import 'package:flutter/material.dart';

/// 语义色 token（ADR-005：以 AI宠物_iOS_UI设计稿.html 珊瑚橙暖色系为品牌正典，
/// 详见 iteration-1-reports/04-ui-login-design-spec.md §1.1）。
abstract final class AppColors {
  /// 品牌珊瑚橙：图标、装饰、渐变起点；不用于承载文字的实心填充（对比度不足）。
  static const primary = Color(0xFFFF6F4C);

  /// 加深珊瑚：实心按钮填充、可点击文字链接（白字约 4.5:1，WCAG AA）。
  static const primaryStrong = Color(0xFFD6431A);

  /// 浅色底上的强调文字、按钮反白替代。
  static const primaryDark = Color(0xFF7A2E12);

  /// amber：渐变终点、徽章、会员/促销 CTA。
  static const accent = Color(0xFFFFB648);

  /// amber 底上的文字。
  static const accentDark = Color(0xFF7A4B0A);

  /// 页面背景（奶油底）。
  static const canvas = Color(0xFFFFF7ED);

  /// 卡片、输入框背景。
  static const surface = Color(0xFFFFFFFF);

  /// peach：图标底、占位块、选中指示。
  static const surfaceTint = Color(0xFFFFE8D6);

  /// 主文字。
  static const ink = Color(0xFF3E2A1F);

  /// 次级文字、占位符。
  static const muted = Color(0xFF9C8977);

  /// 描边、分隔线。
  static const border = Color(0xFFF0DCC8);

  /// sage：成功提示的图标/描边。
  static const success = Color(0xFF7FA88A);

  /// 成功提示底上的文字。
  static const successInk = Color(0xFF3F5744);

  /// 成功提示底色。
  static const successSurface = Color(0xFFE8F0E8);

  static const warning = Color(0xFFF59E0B);

  /// 校验错误文字、错误描边、失败提示（白底上约 5.4:1，AA 达标）。
  static const error = Color(0xFFD0342C);

  /// 品牌渐变：hero 区、头像环、装饰性大面积（不承载正文文字）。
  static const brandGradient = LinearGradient(
    begin: Alignment.topLeft,
    end: Alignment.bottomRight,
    colors: [primary, accent],
  );
}

/// 圆角 token（设计规范 §1.3）。
abstract final class AppRadius {
  /// 小按钮、内嵌 CTA、错误横幅。
  static const sm = 12.0;

  /// 主按钮、SnackBar、菜单组。
  static const md = 16.0;

  /// 输入框、feed 卡。
  static const lg = 18.0;

  /// 大卡片。
  static const xl = 24.0;

  /// 芯片、徽章。
  static const pill = 999.0;
}

ThemeData buildAppTheme() {
  final scheme = ColorScheme.fromSeed(
    seedColor: AppColors.primary,
    brightness: Brightness.light,
    surface: AppColors.surface,
  ).copyWith(error: AppColors.error, onError: Colors.white);

  return ThemeData(
    useMaterial3: true,
    colorScheme: scheme,
    scaffoldBackgroundColor: AppColors.canvas,
    fontFamilyFallback: const [
      'Noto Sans CJK SC',
      'Noto Sans SC',
      'PingFang SC',
      'Microsoft YaHei',
      'sans-serif',
    ],
    textTheme: const TextTheme(
      headlineSmall: TextStyle(
        color: AppColors.ink,
        fontSize: 22,
        fontWeight: FontWeight.w800,
      ),
      titleLarge: TextStyle(
        color: AppColors.ink,
        fontSize: 18,
        fontWeight: FontWeight.w800,
      ),
      titleMedium: TextStyle(
        color: AppColors.ink,
        fontSize: 15,
        fontWeight: FontWeight.w700,
      ),
      bodyMedium: TextStyle(color: AppColors.ink, fontSize: 14, height: 1.5),
      bodySmall: TextStyle(color: AppColors.muted, fontSize: 12, height: 1.4),
    ),
    cardTheme: const CardThemeData(
      color: AppColors.surface,
      elevation: 0,
      margin: EdgeInsets.zero,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.xl)),
        side: BorderSide(color: AppColors.border),
      ),
    ),
    filledButtonTheme: FilledButtonThemeData(
      style: FilledButton.styleFrom(
        backgroundColor: AppColors.primaryStrong,
        foregroundColor: Colors.white,
        disabledBackgroundColor: AppColors.ink.withAlpha(31),
        disabledForegroundColor: AppColors.ink.withAlpha(97),
        minimumSize: const Size(64, 52),
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.all(Radius.circular(AppRadius.md)),
        ),
        textStyle: const TextStyle(fontSize: 15, fontWeight: FontWeight.w700),
      ),
    ),
    inputDecorationTheme: const InputDecorationTheme(
      filled: true,
      fillColor: AppColors.surface,
      contentPadding: EdgeInsets.symmetric(horizontal: 16, vertical: 14),
      border: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.lg)),
        borderSide: BorderSide(color: AppColors.border),
      ),
      enabledBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.lg)),
        borderSide: BorderSide(color: AppColors.border),
      ),
      focusedBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.lg)),
        borderSide: BorderSide(color: AppColors.primary, width: 1.5),
      ),
      errorBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.lg)),
        borderSide: BorderSide(color: AppColors.error, width: 1.5),
      ),
      focusedErrorBorder: OutlineInputBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.lg)),
        borderSide: BorderSide(color: AppColors.error, width: 1.5),
      ),
      errorStyle: TextStyle(color: AppColors.error, fontSize: 12),
      helperStyle: TextStyle(color: AppColors.muted, fontSize: 12),
    ),
    snackBarTheme: const SnackBarThemeData(
      behavior: SnackBarBehavior.floating,
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.all(Radius.circular(AppRadius.md)),
      ),
    ),
    navigationBarTheme: NavigationBarThemeData(
      backgroundColor: AppColors.surface,
      indicatorColor: AppColors.surfaceTint,
      height: 72,
      labelTextStyle: WidgetStateProperty.resolveWith((states) {
        return TextStyle(
          fontSize: 11,
          fontWeight: states.contains(WidgetState.selected)
              ? FontWeight.w700
              : FontWeight.w500,
          color: states.contains(WidgetState.selected)
              ? AppColors.primaryStrong
              : AppColors.muted,
        );
      }),
    ),
  );
}