/// UI-01 主题（视觉规范 §3.1 精确落地）。
///
/// 浅色基准：primary #1A73E8 / surface #FFFFFF / 页面背景 #F6F8FB /
/// 主文字 #172033 / 次文字 #5E6878 / 分隔线 #E5EAF1；等待色 #996300 承载
/// ColorScheme.secondary、错误 #B42318 承载 error。成功色**不进**
/// ColorScheme（Material 无该语义角色），以独立令牌提供（见 ui/tokens.dart，
/// 成功/等待/错误均另有深色提亮变体）。
///
/// 深色：语义对应色（深表面 + 浅文字 + 提亮的主色/等待色/错误色）；图片
/// 与内容不做反色处理，沿用跟随系统的深浅色切换。容器色（secondary/
/// primaryContainer 等）由种子色派生，与 #1A73E8 同系。
///
/// 字阶（fontSize 走 TextScaler，随系统字体缩放；UI-03 §3 校准）：24
/// 页面标题 / 17 分组标题 / 16-14 正文 / 13-12 辅助。组件：主按钮高 48
/// （区间 48-52）、输入框与按钮圆角 12、卡片圆角 16、Dialog 圆角 16、
/// BottomSheet 顶部圆角 16。动效时长常量见 ui/tokens.dart。
library;

import 'package:flutter/material.dart';

import '../ui/tokens.dart';

abstract final class AppTheme {
  /// Material 种子色（容器色派生基准）。
  static const Color seedColor = Color(0xFF1A73E8);

  // ── 浅色基准值（方案 §3.1）──────────────────────────────────────────

  static const Color _primary = Color(0xFF1A73E8);
  static const Color _onPrimary = Color(0xFFFFFFFF);
  static const Color _surface = Color(0xFFFFFFFF);
  static const Color _onSurface = Color(0xFF172033);
  static const Color _background = Color(0xFFF6F8FB);
  static const Color _textSecondary = Color(0xFF69778E); // UI06: app-preview --muted
  static const Color _divider = Color(0xFFE5EAF1);
  static const Color _waiting = Color(0xFF996300);
  static const Color _onWaiting = Color(0xFFFFFFFF);
  static const Color _error = Color(0xFFB42318);

  // ── 深色对应语义值（同语义、深色表面提亮）──────────────────────────

  static const Color _primaryDark = Color(0xFF8AB4F8);
  static const Color _onPrimaryDark = Color(0xFF0B2E6F);
  static const Color _surfaceDark = Color(0xFF1F2530);
  static const Color _onSurfaceDark = Color(0xFFE6EAF2);
  static const Color _backgroundDark = Color(0xFF12161D);
  static const Color _textSecondaryDark = Color(0xFFA6B0C0);
  static const Color _dividerDark = Color(0xFF333B47);
  static const Color _waitingDark = Color(0xFFFCD34D);
  static const Color _onWaitingDark = Color(0xFF402E00);
  static const Color _errorDark = Color(0xFFF87171);
  static const Color _onErrorDark = Color(0xFF5C1A15);

  static ThemeData get light => _build(Brightness.light);
  static ThemeData get dark => _build(Brightness.dark);

  static ThemeData _build(Brightness brightness) {
    final dark = brightness == Brightness.dark;
    final colorScheme =
        ColorScheme.fromSeed(
          seedColor: seedColor,
          brightness: brightness,
        ).copyWith(
          primary: dark ? _primaryDark : _primary,
          onPrimary: dark ? _onPrimaryDark : _onPrimary,
          secondary: dark ? _waitingDark : _waiting,
          onSecondary: dark ? _onWaitingDark : _onWaiting,
          error: dark ? _errorDark : _error,
          onError: dark ? _onErrorDark : Colors.white,
          surface: dark ? _surfaceDark : _surface,
          onSurface: dark ? _onSurfaceDark : _onSurface,
          surfaceContainerHighest: dark ? _dividerDark : _divider,
          onSurfaceVariant: dark ? _textSecondaryDark : _textSecondary,
        );

    final textTheme = _textTheme(colorScheme);
    final buttonBorder = RoundedRectangleBorder(
      borderRadius: BorderRadius.circular(kRadiusInput),
    );

    return ThemeData(
      brightness: brightness,
      colorScheme: colorScheme,
      scaffoldBackgroundColor: dark ? _backgroundDark : _background,
      textTheme: textTheme,

      // AppBar：干净（零海拔 + 页面背景同色），标题用 titleLarge。
      appBarTheme: AppBarTheme(
        backgroundColor: dark ? _backgroundDark : _background,
        surfaceTintColor: Colors.transparent,
        foregroundColor: colorScheme.onSurface,
        titleTextStyle: textTheme.titleLarge,
        elevation: 0,
        scrolledUnderElevation: 1,
        centerTitle: false,
      ),

      // 按钮：主/次操作统一高 48（规格 48-52）、圆角 12。
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size(64, 48),
          shape: buttonBorder,
        ),
      ),
      elevatedButtonTheme: ElevatedButtonThemeData(
        style: ElevatedButton.styleFrom(
          minimumSize: const Size(64, 48),
          shape: buttonBorder,
        ),
      ),
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size(48, 48),
          shape: buttonBorder,
        ),
      ),
      textButtonTheme: TextButtonThemeData(
        style: TextButton.styleFrom(
          minimumSize: const Size(48, 48),
          shape: buttonBorder,
        ),
      ),

