import 'package:flutter/material.dart';
import "package:flutter_staggered_grid_view/flutter_staggered_grid_view.dart";
import '../models/activity.dart';
import '../services/activity_service.dart';
import '../utils/constants.dart';
import 'activity_detail_screen.dart';
import 'create_activity_screen.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});
  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  String _selectedCategory = '全部';
  String _timeFilter = '全部';
  List<Activity> _activities = [];
  bool _loading = true;

  @override
  void initState() {
    super.initState();
    _loadActivities();
  }

  void _loadActivities() {
    setState(() {
      _activities = ActivityService.getMockActivities();
      _loading = false;
    });
  }

  List<Activity> get _filteredActivities {
    return _activities.where((a) {
      if (_selectedCategory != '全部' && a.category != _selectedCategory) return false;
      if (_timeFilter == '今天') {
        return DateUtils.isSameDay(a.time, DateTime.now());
      }
      if (_timeFilter == '明天') {
        final tomorrow = DateTime.now().add(const Duration(days: 1));
        return DateUtils.isSameDay(a.time, tomorrow);
      }
      return true;
    }).toList();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.location_on, size: 18, color: Color(0xFF1976D2)),
            const SizedBox(width: 4),
            const Text('成都', style: TextStyle(fontSize: 16, color: Color(0xFF666666))),
            const SizedBox(width: 16),
            Expanded(
              child: Container(
                height: 36,
                decoration: BoxDecoration(
                  color: const Color(0xFFF5F5F5),
                  borderRadius: BorderRadius.circular(18),
                ),
                child: const Row(
                  children: [
                    SizedBox(width: 12),
                    Icon(Icons.search, size: 20, color: Color(0xFF999999)),
                    SizedBox(width: 8),
                    Text('搜索活动', style: TextStyle(fontSize: 14, color: Color(0xFF999999))),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
      body: _loading
          ? const Center(child: CircularProgressIndicator())
          : RefreshIndicator(
              onRefresh: () async => _loadActivities(),
              child: CustomScrollView(
                slivers: [
                  // Category chips
                  SliverToBoxAdapter(
                    child: SizedBox(
                      height: 48,
                      child: ListView(
                        scrollDirection: Axis.horizontal,
                        padding: const EdgeInsets.symmetric(horizontal: 16),
                        children: AppConstants.activityCategories.map((cat) {
                          final selected = _selectedCategory == cat;
                          return Padding(
                            padding: const EdgeInsets.only(right: 8),
                            child: ChoiceChip(
                              label: Text(cat, style: TextStyle(fontSize: 14, color: selected ? Colors.white : const Color(0xFF666666))),
                              selected: selected,
                              selectedColor: const Color(0xFF1976D2),
                              backgroundColor: const Color(0xFFF5F5F5),
                              onSelected: (_) => setState(() => _selectedCategory = cat),
                            ),
                          );
                        }).toList(),
                      ),
                    ),
                  ),
                  // Time filter
                  SliverToBoxAdapter(
                    child: Padding(
                      padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
                      child: Row(
                        children: ['全部', '今天', '明天', '本周'].map((t) {
                          final selected = _timeFilter == t;
                          return Padding(
                            padding: const EdgeInsets.only(right: 12),
                            child: GestureDetector(
                              onTap: () => setState(() => _timeFilter = t),
                              child: Text(t, style: TextStyle(
                                fontSize: 16,
                                color: selected ? const Color(0xFF1976D2) : const Color(0xFF999999),
                                fontWeight: selected ? FontWeight.w600 : FontWeight.normal,
                              )),
                            ),
                          );
                        }).toList(),
                      ),
                    ),
                  ),
                  // Activity list
                  SliverToBoxAdapter(
                    child: MasonryGridView.count(
                      crossAxisCount: 2,
                      mainAxisSpacing: 10,
                      crossAxisSpacing: 10,
                      padding: const EdgeInsets.all(12),
                      shrinkWrap: true,
                      physics: const NeverScrollableScrollPhysics(),
                      itemCount: _filteredActivities.length,
                      itemBuilder: (ctx, index) {
                        final activity = _filteredActivities[index];
                        return _ActivityCard(
                          key: ValueKey(activity.id),
                          activity: activity,
                          imageHeight: index.isOdd ? 160.0 : 210.0,
                          onTap: () => Navigator.push(
                            context,
                            MaterialPageRoute(
                              builder: (_) => ActivityDetailScreen(activity: activity),
                            ),
                          ),
                        );
                      },
                    ),
                  ),
                  const SliverToBoxAdapter(child: SizedBox(height: 80)),
                ],
              ),
            ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: () => Navigator.push(context, MaterialPageRoute(builder: (_) => const CreateActivityScreen())),
        icon: const Icon(Icons.add),
        label: const Text('发起活动', style: TextStyle(fontSize: 16)),
        backgroundColor: const Color(0xFF1976D2),
        foregroundColor: Colors.white,
      ),
    );
  }
}

class _ActivityCard extends StatefulWidget {
  final Activity activity;
  final double imageHeight;
  final VoidCallback onTap;
  const _ActivityCard({
    super.key,
    required this.activity,
    required this.imageHeight,
    required this.onTap,
  });

  @override
  State<_ActivityCard> createState() => _ActivityCardState();
}

class _ActivityCardState extends State<_ActivityCard> {
  @override
  Widget build(BuildContext context) {
    final activity = widget.activity;
    return Material(
      color: Colors.transparent,
      child: InkWell(
        onTap: widget.onTap,
        borderRadius: BorderRadius.circular(12),
        child: Container(
          decoration: BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.circular(12),
            boxShadow: [
              BoxShadow(
                color: Colors.black.withOpacity(0.06),
                blurRadius: 6,
                offset: const Offset(0, 2),
              ),
            ],
          ),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              ClipRRect(
                borderRadius: const BorderRadius.only(
                  topLeft: Radius.circular(12),
                  topRight: Radius.circular(12),
                ),
                child: Image.network(
                  "https://picsum.photos/seed/${activity.title.hashCode.abs()}/400/300",
                  height: widget.imageHeight,
                  width: double.infinity,
                  fit: BoxFit.cover,
                  errorBuilder: (_, __, ___) => Container(
                    height: widget.imageHeight,
                    color: const Color(0xFFE0E0E0),
                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.all(8),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      activity.title,
                      maxLines: 2,
                      overflow: TextOverflow.ellipsis,
                      style: const TextStyle(
                        fontSize: 14,
                        fontWeight: FontWeight.w700,
                        color: Color(0xFF333333),
                      ),
                    ),
                    const SizedBox(height: 4),
                    Row(
                      children: [
                        CircleAvatar(
                          radius: 10,
                          backgroundImage: NetworkImage(
                            "https://i.pravatar.cc/40?img=${activity.category.hashCode.abs() % 40 + 1}",
                          ),
                        ),
                        const SizedBox(width: 4),
                        Text(
                          activity.category,
                          style: const TextStyle(
                            fontSize: 12,
                            color: Color(0xFF999999),
                          ),
                        ),
                        const Spacer(),
                        Text(
                          "${activity.currentParticipants}人",
                          style: const TextStyle(
                            fontSize: 12,
                            color: Color(0xFFFF6B35),
                          ),
                        ),
                      ],
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}