import 'package:flutter/material.dart';

/// 空状态组件库 - 提供多种样式的空状态页面展示
/// 包括无数据、无结果、错误等不同场景的空状态显示

/// 基础空状态组件 - 通用的空状态显示组件
/// [icon] 空状态图标，使用Material Icons
/// [title] 空状态标题文本
/// [message] 空状态描述文本
/// [actionText] 操作按钮文本，null时不显示按钮
/// [onAction] 操作按钮点击回调，null时按钮不可点击
/// [iconSize] 图标大小，null时使用默认大小
/// [iconColor] 图标颜色，null时使用主题色彩
class EmptyState extends StatelessWidget {
  /// 空状态图标，使用Material Icons
  final IconData icon;

  /// 空状态标题文本
  final String title;

  /// 空状态描述文本
  final String? message;

  /// 操作按钮文本，null时不显示按钮
  final String? actionText;

  /// 操作按钮点击回调，null时按钮不可点击
  final VoidCallback? onAction;

  /// 图标大小，null时使用默认大小
  final double? iconSize;

  /// 图标颜色，null时使用主题色彩
  final Color? iconColor;

  /// 自定义图标组件，优先级高于icon参数
  final Widget? customIcon;

  /// 自定义操作组件，优先级高于actionText参数
  final Widget? customAction;

  /// 主要内容垂直间距
  final double spacing;

  /// 主要内容内边距
  final EdgeInsetsGeometry? padding;

  /// 是否显示边框装饰
  final bool showBorder;

  /// 边框圆角半径
  final double borderRadius;

  /// 背景颜色，null时使用透明背景
  final Color? backgroundColor;

  const EmptyState({
    super.key,
    required this.icon,
    required this.title,
    this.message,
    this.actionText,
    this.onAction,
    this.iconSize,
    this.iconColor,
    this.customIcon,
    this.customAction,
    this.spacing = 16,
    this.padding,
    this.showBorder = false,
    this.borderRadius = 12,
    this.backgroundColor,
  });

  /// 创建无数据空状态 - 用于列表、网格等无数据场景
  factory EmptyState.noData({
    String? title,
    String? message,
    String? actionText,
    VoidCallback? onAction,
    IconData? icon,
  }) {
    return EmptyState(
      icon: icon ?? Icons.inbox_outlined,
      title: title ?? '暂无数据',
      message: message ?? '当前没有可显示的数据',
      actionText: actionText,
      onAction: onAction,
      iconColor: Colors.grey,
    );
  }

  /// 创建无搜索结果空状态 - 用于搜索无结果场景
  factory EmptyState.noSearchResults({
    String? searchQuery,
    VoidCallback? onClearSearch,
  }) {
    return EmptyState(
      icon: Icons.search_off_outlined,
      title: '未找到相关结果',
      message: searchQuery != null
          ? '未找到与"$searchQuery"相关的内容'
          : '未找到相关内容，请尝试其他关键词',
      actionText: onClearSearch != null ? '清除搜索' : null,
      onAction: onClearSearch,
      iconColor: Colors.grey,
    );
  }

  /// 创建网络错误空状态 - 用于网络连接失败场景
  factory EmptyState.networkError({
    VoidCallback? onRetry,
  }) {
    return EmptyState(
      icon: Icons.wifi_off_outlined,
      title: '网络连接失败',
      message: '请检查网络连接后重试',
      actionText: '重新加载',
      onAction: onRetry,
      iconColor: Colors.orange,
    );
  }

  /// 创建服务器错误空状态 - 用于服务器异常场景
  factory EmptyState.serverError({
    VoidCallback? onRetry,
  }) {
    return EmptyState(
      icon: Icons.cloud_off_outlined,
      title: '服务器异常',
      message: '服务器暂时无法访问，请稍后重试',
      actionText: '重新加载',
      onAction: onRetry,
      iconColor: Colors.red,
    );
  }

  /// 创建权限不足空状态 - 用于无权限访问场景
  factory EmptyState.permissionDenied({
    VoidCallback? onRequestPermission,
  }) {
    return EmptyState(
      icon: Icons.lock_outline,
      title: '权限不足',
      message: '您没有访问此内容的权限',
      actionText: onRequestPermission != null ? '申请权限' : null,
      onAction: onRequestPermission,
      iconColor: Colors.orange,
    );
  }

  /// 创建收藏为空状态 - 用于收藏列表为空场景
  factory EmptyState.emptyFavorites({
    VoidCallback? onBrowse,
  }) {
    return EmptyState(
      icon: Icons.favorite_border_outlined,
      title: '暂无收藏',
      message: '您还没有收藏任何内容',
      actionText: onBrowse != null ? '去浏览' : null,
      onAction: onBrowse,
      iconColor: Colors.pink,
    );
  }

