import 'dart:io';
import 'package:flutter/material.dart';
import 'package:receive_sharing_intent/receive_sharing_intent.dart';

/// 图片网格预览组件 - 用于批量模式下显示多张图片的网格布局
/// 支持图片预览、选择状态和错误处理
class ImageGridPreview extends StatelessWidget {
  /// 分享的图片文件列表
  final List<SharedMediaFile> images;

  /// 选中的图片索引列表
  final List<int> selectedIndices;

  /// 图片选择状态变更回调
  final Function(int index, bool selected) onSelectionChanged;

  /// 是否显示选择框
  final bool showSelection;

  /// 网格列数
  final int crossAxisCount;

  /// 图片间距
  final double spacing;

  /// 边距
  final EdgeInsets padding;

  const ImageGridPreview({
    Key? key,
    required this.images,
    required this.selectedIndices,
    required this.onSelectionChanged,
    this.showSelection = true,
    this.crossAxisCount = 2,
    this.spacing = 8.0,
    this.padding = const EdgeInsets.all(16),
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    if (images.isEmpty) {
      return _buildEmptyState(context);
    }

    return Padding(
      padding: padding,
      child: GridView.builder(
        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
          crossAxisCount: crossAxisCount,
          crossAxisSpacing: spacing,
          mainAxisSpacing: spacing,
          childAspectRatio: 1.0,
        ),
        itemCount: images.length,
        itemBuilder: (context, index) => _buildImageItem(context, index),
      ),
    );
  }

  /// 构建空状态
  Widget _buildEmptyState(BuildContext context) {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(
            Icons.photo_library_outlined,
            size: 64,
            color: Theme.of(context).colorScheme.outline,
          ),
          const SizedBox(height: 16),
          Text(
            '暂无图片',
            style: Theme.of(context).textTheme.bodyLarge?.copyWith(
              color: Theme.of(context).colorScheme.outline,
            ),
          ),
        ],
      ),
    );
  }

  /// 构建单个图片项
  Widget _buildImageItem(BuildContext context, int index) {
    final imageFile = images[index];
    final isSelected = selectedIndices.contains(index);

    return GestureDetector(
      onTap: () {
        if (showSelection) {
          onSelectionChanged(index, !isSelected);
        } else {
          _showImagePreview(context, index);
        }
      },
      onLongPress: () => _showImagePreview(context, index),
      child: Container(
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(8),
          border: isSelected
              ? Border.all(
                  color: Theme.of(context).colorScheme.primary,
                  width: 3,
                )
              : null,
          boxShadow: [
            BoxShadow(
              color: Colors.black.withOpacity(0.1),
              blurRadius: 4,
              offset: const Offset(0, 2),
            ),
          ],
        ),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(5), // 稍小以避免边框溢出
          child: Stack(
            fit: StackFit.expand,
            children: [
              // 图片显示
              Image.file(
                File(imageFile.path),
                fit: BoxFit.cover,
                errorBuilder: (context, error, stackTrace) =>
                    _buildErrorPlaceholder(context),
                frameBuilder: (context, child, frame, wasSynchronouslyLoaded) {
                  if (frame == null) return _buildLoadingPlaceholder(context);
                  return child;
                },
              ),

              // 选择标记
              if (showSelection)
                Positioned(
                  top: 8,
                  right: 8,
                  child: Container(
                    width: 24,
                    height: 24,
                    decoration: BoxDecoration(
                      color: isSelected
                          ? Theme.of(context).colorScheme.primary
                          : Colors.white.withOpacity(0.7),
                      shape: BoxShape.circle,
                      border: Border.all(
                        color: isSelected
                            ? Theme.of(context).colorScheme.primary
                            : Colors.grey.withOpacity(0.5),
                        width: 2,
                      ),
                    ),
                    child: isSelected
                        ? const Icon(
                            Icons.check,
                            color: Colors.white,
                            size: 16,
                          )
                        : null,
                  ),
                ),

              // 文件类型标记
              if (_isGifImage(imageFile.path))
                Positioned(
                  bottom: 8,
                  left: 8,
                  child: Container(
                    padding: const EdgeInsets.symmetric(
                      horizontal: 6,
                      vertical: 2,
                    ),
                    decoration: BoxDecoration(
                      color: Colors.black.withOpacity(0.6),
                      borderRadius: BorderRadius.circular(4),
                    ),
                    child: const Text(
                      'GIF',
                      style: TextStyle(
                        color: Colors.white,
                        fontSize: 10,
                        fontWeight: FontWeight.bold,
                      ),
                    ),
                  ),
                ),
            ],
          ),
        ),
      ),
    );
  }

  /// 构建加载中的占位符
  Widget _buildLoadingPlaceholder(BuildContext context) {
    return Container(
      color: Colors.grey[200],
      child: Center(
        child: CircularProgressIndicator(
          strokeWidth: 2,
          valueColor: AlwaysStoppedAnimation<Color>(
            Theme.of(context).colorScheme.primary,
          ),
        ),
      ),
    );
  }

  /// 构建错误占位符
  Widget _buildErrorPlaceholder(BuildContext context) {
    return Container(
      color: Colors.grey[200],
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(
            Icons.broken_image,
            size: 32,
            color: Colors.grey[400],
          ),
          const SizedBox(height: 4),
          Text(
            '加载失败',
            style: TextStyle(
              color: Colors.grey[600],
              fontSize: 12,
            ),
          ),
        ],
      ),
    );
  }

