import 'package:get/get.dart';
import 'package:intl/intl.dart';
import 'package:flutter/material.dart';
import 'package:lunar/lunar.dart';

import '../../../data/models/assistant_directive.dart';
import '../../../data/services/assistant_directive_service.dart';
import '../views/widgets/calendar/calendar_event.dart';

/// 日历视图格式：月视图 / 周视图
enum _CalendarFormat { month, week }

/// 代办列表的统计范围：当天 / 本周 / 当月
enum CalendarScope {
  day('scopeDay'),
  week('scopeWeek'),
  month('scopeMonth');

  const CalendarScope(this.label);

  /// i18n key，展示处 `.tr`
  final String label;
}

/// 首页日历面板控制器（移植自 AI-study-machine 的 CalendarController）。
///
/// 几何/手势/折叠/翻页逻辑原样保留；数据层换成内存 mock（不接后端/不落库）。
class CalendarController extends GetxController
    with GetSingleTickerProviderStateMixin {
  // ==================== Rx 状态 ====================

  // 视图格式（月 / 周），默认周视图（折叠）
  final calendarFormat = _CalendarFormat.week.obs;

  // 焦点月份的 1 号（月 PageView 的页索引基准）
  // 不变量：focusedDay 总等于 DateTime(selectedDate.year, selectedDate.month, 1)
  final focusedDay = DateTime(DateTime.now().year, DateTime.now().month, 1).obs;

  // 当前选中日期
  final selectedDate = DateTime.now().obs;

  // 拖拽进度：0.0（月视图）→ 1.0（周视图）。默认 1.0：启动即为折叠的周视图
  final dragProgress = 1.0.obs;

  // 事件列表（mock）
  final RxList<CalendarEvent> events = <CalendarEvent>[].obs;

  /// 监听助手提醒变化的 worker，onClose 要停掉
  Worker? _reminderWorker;

  // 折叠态横向条的代办/花销筛选：null=全部，非空=只看该类别。
  // 点击"代办"/"花销"标签设置；点击日期（onDaySelected）重置为全部。
  final Rx<CalendarEventCategory?> categoryFilter =
      Rx<CalendarEventCategory?>(null);

  void setCategoryFilter(CalendarEventCategory category) {
    categoryFilter.value = category;
  }

  // ==================== 非响应式字段 ====================

  // PageView 基准日期（启动时锁定）
  late final DateTime _baseDay;
  DateTime get _baseMonth => DateTime(_baseDay.year, _baseDay.month, 1);
  DateTime get _baseWeek => _mondayOf(_baseDay);

  static const int _monthInitialPage = 1200; // 前后各 100 年
  static const int _weekInitialPage = 5200; // 前后各 100 年 × 52 周

  late final PageController monthPageController;
  late final PageController weekPageController;

  late final AnimationController _snapAnimation;

  // 拖拽累计状态
  double _dragStartProgress = 0;

  // snap 动画的 from/to/target
  double _pendingSnapFrom = 0;
  double _pendingSnapTo = 0;
  _CalendarFormat _pendingSnapTarget = _CalendarFormat.month;

  // 手势阈值
  static const double _flingVelocityThreshold = 500;

  // 动画时长上下限
  static const int _snapDurationMaxMs = 260;
  static const int _snapDurationMinMs = 120;

  // ==================== 生命周期 ====================

  @override
  void onInit() {
    super.onInit();
    _baseDay = DateTime.now();
    monthPageController = PageController(initialPage: _monthInitialPage);
    weekPageController = PageController(initialPage: _weekInitialPage);
    _snapAnimation = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: _snapDurationMaxMs),
    )..addListener(_onSnapAnimationTick);
    // 加载内存 mock 数据（不接后端/不落库）
    _rebuildEvents();
    // EMAI 助手定的闹钟落地后要立刻出现在这里，不用退出重进
    if (Get.isRegistered<AssistantDirectiveService>()) {
      _reminderWorker = ever<List<AssistantReminder>>(
        AssistantDirectiveService.to.reminders,
        (_) => _rebuildEvents(),
      );
    }
  }