  /// 创建购物车为空状态 - 用于购物车为空场景
  factory EmptyState.emptyCart({
    VoidCallback? onShop,
  }) {
    return EmptyState(
      icon: Icons.shopping_cart_outlined,
      title: '购物车是空的',
      message: '您还没有添加任何商品',
      actionText: onShop != null ? '去购物' : null,
      onAction: onShop,
      iconColor: Colors.blue,
    );
  }

  /// 创建历史记录为空状态 - 用于历史记录为空场景
  factory EmptyState.emptyHistory({
    VoidCallback? onBrowse,
  }) {
    return EmptyState(
      icon: Icons.history_outlined,
      title: '暂无历史记录',
      message: '您还没有任何操作记录',
      actionText: onBrowse != null ? '去浏览' : null,
      onAction: onBrowse,
      iconColor: Colors.grey,
    );
  }

  /// 创建文件为空状态 - 用于文件列表为空场景
  factory EmptyState.emptyFiles({
    VoidCallback? onUpload,
  }) {
    return EmptyState(
      icon: Icons.folder_open_outlined,
      title: '文件夹是空的',
      message: '此文件夹中还没有任何文件',
      actionText: onUpload != null ? '上传文件' : null,
      onAction: onUpload,
      iconColor: Colors.blue,
    );
  }

  /// 创建图片为空状态 - 用于图片列表为空场景
  factory EmptyState.emptyImages({
    VoidCallback? onAddImages,
  }) {
    return EmptyState(
      icon: Icons.photo_library_outlined,
      title: '暂无图片',
      message: '您还没有添加任何图片',
      actionText: onAddImages != null ? '添加图片' : null,
      onAction: onAddImages,
      iconColor: Colors.purple,
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    Widget content = Column(
      mainAxisSize: MainAxisSize.min,
      mainAxisAlignment: MainAxisAlignment.center,
      crossAxisAlignment: CrossAxisAlignment.center,
      children: [
        // 图标部分
        if (customIcon != null) ...[
          customIcon!,
          SizedBox(height: spacing),
        ] else ...[
          Icon(
            icon,
            size: iconSize ?? 64,
            color: iconColor ?? theme.colorScheme.onSurface.withOpacity(0.4),
          ),
          SizedBox(height: spacing),
        ],

        // 标题部分
        Text(
          title,
          style: theme.textTheme.titleLarge?.copyWith(
            fontWeight: FontWeight.w600,
            color: theme.colorScheme.onSurface.withOpacity(0.8),
          ),
          textAlign: TextAlign.center,
        ),

        // 描述文本部分
        if (message != null) ...[
          SizedBox(height: spacing * 0.5),
          Text(
            message!,
            style: theme.textTheme.bodyMedium?.copyWith(
              color: theme.colorScheme.onSurface.withOpacity(0.6),
            ),
            textAlign: TextAlign.center,
          ),
        ],

        // 操作按钮部分
        if (customAction != null) ...[
          SizedBox(height: spacing * 1.5),
          customAction!,
        ] else if (actionText != null) ...[
          SizedBox(height: spacing * 1.5),
          ElevatedButton.icon(
            onPressed: onAction,
            icon: const Icon(Icons.refresh, size: 18),
            label: Text(actionText!),
            style: ElevatedButton.styleFrom(
              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
              shape: RoundedRectangleBorder(
                borderRadius: BorderRadius.circular(8),
              ),
            ),
          ),
        ],
      ],
    );

    // 添加内边距
    content = Padding(
      padding: padding ?? const EdgeInsets.all(24),
      child: content,
    );

    // 添加边框装饰
    if (showBorder) {
      content = Container(
        decoration: BoxDecoration(
          color: backgroundColor ?? theme.colorScheme.surface.withOpacity(0.5),
          border: Border.all(
            color: theme.colorScheme.outline.withOpacity(0.2),
            width: 1,
          ),
          borderRadius: BorderRadius.circular(borderRadius),
        ),
        child: content,
      );
    } else if (backgroundColor != null) {
      content = Container(
        decoration: BoxDecoration(
          color: backgroundColor,
          borderRadius: BorderRadius.circular(borderRadius),
        ),
        child: content,
      );
    }

    return content;
  }
}

/// 空状态页面 - 全屏空状态显示，包含图标、文本和操作按钮
/// [icon] 空状态图标
/// [title] 空状态标题
/// [message] 空状态描述文本
/// [actionText] 操作按钮文本
/// [onAction] 操作按钮点击回调
/// [showAppBar] 是否显示应用栏
/// [appBarTitle] 应用栏标题
class EmptyStatePage extends StatelessWidget {
  /// 空状态图标
  final IconData icon;

  /// 空状态标题
  final String title;

  /// 空状态描述文本
  final String? message;

