontWeight: FontWeight.w600),
      titleLarge: display.titleLarge?.copyWith(fontWeight: FontWeight.w600),
    );

    return ThemeData(
      useMaterial3: true,
      colorScheme: scheme,
      scaffoldBackgroundColor: scheme.surface,
      textTheme: merged,
      appBarTheme: AppBarTheme(
        centerTitle: false,
        backgroundColor: scheme.surface,
        foregroundColor: scheme.onSurface,
        elevation: 0,
        scrolledUnderElevation: 0.5,
        titleTextStyle: display.titleLarge?.copyWith(
          color: scheme.onSurface,
          fontWeight: FontWeight.w600,
        ),
      ),
      navigationBarTheme: NavigationBarThemeData(
        backgroundColor: scheme.surface,
        indicatorColor: AppTokens.copper.withValues(alpha: 0.18),
        labelTextStyle: WidgetStatePropertyAll(
          ui.labelMedium?.copyWith(fontWeight: FontWeight.w600),
        ),
      ),
      navigationRailTheme: NavigationRailThemeData(
        backgroundColor: scheme.surface,
        indicatorColor: AppTokens.copper.withValues(alpha: 0.18),
        selectedIconTheme: IconThemeData(color: scheme.primary),
        unselectedIconTheme: IconThemeData(color: scheme.onSurfaceVariant),
      ),
      cardTheme: CardThemeData(
        color: scheme.surface,
        elevation: 0,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(AppTokens.radiusMd),
          side: BorderSide(color: AppTokens.rule.withValues(alpha: 0.7)),
        ),
      ),
      dividerColor: AppTokens.rule,
      floatingActionButtonTheme: FloatingActionButtonThemeData(
        backgroundColor: scheme.primary,
        foregroundColor: scheme.onPrimary,
      ),
    );
  }
}