  /// mock 演示数据 + EMAI 助手落下来的提醒
  void _rebuildEvents() {
    final list = <CalendarEvent>[...mockCalendarEvents()];
    if (Get.isRegistered<AssistantDirectiveService>()) {
      for (final r in AssistantDirectiveService.to.reminders) {
        list.addAll(_expandReminder(r));
      }
    }
    events.assignAll(list);
  }

  /// 把一条提醒摊成日历事件。
  ///
  /// 重复提醒在协议里只有一条记录（`repeat=每天` / `周一`），日历要按天展示，
  /// 所以在可见窗口内逐日摊开。窗口取「今天前 7 天 ~ 后 60 天」：往前留几天是
  /// 为了让用户还能看到刚过去的提醒，往后 60 天覆盖月视图翻两页。
  List<CalendarEvent> _expandReminder(AssistantReminder r) {
    final title = r.content.isNotEmpty ? r.content : 'alarm'.tr;
    final start = TimeOfDay(hour: r.hour, minute: r.minute);

    CalendarEvent make(DateTime day, String suffix) => CalendarEvent(
          id: '${r.id}$suffix',
          title: title,
          // 重复规则原文放描述里，用户能看懂"每周一"比看懂 weekly 容易
          description: r.repeatRaw,
          date: DateTime(day.year, day.month, day.day),
          startTime: start,
          location: '—',
          tag: 'demoTagReminder'.tr,
          color: const Color(0xFF22C1A6),
          taskStatus: r.done ? 2 : 0,
        );

    // 一次性：只在指定那天（没给 date 就算今天）
    if (r.repeat == RepeatRule.once || r.repeat == RepeatRule.unknown) {
      final day = r.date != null ? DateTime.tryParse(r.date!) : null;
      return [make(day ?? DateTime.now(), '')];
    }

    final today = DateTime.now();
    final from = DateTime(today.year, today.month, today.day)
        .subtract(const Duration(days: 7));
    final out = <CalendarEvent>[];
    for (var i = 0; i < 67; i++) {
      final day = from.add(Duration(days: i));
      final hit = switch (r.repeat) {
        RepeatRule.daily => true,
        RepeatRule.weekly => day.weekday == r.weekday,
        RepeatRule.weekdays => day.weekday <= DateTime.friday,
        RepeatRule.weekend =>
          day.weekday == DateTime.saturday || day.weekday == DateTime.sunday,
        _ => false,
      };
      if (hit) out.add(make(day, '@${day.year}${day.month}${day.day}'));
    }
    return out;
  }

  @override
  void onClose() {
    _reminderWorker?.dispose();
    _snapAnimation.dispose();
    monthPageController.dispose();
    weekPageController.dispose();
    super.onClose();
  }

  // ==================== 拖拽 ====================

  /// 垂直拖拽开始
  void onDragStart() {
    if (_snapAnimation.isAnimating) _snapAnimation.stop();
    _dragStartProgress = dragProgress.value;
    // 若当前是周视图即将扩展：预先把 monthPageController 同步到 focusedDay 所在月
    if (calendarFormat.value == _CalendarFormat.week &&
        monthPageController.hasClients) {
      monthPageController.jumpToPage(monthPageIndexFromDate(focusedDay.value));
    }
  }

  /// 垂直拖拽过程中：按位移连续更新 dragProgress
  /// [dy] 帧增量 Y；[dragSpan] 月视图高度 - 周视图高度（总拖拽距离）
  void onDragUpdate(double dy, double dragSpan) {
    // dy 正 = 往下拖 = progress 减小（朝月视图）
    // dy 负 = 往上拖 = progress 增大（朝周视图）
    final delta = -dy / dragSpan;
    dragProgress.value = (_dragStartProgress + delta).clamp(0.0, 1.0);
    _dragStartProgress = dragProgress.value;
  }

  /// 垂直拖拽结束：按速度或位置决定 snap 方向
  void onDragEnd(double velocityY) {
    final current = dragProgress.value;
    _CalendarFormat target;
    if (velocityY.abs() > _flingVelocityThreshold) {
      target = velocityY < 0 ? _CalendarFormat.week : _CalendarFormat.month;
    } else {
      target = current >= 0.5 ? _CalendarFormat.week : _CalendarFormat.month;
    }
    _snapToFormat(target);
  }