  /// 显示图片预览
  void _showImagePreview(BuildContext context, int index) {
    Navigator.of(context).push(
      PageRouteBuilder<void>(
        pageBuilder: (context, animation, secondaryAnimation) =>
            ImagePreviewPage(
          images: images,
          initialIndex: index,
        ),
        transitionsBuilder: (context, animation, secondaryAnimation, child) {
          return FadeTransition(
            opacity: animation,
            child: child,
          );
        },
      ),
    );
  }

  /// 检查是否为GIF图片
  bool _isGifImage(String path) {
    return path.toLowerCase().endsWith('.gif');
  }
}

/// 图片预览页面 - 全屏显示单张图片
class ImagePreviewPage extends StatefulWidget {
  /// 图片文件列表
  final List<SharedMediaFile> images;

  /// 初始显示的图片索引
  final int initialIndex;

  const ImagePreviewPage({
    Key? key,
    required this.images,
    required this.initialIndex,
  }) : super(key: key);

  @override
  State<ImagePreviewPage> createState() => _ImagePreviewPageState();
}

class _ImagePreviewPageState extends State<ImagePreviewPage>
    with SingleTickerProviderStateMixin {
  late PageController _pageController;
  late AnimationController _animationController;
  late Animation<double> _fadeAnimation;

  /// 当前显示的图片索引
  int currentIndex = 0;

  @override
  void initState() {
    super.initState();
    currentIndex = widget.initialIndex;
    _pageController = PageController(initialPage: currentIndex);

    // 动画控制器
    _animationController = AnimationController(
      duration: const Duration(milliseconds: 300),
      vsync: this,
    );
    _fadeAnimation = Tween<double>(
      begin: 0.0,
      end: 1.0,
    ).animate(CurvedAnimation(
      parent: _animationController,
      curve: Curves.easeInOut,
    ));

    // 延迟显示UI控件
    Future.delayed(const Duration(milliseconds: 500), () {
      if (mounted) {
        _animationController.forward();
      }
    });
  }

  @override
  void dispose() {
    _pageController.dispose();
    _animationController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: Stack(
        children: [
          // 图片显示区域
          PageView.builder(
            controller: _pageController,
            itemCount: widget.images.length,
            onPageChanged: (index) {
              setState(() {
                currentIndex = index;
              });
            },
            itemBuilder: (context, index) => _buildFullImage(context, index),
          ),

          // 顶部工具栏
          FadeTransition(
            opacity: _fadeAnimation,
            child: _buildTopToolbar(),
          ),

          // 底部指示器
          FadeTransition(
            opacity: _fadeAnimation,
            child: _buildBottomIndicator(),
          ),
        ],
      ),
    );
  }

  /// 构建全屏图片
  Widget _buildFullImage(BuildContext context, int index) {
    final imageFile = widget.images[index];

    return InteractiveViewer(
      panEnabled: true,
      boundaryMargin: const EdgeInsets.all(20),
      minScale: 0.5,
      maxScale: 4.0,
      child: Image.file(
        File(imageFile.path),
        fit: BoxFit.contain,
        errorBuilder: (context, error, stackTrace) => _buildErrorView(),
      ),
    );
  }

  /// 构建错误视图
  Widget _buildErrorView() {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          const Icon(
            Icons.broken_image,
            size: 64,
            color: Colors.white54,
          ),
          const SizedBox(height: 16),
          Text(
            '图片加载失败',
            style: TextStyle(
              color: Colors.white54,
              fontSize: 16,
            ),
          ),
        ],
      ),
    );
  }

  /// 构建顶部工具栏
  Widget _buildTopToolbar() {
    return Positioned(
      top: 0,
      left: 0,
      right: 0,
      child: Container(
        height: MediaQuery.of(context).padding.top + 56,
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: Alignment.topCenter,
            end: Alignment.bottomCenter,
            colors: [
              Colors.black.withOpacity(0.7),
              Colors.transparent,
            ],
          ),
        ),
        padding: EdgeInsets.only(
          top: MediaQuery.of(context).padding.top,
          left: 16,
          right: 16,
        ),
        child: Row(
          children: [
            // 返回按钮
            IconButton(
              onPressed: () => Navigator.of(context).pop(),
              icon: const Icon(
                Icons.arrow_back,
                color: Colors.white,
              ),
            ),

            const Spacer(),

            // 图片信息
            if (_isGifImage(widget.images[currentIndex].path))
              Container(
                padding: const EdgeInsets.symmetric(
                  horizontal: 8,
                  vertical: 4,
                ),
                decoration: BoxDecoration(
                  color: Colors.white.withOpacity(0.2),
                  borderRadius: BorderRadius.circular(12),
                ),
                child: const Text(
                  'GIF',
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 12,
                    fontWeight: FontWeight.bold,
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }

  /// 构建底部指示器
  Widget _buildBottomIndicator() {
    return Positioned(
      bottom: MediaQuery.of(context).padding.bottom + 16,
      left: 0,
      right: 0,
      child: Center(
        child: Container(
          padding: const EdgeInsets.symmetric(
            horizontal: 12,
            vertical: 6,
          ),
          decoration: BoxDecoration(
            color: Colors.black.withOpacity(0.5),
            borderRadius: BorderRadius.circular(16),
          ),
          child: Text(
            '${currentIndex + 1} / ${widget.images.length}',
            style: const TextStyle(
              color: Colors.white,
              fontSize: 14,
            ),
          ),
        ),
      ),
    );
  }

  /// 检查是否为GIF图片
  bool _isGifImage(String path) {
    return path.toLowerCase().endsWith('.gif');
  }
}