  /// 操作按钮文本
  final String? actionText;

  /// 操作按钮点击回调
  final VoidCallback? onAction;

  /// 是否显示应用栏
  final bool showAppBar;

  /// 应用栏标题
  final String? appBarTitle;

  /// 自定义空状态组件，优先级高于其他参数
  final Widget? customEmptyState;

  /// 背景颜色，null时使用主题背景色
  final Color? backgroundColor;

  const EmptyStatePage({
    super.key,
    required this.icon,
    required this.title,
    this.message,
    this.actionText,
    this.onAction,
    this.showAppBar = false,
    this.appBarTitle,
    this.customEmptyState,
    this.backgroundColor,
  });

  /// 创建无数据空状态页面
  factory EmptyStatePage.noData({
    String? title,
    String? message,
    String? actionText,
    VoidCallback? onAction,
    bool showAppBar = false,
    String? appBarTitle,
  }) {
    return EmptyStatePage(
      icon: Icons.inbox_outlined,
      title: title ?? '暂无数据',
      message: message ?? '当前没有可显示的数据',
      actionText: actionText,
      onAction: onAction,
      showAppBar: showAppBar,
      appBarTitle: appBarTitle ?? '无数据',
    );
  }

  /// 创建无搜索结果空状态页面
  factory EmptyStatePage.noSearchResults({
    String? searchQuery,
    VoidCallback? onClearSearch,
    bool showAppBar = false,
  }) {
    return EmptyStatePage(
      icon: Icons.search_off_outlined,
      title: '未找到相关结果',
      message: searchQuery != null
          ? '未找到与"$searchQuery"相关的内容'
          : '未找到相关内容，请尝试其他关键词',
      actionText: onClearSearch != null ? '清除搜索' : null,
      onAction: onClearSearch,
      showAppBar: showAppBar,
      appBarTitle: '搜索结果',
    );
  }

  /// 创建网络错误空状态页面
  factory EmptyStatePage.networkError({
    VoidCallback? onRetry,
    bool showAppBar = false,
  }) {
    return EmptyStatePage(
      icon: Icons.wifi_off_outlined,
      title: '网络连接失败',
      message: '请检查网络连接后重试',
      actionText: '重新加载',
      onAction: onRetry,
      showAppBar: showAppBar,
      appBarTitle: '网络错误',
    );
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Scaffold(
      backgroundColor: backgroundColor ?? theme.colorScheme.background,
      appBar: showAppBar
          ? AppBar(
              title: Text(appBarTitle ?? title),
              centerTitle: true,
            )
          : null,
      body: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(24),
          child: customEmptyState ?? EmptyState(
            icon: icon,
            title: title,
            message: message,
            actionText: actionText,
            onAction: onAction,
            showBorder: false,
          ),
        ),
      ),
    );
  }
}

/// 空状态构建器 - 根据条件显示空状态或正常内容
/// [isEmpty] 是否为空状态
/// [emptyState] 空状态组件
/// [child] 正常内容组件
class EmptyStateBuilder extends StatelessWidget {
  /// 是否为空状态
  final bool isEmpty;

  /// 空状态组件
  final Widget emptyState;

  /// 正常内容组件
  final Widget child;

  const EmptyStateBuilder({
    super.key,
    required this.isEmpty,
    required this.emptyState,
    required this.child,
  });

  @override
  Widget build(BuildContext context) {
    if (isEmpty) {
      return emptyState;
    }
    return child;
  }
}

/// 空状态包装器 - 简化版本，自动构建空状态
/// [isEmpty] 是否为空状态
/// [icon] 空状态图标
/// [title] 空状态标题
/// [message] 空状态描述
/// [actionText] 操作按钮文本
/// [onAction] 操作按钮点击回调
/// [child] 正常内容组件
class EmptyStateWrapper extends StatelessWidget {
  /// 是否为空状态
  final bool isEmpty;

  /// 空状态图标
  final IconData icon;

  /// 空状态标题
  final String title;

  /// 空状态描述
  final String? message;

  /// 操作按钮文本
  final String? actionText;

  /// 操作按钮点击回调
  final VoidCallback? onAction;

  /// 正常内容组件
  final Widget child;

  /// 自定义空状态组件，优先级高于其他参数
  final Widget? customEmptyState;

  const EmptyStateWrapper({
    super.key,
    required this.isEmpty,
    required this.icon,
    required this.title,
    required this.child,
    this.message,
    this.actionText,
    this.onAction,
    this.customEmptyState,
  });

  @override
  Widget build(BuildContext context) {
    if (isEmpty) {
      return customEmptyState ?? EmptyState(
        icon: icon,
        title: title,
        message: message,
        actionText: actionText,
        onAction: onAction,
      );
    }
    return child;
  }
}