  // ==================== Snap 动画 ====================

  void _snapToFormat(_CalendarFormat target) {
    final targetProgress = target == _CalendarFormat.week ? 1.0 : 0.0;
    final from = dragProgress.value;

    _pendingSnapFrom = from;
    _pendingSnapTo = targetProgress;
    _pendingSnapTarget = target;

    final distance = (targetProgress - from).abs();
    final ms = (_snapDurationMaxMs * distance).round().clamp(
          _snapDurationMinMs,
          _snapDurationMaxMs,
        );

    _snapAnimation
      ..reset()
      ..duration = Duration(milliseconds: ms)
      ..forward();
  }

  void _onSnapAnimationTick() {
    final curved = Curves.easeOutCubic.transform(_snapAnimation.value);
    dragProgress.value = _lerp(_pendingSnapFrom, _pendingSnapTo, curved);

    if (_snapAnimation.isCompleted) {
      if (calendarFormat.value != _pendingSnapTarget) {
        calendarFormat.value = _pendingSnapTarget;
        _syncOtherPageController();
      }
    }
  }

  void _syncOtherPageController() {
    if (calendarFormat.value == _CalendarFormat.week) {
      if (weekPageController.hasClients) {
        weekPageController
            .jumpToPage(weekPageIndexFromDate(selectedDate.value));
      }
    } else {
      if (monthPageController.hasClients) {
        monthPageController
            .jumpToPage(monthPageIndexFromDate(focusedDay.value));
      }
    }
  }

  double _lerp(double a, double b, double t) => a + (b - a) * t;

  // ==================== PageView 翻页回调 ====================

  void onMonthPageChanged(int pageIndex) {
    final newMonth = monthFromPageIndex(pageIndex);
    focusedDay.value = newMonth;
    selectedDate.value = newMonth; // 维护不变量：回到新月 1 号
  }

  void onWeekPageChanged(int pageIndex) {
    final newMonday = weekMondayFromPageIndex(pageIndex);
    // 保持用户选中的是周几
    final oldSel = selectedDate.value;
    final dayOffsetInWeek = (oldSel.weekday - 1).clamp(0, 6);
    final newSelected = newMonday.add(Duration(days: dayOffsetInWeek));
    selectedDate.value = newSelected;
    focusedDay.value = DateTime(newSelected.year, newSelected.month, 1);
  }

  // ==================== 日期选择 ====================

  /// 用户点击某日（月视图或周视图）：切换日期后重置代办/花销筛选，显示全部
  void onDaySelected(DateTime day) {
    selectedDate.value = day;
    focusedDay.value = DateTime(day.year, day.month, 1);
    categoryFilter.value = null;
  }

  /// 回到今天（替代参考里的"今天"FAB）
  void jumpToToday() {
    final today = DateTime.now();
    final targetMonth = DateTime(today.year, today.month, 1);
    if (isWeekView) {
      if (weekPageController.hasClients) {
        weekPageController.jumpToPage(weekPageIndexFromDate(today));
      }
    } else {
      if (monthPageController.hasClients) {
        monthPageController.jumpToPage(monthPageIndexFromDate(targetMonth));
      }
    }
    // jumpToPage 会触发 onPageChanged 把 selectedDate 置为首日，故下一帧纠正为今天
    WidgetsBinding.instance.addPostFrameCallback((_) {
      selectedDate.value = today;
      focusedDay.value = targetMonth;
    });
  }

  // ==================== 查询/派生 ====================

  List<CalendarEvent> get eventsForSelectedDate => events
      .where((event) => DateUtils.isSameDay(event.date, selectedDate.value))
      .toList();

  /// 选中日期的代办事项（代办表）
  List<CalendarEvent> get todosForSelectedDate => eventsForSelectedDate
      .where((event) => event.category == CalendarEventCategory.todo)
      .toList();

  /// 选中日期的花销记录（花销表）
  List<CalendarEvent> get expensesForSelectedDate => eventsForSelectedDate
      .where((event) => event.category == CalendarEventCategory.expense)
      .toList();

