platforms/apps/heqi_design_system/lib/src/theme.dart

import 'package:flutter/material.dart';

import 'tokens.dart';

/// 共享 Material 3 主题。业务 App 只能选择品牌，不应复制本主题后自行修改。
abstract final class HeqiTheme {
  static ThemeData light(HeqiBrand brand) => _theme(brand, Brightness.light);

  static ThemeData dark(HeqiBrand brand) => _theme(brand, Brightness.dark);

  static ThemeData _theme(HeqiBrand brand, Brightness brightness) {
    final dark = brightness == Brightness.dark;
    final seed = switch (brand) {
      HeqiBrand.consumer => HeqiColors.consumerPrimary,
      HeqiBrand.service => HeqiColors.servicePrimary,
    };
    final darkPrimary = switch (brand) {
      HeqiBrand.consumer => const Color(0xFFAFC6FF),
      HeqiBrand.service => const Color(0xFFC5C0FF),
    };
    final scheme = ColorScheme.fromSeed(
      seedColor: seed,
      brightness: brightness,
      primary: dark ? darkPrimary : seed,
      secondary: dark ? const Color(0xFF86D7B5) : HeqiColors.success,
      error: dark ? const Color(0xFFFFB4AB) : HeqiColors.danger,
      surface: dark ? HeqiColors.darkSurface : Colors.white,
    );
    final textTheme = _textTheme;
    final radius = BorderRadius.circular(HeqiRadius.large);

    return ThemeData(
      brightness: brightness,
      useMaterial3: true,
      colorScheme: scheme,
      scaffoldBackgroundColor: dark
          ? HeqiColors.darkBackground
          : HeqiColors.lightBackground,
      textTheme: textTheme,
      visualDensity: VisualDensity.standard,
      appBarTheme: AppBarTheme(
        backgroundColor: Colors.transparent,
        foregroundColor: scheme.onSurface,
        elevation: 0,
        scrolledUnderElevation: 0,
        centerTitle: false,
        titleTextStyle: textTheme.titleLarge?.copyWith(color: scheme.onSurface),
      ),
      cardTheme: CardThemeData(
        color: scheme.surface,
        elevation: 0,
        margin: EdgeInsets.zero,
        shape: RoundedRectangleBorder(
          borderRadius: radius,
          side: BorderSide(color: scheme.outlineVariant),
        ),
      ),
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: dark ? scheme.surfaceContainerHigh : scheme.surface,
        contentPadding: const EdgeInsets.symmetric(
          horizontal: HeqiSpacing.x4,
          vertical: HeqiSpacing.x4,
        ),
        border: OutlineInputBorder(
          borderRadius: radius,
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: radius,
          borderSide: BorderSide(color: scheme.outlineVariant),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: radius,
          borderSide: BorderSide(color: scheme.primary, width: 2),
        ),
        errorBorder: OutlineInputBorder(
          borderRadius: radius,
          borderSide: BorderSide(color: scheme.error),
        ),
      ),
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size.fromHeight(HeqiSize.buttonHeight),
          shape: RoundedRectangleBorder(borderRadius: radius),
          textStyle: textTheme.labelLarge,
        ),
      ),
      elevatedButtonTheme: ElevatedButtonThemeData(
        style: ElevatedButton.styleFrom(
          minimumSize: const Size.fromHeight(HeqiSize.buttonHeight),
          elevation: 0,
          shape: RoundedRectangleBorder(borderRadius: radius),
          textStyle: textTheme.labelLarge,
        ),
      ),
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size.fromHeight(HeqiSize.buttonHeight),
          shape: RoundedRectangleBorder(borderRadius: radius),
          textStyle: textTheme.labelLarge,
        ),
      ),
      textButtonTheme: TextButtonThemeData(
        style: TextButton.styleFrom(
          minimumSize: const Size.square(HeqiSize.minTouchTarget),
          textStyle: textTheme.labelLarge,
        ),
      ),
      navigationBarTheme: NavigationBarThemeData(
        height: HeqiSize.navigationBarHeight,
        elevation: 0,
        backgroundColor: scheme.surface,
        indicatorColor: scheme.primaryContainer,
        labelTextStyle: WidgetStateProperty.resolveWith(
          (states) => textTheme.labelSmall?.copyWith(
            color: states.contains(WidgetState.selected)
                ? scheme.primary
                : scheme.onSurfaceVariant,
            fontWeight: states.contains(WidgetState.selected)
                ? FontWeight.w700
                : FontWeight.w500,
          ),
        ),
      ),
      chipTheme: ChipThemeData(
        side: BorderSide.none,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(HeqiRadius.small),
        ),
        labelStyle: textTheme.labelSmall,
      ),
      listTileTheme: const ListTileThemeData(
        minTileHeight: 56,
        contentPadding: EdgeInsets.symmetric(
          horizontal: HeqiSpacing.x4,
          vertical: HeqiSpacing.x1,
        ),
      ),
      bottomSheetTheme: BottomSheetThemeData(
        backgroundColor: scheme.surface,
        modalBackgroundColor: scheme.surface,
        showDragHandle: true,
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(
            top: Radius.circular(HeqiRadius.sheet),
          ),
        ),
      ),
      dialogTheme: DialogThemeData(
        backgroundColor: scheme.surface,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(HeqiRadius.sheet),
        ),
      ),
      dividerTheme: DividerThemeData(
        color: scheme.outlineVariant,
        thickness: 1,
        space: 1,
      ),
      snackBarTheme: SnackBarThemeData(
        behavior: SnackBarBehavior.floating,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(HeqiRadius.medium),
        ),
      ),
    );
  }

  static const _textTheme = TextTheme(
    displaySmall: TextStyle(
      fontSize: 32,
      height: 1.25,
      fontWeight: FontWeight.w700,
    ),
    headlineMedium: TextStyle(
      fontSize: 28,
      height: 1.28,
      fontWeight: FontWeight.w700,
    ),
    headlineSmall: TextStyle(
      fontSize: 24,
      height: 1.33,
      fontWeight: FontWeight.w700,
    ),
    titleLarge: TextStyle(
      fontSize: 22,
      height: 1.27,
      fontWeight: FontWeight.w600,
    ),
    titleMedium: TextStyle(
      fontSize: 16,
      height: 1.5,
      fontWeight: FontWeight.w600,
    ),
    bodyLarge: TextStyle(fontSize: 16, height: 1.5),
    bodyMedium: TextStyle(fontSize: 14, height: 1.55),
    labelLarge: TextStyle(
      fontSize: 14,
      height: 1.4,
      fontWeight: FontWeight.w600,
    ),
    labelSmall: TextStyle(
      fontSize: 12,
      height: 1.35,
      fontWeight: FontWeight.w500,
    ),
  );
}