import 'dart:async';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:intl/intl.dart';
import '../models/schedule_item.dart';
import '../services/schedule_service.dart';

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

  @override
  State<ScheduleListWidget> createState() => _ScheduleListWidgetState();
}

class _ScheduleListWidgetState extends State<ScheduleListWidget> {
  Timer? _timer;
  List<ScheduleItem> _schedules = [];
  bool _isLoading = true;
  String? _error;

  @override
  void initState() {
    super.initState();
    _fetchSchedules();
    _startAutoRefresh();
  }

  void _startAutoRefresh() {
    _timer = Timer.periodic(const Duration(seconds: 30), (timer) {
      _fetchSchedules();
    });
  }

  Future<void> _fetchSchedules() async {
    try {
      final data = await Provider.of<ScheduleService>(
        context,
        listen: false,
      ).fetchWeeklySchedules();

      if (mounted) {
        setState(() {
          _schedules = data;
          _isLoading = false;
          _error = null;
        });
      }
    } catch (e) {
      if (mounted) {
        setState(() {
          _error = 'Failed to load schedules';
          _isLoading = false;
        });
      }
    }
  }

  @override
  void dispose() {
    _timer?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: Theme.of(context).cardTheme.color,
        borderRadius: BorderRadius.circular(16),
      ),
      padding: const EdgeInsets.all(16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            '주간 일정',
            style: Theme.of(context).textTheme.titleLarge?.copyWith(
                  color: Colors.white,
                  fontWeight: FontWeight.bold,
                ),
          ),
          const SizedBox(height: 12),
          Expanded(
            child: _buildContent(),
          ),
        ],
      ),
    );
  }

  Widget _buildContent() {
    if (_isLoading && _schedules.isEmpty) {
      return const Center(child: CircularProgressIndicator());
    }

    if (_error != null && _schedules.isEmpty) {
      return Center(
        child: Text(
          _error!,
          style: const TextStyle(color: Colors.white54),
        ),
      );
    }

    // Correctly filter for current week (Sunday to Saturday)
    final now = DateTime.now();
    final today = DateTime(now.year, now.month, now.day);
    // In Dart, weekday is 1 (Mon) to 7 (Sun). 
    // To get Sunday: if Mon(1), subtract 1. if Sun(7), subtract 0.
    final daysToSubtract = now.weekday % 7;
    final startOfWeek = today.subtract(Duration(days: daysToSubtract));
    final endOfWeek = startOfWeek.add(const Duration(days: 6, hours: 23, minutes: 59, seconds: 59));

    final filteredSchedules = _schedules.where((item) {
      // Overlap check: schedule starts before week ends AND schedule ends after week starts
      return item.startDate.isBefore(endOfWeek) && item.endDate.isAfter(startOfWeek);
    }).toList();

    if (filteredSchedules.isEmpty) {
      return const Center(
        child: Text(
          '이번 주 일정이 없습니다',
          style: TextStyle(color: Colors.white54),
        ),
      );
    }

    // Sort by date
    final sortedSchedules = List<ScheduleItem>.from(filteredSchedules);
    sortedSchedules.sort((a, b) => a.startDate.compareTo(b.startDate));

    return ListView.separated(
      itemCount: sortedSchedules.length,
      separatorBuilder: (context, index) =>
          const Divider(color: Colors.white10),
      itemBuilder: (context, index) {
        final item = sortedSchedules[index];
        
        // Multi-day check
        final isMultiDay = item.startDate.year != item.endDate.year ||
            item.startDate.month != item.endDate.month ||
            item.startDate.day != item.endDate.day;

        String? dateRangeStr;
        if (isMultiDay) {
          final startStr = DateFormat('MM/dd').format(item.startDate);
          final endStr = DateFormat('MM/dd').format(item.endDate);
          dateRangeStr = '$startStr ~ $endStr';
        }

        return ListTile(
          contentPadding: EdgeInsets.zero,
          leading: Container(
            padding: const EdgeInsets.symmetric(
              horizontal: 10,
              vertical: 6,
            ),
            decoration: BoxDecoration(
              color: isMultiDay ? Colors.blue.withOpacity(0.2) : Colors.white10,
              borderRadius: BorderRadius.circular(8),
              border: isMultiDay ? Border.all(color: Colors.blue.withOpacity(0.5)) : null,
            ),
            child: FittedBox(
              fit: BoxFit.scaleDown,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                mainAxisSize: MainAxisSize.min,
                children: [
                  Text(
                    DateFormat('d').format(item.startDate),
                    style: TextStyle(
                      color: isMultiDay ? Colors.blue : Colors.white,
                      fontWeight: FontWeight.bold,
                      fontSize: 18,
                      height: 1.2,
                    ),
                  ),
                  Text(
                    DateFormat('E').format(item.startDate),
                    style: const TextStyle(
                      color: Colors.white70,
                      fontSize: 12,
                      height: 1.2,
                    ),
                  ),
                ],
              ),
            ),
          ),
          title: Text(
            item.title,
            style: const TextStyle(
              color: Colors.white,
              fontWeight: FontWeight.w500,
            ),
          ),
          subtitle: dateRangeStr != null
              ? Text(
                  dateRangeStr,
                  style: const TextStyle(
                    color: Colors.white,
                    fontWeight: FontWeight.bold,
                  ),
                )
              : null,
        );
      },
    );
  }
}