import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:fl_chart/fl_chart.dart';
import 'package:intl/intl.dart';
import '../providers/expense_provider.dart';
import '../models/transaction_model.dart';

class StatsScreen extends StatefulWidget {
  const StatsScreen({super.key});

  @override
  State<StatsScreen> createState() => _StatsScreenState();
}

class _StatsScreenState extends State<StatsScreen> with SingleTickerProviderStateMixin {
  late TabController _tabController;
  DateTime _selectedMonth = DateTime.now();

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 3, vsync: this);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('数据统计'),
        bottom: TabBar(
          controller: _tabController,
          tabs: const [
            Tab(text: '概览'),
            Tab(text: '趋势'),
            Tab(text: '对比'),
          ],
        ),
        actions: [
          IconButton(
            icon: const Icon(Icons.calendar_month),
            onPressed: _pickMonth,
          ),
        ],
      ),
      body: Consumer<ExpenseProvider>(
        builder: (context, provider, child) {
          final transactions = provider.transactions.where((t) {
            return t.date.year == _selectedMonth.year && t.date.month == _selectedMonth.month;
          }).toList();

          if (transactions.isEmpty) {
             return Center(child: Text('${DateFormat('yyyy年MM月').format(_selectedMonth)} 无数据'));
          }

          return TabBarView(
            controller: _tabController,
            children: [
              _buildPieChart(provider, transactions),
              _buildLineChart(provider, transactions),
              _buildBarChart(provider, transactions),
            ],
          );
        },
      ),
    );
  }

  Future<void> _pickMonth() async {
    final picked = await showDatePicker(
      context: context,
      initialDate: _selectedMonth,
      firstDate: DateTime(2020),
      lastDate: DateTime(2030),
      helpText: '选择月份',
    );
    if (picked != null) {
      setState(() {
        _selectedMonth = picked;
      });
    }
  }

  Widget _buildPieChart(ExpenseProvider provider, List<TransactionModel> transactions) {
    final expenseTransactions = transactions.where((t) => t.type == 'expense').toList();
    if (expenseTransactions.isEmpty) return const Center(child: Text('无支出数据'));

    final categoryTotals = <int, double>{};
    for (var t in expenseTransactions) {
      categoryTotals[t.categoryId] = (categoryTotals[t.categoryId] ?? 0) + t.amount;
    }

    final totalExpense = expenseTransactions.fold(0.0, (sum, t) => sum + t.amount);

    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Column(
        children: [
          Text('总支出: ¥${totalExpense.toStringAsFixed(2)}', style: const TextStyle(fontSize: 20, fontWeight: FontWeight.bold)),
          const SizedBox(height: 32),
          SizedBox(
            height: 250,
            child: PieChart(
              PieChartData(
                sections: categoryTotals.entries.map((entry) {
                  final category = provider.getCategoryById(entry.key);
                  final percentage = (entry.value / totalExpense) * 100;
                  
                  return PieChartSectionData(
                    color: Color(category.color),
                    value: entry.value,
                    title: '${percentage.toStringAsFixed(1)}%',
                    radius: 50,
                    titleStyle: const TextStyle(
                      fontSize: 12,
                      fontWeight: FontWeight.bold,
                      color: Colors.white,
                    ),
                  );
                }).toList(),
                sectionsSpace: 2,
                centerSpaceRadius: 40,
              ),
            ),
          ),
          const SizedBox(height: 20),
          Expanded(
            child: ListView.builder(
              itemCount: categoryTotals.length,
              itemBuilder: (context, index) {
                final categoryId = categoryTotals.keys.elementAt(index);
                final amount = categoryTotals[categoryId]!;
                final category = provider.getCategoryById(categoryId);
                
                return ListTile(
                  leading: CircleAvatar(
                    backgroundColor: Color(category.color),
                    child: Icon(_getIconData(category.icon), color: Colors.white),
                  ),
                  title: Text(category.name),
                  trailing: Text('¥${amount.toStringAsFixed(2)}'),
                );
              },
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildLineChart(ExpenseProvider provider, List<TransactionModel> transactions) {
    // Daily Expense Trend
    final dailyTotals = <int, double>{};
    final daysInMonth = DateUtils.getDaysInMonth(_selectedMonth.year, _selectedMonth.month);
    
