/// 일정 컨트롤러 (MVCS의 Controller 레이어)
///
/// 비즈니스 로직과 상태 관리를 담당합니다.
/// View는 이 Controller를 통해 데이터에 접근합니다.
library;

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:intl/intl.dart';
import '../models/schedule.dart';
import '../services/schedules_service.dart';

/// 일정 상태
class ScheduleState {
  final DateTime selectedDate;
  final List<Schedule> schedules;
  final bool isLoading;
  final String? error;
  // 달력용 월별 일정 캐시 (key: "yyyy-MM")
  final Map<String, List<Schedule>> calendarCache;

  const ScheduleState({
    required this.selectedDate,
    this.schedules = const [],
    this.isLoading = false,
    this.error,
    this.calendarCache = const {},
  });

  /// 상태 복사 (불변성 유지)
  ScheduleState copyWith({
    DateTime? selectedDate,
    List<Schedule>? schedules,
    bool? isLoading,
    String? error,
    Map<String, List<Schedule>>? calendarCache,
  }) {
    return ScheduleState(
      selectedDate: selectedDate ?? this.selectedDate,
      schedules: schedules ?? this.schedules,
      isLoading: isLoading ?? this.isLoading,
      error: error,
      calendarCache: calendarCache ?? this.calendarCache,
    );
  }

  /// 선택된 날짜의 일정 목록
  List<Schedule> get selectedDateSchedules {
    final dateStr = DateFormat('yyyy-MM-dd').format(selectedDate);
    return schedules.where((s) => s.date.split('T')[0] == dateStr).toList();
  }

  /// 특정 날짜의 일정 (점 표시용, 최대 3개)
  /// 캐시에서 먼저 찾고, 없으면 현재 schedules에서 찾음
  List<Schedule> getDaySchedules(DateTime date) {
    final dateStr = DateFormat('yyyy-MM-dd').format(date);
    final cacheKey = DateFormat('yyyy-MM').format(date);

    // 캐시에 있으면 캐시에서 가져옴
    if (calendarCache.containsKey(cacheKey)) {
      return calendarCache[cacheKey]!
          .where((s) => s.date.split('T')[0] == dateStr)
          .take(3)
          .toList();
    }

    // 캐시에 없으면 현재 schedules에서 찾음
    return schedules.where((s) => s.date.split('T')[0] == dateStr).take(3).toList();
  }

  /// 특정 월의 일정이 캐시에 있는지 확인
  bool hasMonthCache(int year, int month) {
    final cacheKey = '$year-${month.toString().padLeft(2, '0')}';
    return calendarCache.containsKey(cacheKey);
  }

  /// 해당 달의 모든 날짜 배열
  List<DateTime> get daysInMonth {
    final year = selectedDate.year;
    final month = selectedDate.month;
    final lastDay = DateTime(year, month + 1, 0).day;
    return List.generate(lastDay, (i) => DateTime(year, month, i + 1));
  }
}

/// 일정 컨트롤러
class ScheduleController extends Notifier<ScheduleState> {
  @override
  ScheduleState build() {
    // 초기 상태
    final initialState = ScheduleState(selectedDate: DateTime.now());
    // 초기 데이터 로드
    Future.microtask(() => loadSchedules());
    return initialState;
  }

  /// 월별 일정 로드
  Future<void> loadSchedules() async {
    state = state.copyWith(isLoading: true, error: null);

    try {
      final schedules = await getSchedules(
        state.selectedDate.year,
        state.selectedDate.month,
      );
      // 현재 월 일정을 캐시에도 저장
      final cacheKey = '${state.selectedDate.year}-${state.selectedDate.month.toString().padLeft(2, '0')}';
      final newCache = Map<String, List<Schedule>>.from(state.calendarCache);
      newCache[cacheKey] = schedules;
      state = state.copyWith(
        schedules: schedules,
        isLoading: false,
        calendarCache: newCache,
      );
    } catch (e) {
      state = state.copyWith(isLoading: false, error: e.toString());
    }
  }

  /// 달력용 특정 월의 일정 비동기 로드 (UI 블로킹 없음)
  Future<void> loadCalendarMonth(int year, int month) async {
    final cacheKey = '$year-${month.toString().padLeft(2, '0')}';