      // 输入框：圆角 12，轻分隔线边框，聚焦主色 2px。
      inputDecorationTheme: InputDecorationTheme(
        border: _inputBorder(colorScheme, colorScheme.outline),
        enabledBorder: _inputBorder(
          colorScheme,
          dark ? _dividerDark : _divider,
        ),
        focusedBorder: _inputBorder(colorScheme, colorScheme.primary, width: 2),
        errorBorder: _inputBorder(colorScheme, colorScheme.error),
        focusedErrorBorder: _inputBorder(
          colorScheme,
          colorScheme.error,
          width: 2,
        ),
        contentPadding: const EdgeInsets.symmetric(
          horizontal: kSpace16,
          vertical: kSpace12,
        ),
      ),

      // 卡片：白色表面、圆角 16、细边框无阴影（app-preview .card 形态）。
      cardTheme: CardThemeData(
        color: colorScheme.surface,
        surfaceTintColor: Colors.transparent,
        elevation: 0,
        shadowColor: Colors.transparent,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(kRadiusCard),
          side: BorderSide(color: dark ? _dividerDark : kColorCardBorder),
        ),
      ),

      // Dialog 圆角 16；BottomSheet 仅顶部圆角 16。
      dialogTheme: DialogThemeData(
        surfaceTintColor: Colors.transparent,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(kRadiusCard),
        ),
      ),
      bottomSheetTheme: BottomSheetThemeData(
        backgroundColor: colorScheme.surface,
        surfaceTintColor: Colors.transparent,
        shape: const RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(
            top: Radius.circular(kRadiusCard),
          ),
        ),
      ),

      // Snackbar：浮动 + inverseSurface（自动随深浅色），动作色 inversePrimary。
      snackBarTheme: SnackBarThemeData(
        behavior: SnackBarBehavior.floating,
        backgroundColor: colorScheme.inverseSurface,
        contentTextStyle: textTheme.bodyMedium?.copyWith(
          color: colorScheme.onInverseSurface,
        ),
        actionTextColor: colorScheme.inversePrimary,
      ),

      // 底部导航（app-preview .nav）：白底 + 顶部细线 + **无胶囊指示器**；
      // 选中 primary 蓝图标/文字，未选次文字色。
      navigationBarTheme: NavigationBarThemeData(
        backgroundColor: colorScheme.surface,
        surfaceTintColor: Colors.transparent,
        indicatorColor: Colors.transparent,
        height: 68,
        iconTheme: WidgetStateProperty.resolveWith(
          (states) => IconThemeData(
            size: 24,
            color: states.contains(WidgetState.selected)
                ? colorScheme.primary
                : (dark ? _textSecondaryDark : kColorTextSecondary),
          ),
        ),
        labelTextStyle: WidgetStateProperty.resolveWith(
          (states) => textTheme.labelMedium!.copyWith(
            color: states.contains(WidgetState.selected)
                ? colorScheme.primary
                : (dark ? _textSecondaryDark : kColorTextSecondary),
            fontWeight: FontWeight.w500,
          ),
        ),
      ),

      // 轻分隔线（不用粗边框）。
      dividerTheme: DividerThemeData(
        color: dark ? _dividerDark : _divider,
        thickness: 1,
        space: 1,
      ),
    );
  }

  static OutlineInputBorder _inputBorder(
    ColorScheme scheme,
    Color color, {
    double width = 1,
  }) => OutlineInputBorder(
    borderRadius: BorderRadius.circular(kRadiusField),
    borderSide: BorderSide(color: color, width: width),
  );

  /// 字阶（UI-03 §3）：24 页面标题 / 17 分组 / 16-14 正文 / 13-12 辅助。
  ///
  /// 只声明 fontSize/字重/颜色，字体族与缩放交给默认排版 + TextScaler
  /// （fontSize 随系统字体大小缩放）。
  static TextTheme _textTheme(ColorScheme scheme) {
    final onSurface = scheme.onSurface;
    final onSecondaryText = scheme.onSurfaceVariant;
    return TextTheme(
      titleLarge: TextStyle(
        fontSize: 24,
        fontWeight: FontWeight.w600,
        color: onSurface,
      ),
      titleMedium: TextStyle(
        fontSize: 17,
        fontWeight: FontWeight.w600,
        color: onSurface,
      ),
      titleSmall: TextStyle(
        fontSize: 16,
        fontWeight: FontWeight.w600,
        color: onSurface,
      ),
      bodyLarge: TextStyle(fontSize: 16, color: onSurface),
      bodyMedium: TextStyle(fontSize: 14, color: onSurface),
      bodySmall: TextStyle(fontSize: 13, color: onSecondaryText),
      labelLarge: TextStyle(
        fontSize: 14,
        fontWeight: FontWeight.w500,
        color: onSurface,
      ),
      labelMedium: TextStyle(
        fontSize: 12,
        fontWeight: FontWeight.w500,
        color: onSurface,
      ),
      labelSmall: TextStyle(
        fontSize: 12,
        fontWeight: FontWeight.w500,
        color: onSecondaryText,
      ),
    );
  }
}