    // Initialize all days to 0
    for (int i = 1; i <= daysInMonth; i++) {
      dailyTotals[i] = 0.0;
    }

    for (var t in transactions.where((t) => t.type == 'expense')) {
      dailyTotals[t.date.day] = (dailyTotals[t.date.day] ?? 0) + t.amount;
    }

    final spots = dailyTotals.entries
      .map((e) => FlSpot(e.key.toDouble(), e.value))
      .toList()
      ..sort((a, b) => a.x.compareTo(b.x));

    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Column(
        children: [
          const Text('每日支出趋势', style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
          const SizedBox(height: 32),
          Expanded(
            child: LineChart(
              LineChartData(
                gridData: const FlGridData(show: false),
                titlesData: FlTitlesData(
                  bottomTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      interval: 5,
                      getTitlesWidget: (value, meta) {
                        return Text('${value.toInt()}日', style: const TextStyle(fontSize: 10));
                      },
                    ),
                  ),
                  leftTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                  topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                  rightTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                ),
                borderData: FlBorderData(show: true, border: Border.all(color: Colors.grey.withValues(alpha: 0.2))),
                lineBarsData: [
                  LineChartBarData(
                    spots: spots,
                    isCurved: true,
                    color: Colors.blue,
                    barWidth: 3,
                    dotData: const FlDotData(show: false),
                    belowBarData: BarAreaData(show: true, color: Colors.blue.withValues(alpha: 0.1)),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildBarChart(ExpenseProvider provider, List<TransactionModel> transactions) {
    final income = transactions.where((t) => t.type == 'income').fold(0.0, (sum, t) => sum + t.amount);
    final expense = transactions.where((t) => t.type == 'expense').fold(0.0, (sum, t) => sum + t.amount);

    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: Column(
        children: [
          const Text('收支对比', style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
          const SizedBox(height: 32),
          Expanded(
            child: BarChart(
              BarChartData(
                alignment: BarChartAlignment.spaceAround,
                maxY: (income > expense ? income : expense) * 1.2,
                barTouchData: BarTouchData(enabled: false),
                titlesData: FlTitlesData(
                  bottomTitles: AxisTitles(
                    sideTitles: SideTitles(
                      showTitles: true,
                      getTitlesWidget: (value, meta) {
                        switch (value.toInt()) {
                          case 0: return const Text('收入', style: TextStyle(color: Colors.green));
                          case 1: return const Text('支出', style: TextStyle(color: Colors.red));
                          default: return const Text('');
                        }
                      },
                    ),
                  ),
                  leftTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                  topTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                  rightTitles: const AxisTitles(sideTitles: SideTitles(showTitles: false)),
                ),
                gridData: const FlGridData(show: false),
                borderData: FlBorderData(show: false),
                barGroups: [
                  BarChartGroupData(
                    x: 0,
                    barRods: [BarChartRodData(toY: income, color: Colors.green, width: 20)],
                  ),
                  BarChartGroupData(
                    x: 1,
                    barRods: [BarChartRodData(toY: expense, color: Colors.red, width: 20)],
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

  IconData _getIconData(String iconName) {
    switch (iconName) {
      case 'restaurant': return Icons.restaurant;
      case 'directions_bus': return Icons.directions_bus;
      case 'shopping_cart': return Icons.shopping_cart;
      case 'movie': return Icons.movie;
      case 'local_hospital': return Icons.local_hospital;
      case 'attach_money': return Icons.attach_money;
      case 'trending_up': return Icons.trending_up;
      case 'breakfast_dining': return Icons.breakfast_dining;
      case 'lunch_dining': return Icons.lunch_dining;
      case 'dinner_dining': return Icons.dinner_dining;
      case 'subway': return Icons.subway;
      case 'local_taxi': return Icons.local_taxi;
      default: return Icons.category;
    }
  }
}