    // 이미 캐시에 있으면 스킵
    if (state.calendarCache.containsKey(cacheKey)) return;

    try {
      final schedules = await getSchedules(year, month);
      // 비동기 완료 후 캐시 업데이트
      final newCache = Map<String, List<Schedule>>.from(state.calendarCache);
      newCache[cacheKey] = schedules;
      state = state.copyWith(calendarCache: newCache);
    } catch (e) {
      // 에러는 무시 (달력 점 표시가 안될 뿐)
    }
  }

  /// 날짜 선택
  void selectDate(DateTime date) {
    state = state.copyWith(selectedDate: date);
  }

  /// 월 변경
  void changeMonth(int delta) {
    final newDate = DateTime(
      state.selectedDate.year,
      state.selectedDate.month + delta,
      1,
    );
    final today = DateTime.now();

    // 이번 달이면 오늘 날짜, 다른 달이면 1일 선택
    final selectedDay = (newDate.year == today.year && newDate.month == today.month)
        ? today.day
        : 1;

    state = state.copyWith(
      selectedDate: DateTime(newDate.year, newDate.month, selectedDay),
    );
    loadSchedules();
  }

  /// 특정 날짜로 이동 (달력에서 선택 시)
  void goToDate(DateTime date) {
    final currentMonth = state.selectedDate.month;
    final currentYear = state.selectedDate.year;

    state = state.copyWith(selectedDate: date);

    // 월이 변경되면 일정 다시 로드
    if (date.month != currentMonth || date.year != currentYear) {
      loadSchedules();
    }
  }

  /// 오늘 여부
  bool isToday(DateTime date) {
    final today = DateTime.now();
    return date.year == today.year &&
        date.month == today.month &&
        date.day == today.day;
  }

  /// 선택된 날짜 여부
  bool isSelected(DateTime date) {
    return date.year == state.selectedDate.year &&
        date.month == state.selectedDate.month &&
        date.day == state.selectedDate.day;
  }
}

/// 일정 Provider
final scheduleProvider = NotifierProvider<ScheduleController, ScheduleState>(
  ScheduleController.new,
);

/// 검색 상태
class SearchState {
  final String searchTerm;
  final List<Schedule> results;
  final bool isLoading;
  final bool isFetchingMore;
  final bool hasMore;
  final int offset;
  final String? error;

  const SearchState({
    this.searchTerm = '',
    this.results = const [],
    this.isLoading = false,
    this.isFetchingMore = false,
    this.hasMore = true,
    this.offset = 0,
    this.error,
  });

  SearchState copyWith({
    String? searchTerm,
    List<Schedule>? results,
    bool? isLoading,
    bool? isFetchingMore,
    bool? hasMore,
    int? offset,
    String? error,
  }) {
    return SearchState(
      searchTerm: searchTerm ?? this.searchTerm,
      results: results ?? this.results,
      isLoading: isLoading ?? this.isLoading,
      isFetchingMore: isFetchingMore ?? this.isFetchingMore,
      hasMore: hasMore ?? this.hasMore,
      offset: offset ?? this.offset,
      error: error,
    );
  }
}

/// 검색 컨트롤러
class ScheduleSearchController extends Notifier<SearchState> {
  static const int _pageSize = 20;

  @override
  SearchState build() {
    return const SearchState();
  }

  /// 검색 실행
  Future<void> search(String query) async {
    if (query.trim().isEmpty) {
      state = const SearchState();
      return;
    }

    state = SearchState(searchTerm: query, isLoading: true);

    try {
      final result = await searchSchedules(query, offset: 0, limit: _pageSize);
      state = state.copyWith(
        results: result.schedules,
        isLoading: false,
        hasMore: result.hasMore,
        offset: result.schedules.length,
      );
    } catch (e) {
      state = state.copyWith(isLoading: false, error: e.toString());
    }
  }

  /// 다음 페이지 로드
  Future<void> loadMore() async {
    if (state.isFetchingMore || !state.hasMore || state.searchTerm.isEmpty) {
      return;
    }

    state = state.copyWith(isFetchingMore: true);

    try {
      final result = await searchSchedules(
        state.searchTerm,
        offset: state.offset,
        limit: _pageSize,
      );
      state = state.copyWith(
        results: [...state.results, ...result.schedules],
        isFetchingMore: false,
        hasMore: result.hasMore,
        offset: state.offset + result.schedules.length,
      );
    } catch (e) {
      state = state.copyWith(isFetchingMore: false, error: e.toString());
    }
  }

  /// 검색 초기화
  void clear() {
    state = const SearchState();
  }
}

/// 검색 Provider
final searchProvider = NotifierProvider<ScheduleSearchController, SearchState>(
  ScheduleSearchController.new,
);