  /// 折叠态横向条实际展示的条目：按 [categoryFilter] 筛选，null 时代办+花销都显示
  List<CalendarEvent> get visibleEventsForSelectedDate {
    switch (categoryFilter.value) {
      case CalendarEventCategory.todo:
        return todosForSelectedDate;
      case CalendarEventCategory.expense:
        return expensesForSelectedDate;
      case null:
        return eventsForSelectedDate;
    }
  }

  /// 选中日期的花销合计（元）
  double get totalExpenseForSelectedDate => expensesForSelectedDate
      .fold(0, (sum, event) => sum + (event.amount ?? 0));

  String get selectedDateLabel =>
      '${selectedDate.value.month}月${selectedDate.value.day}日';

  // ==================== 日/周/月范围 ====================

  /// 代办列表当前的统计范围，默认「日」
  final scope = CalendarScope.day.obs;

  void setScope(CalendarScope value) => scope.value = value;

  /// 当前范围的起止日期（含首尾，都归一到 0 点）
  ({DateTime start, DateTime end}) get scopeRange {
    final sel = DateTime(
        selectedDate.value.year, selectedDate.value.month, selectedDate.value.day);
    switch (scope.value) {
      case CalendarScope.day:
        return (start: sel, end: sel);
      case CalendarScope.week:
        final monday = _mondayOf(sel);
        return (start: monday, end: monday.add(const Duration(days: 6)));
      case CalendarScope.month:
        final first = DateTime(sel.year, sel.month, 1);
        // 下个月 0 号 = 本月最后一天，自动处理大小月和闰年
        final last = DateTime(sel.year, sel.month + 1, 0);
        return (start: first, end: last);
    }
  }

  /// 范围标题，如「8月17日」「8月11日 - 8月17日」「2026年8月」
  String get scopeLabel {
    final r = scopeRange;
    // 日期格式跟随当前语言：中文「8月17日」，英文「Aug 17」，西语「17 ago」
    final String tag = (Get.locale ?? const Locale('zh', 'CN')).toLanguageTag();
    final md = DateFormat.MMMd(tag);
    final ym = DateFormat.yMMMM(tag);
    switch (scope.value) {
      case CalendarScope.day:
        return md.format(r.start);
      case CalendarScope.week:
        return '${md.format(r.start)} - ${md.format(r.end)}';
      case CalendarScope.month:
        return ym.format(r.start);
    }
  }

  bool _inScope(DateTime d) {
    final r = scopeRange;
    final day = DateTime(d.year, d.month, d.day);
    return !day.isBefore(r.start) && !day.isAfter(r.end);
  }

  /// 当前范围内的全部事件，按日期升序（同一天内保持原顺序）
  List<CalendarEvent> get eventsForScope {
    final list = events.where((e) => _inScope(e.date)).toList();
    list.sort((a, b) => a.date.compareTo(b.date));
    return list;
  }

  List<CalendarEvent> get todosForScope => eventsForScope
      .where((e) => e.category == CalendarEventCategory.todo)
      .toList();

  List<CalendarEvent> get expensesForScope => eventsForScope
      .where((e) => e.category == CalendarEventCategory.expense)
      .toList();

  double get totalExpenseForScope =>
      expensesForScope.fold(0, (sum, e) => sum + (e.amount ?? 0));

  /// 按天分组（周/月视图下列表要按日期分节展示）。
  /// key 是归一到 0 点的日期，已按时间升序。
  List<({DateTime day, List<CalendarEvent> events})> get eventsGroupedByDay {
    final map = <DateTime, List<CalendarEvent>>{};
    for (final e in eventsForScope) {
      final key = DateTime(e.date.year, e.date.month, e.date.day);
      map.putIfAbsent(key, () => <CalendarEvent>[]).add(e);
    }
    final keys = map.keys.toList()..sort();
    return keys
        .map((k) => (day: k, events: map[k]!))
        .toList(growable: false);
  }

  bool hasEventOn(DateTime day) =>
      events.any((event) => DateUtils.isSameDay(event.date, day));

  /// 当前是否为周视图
  bool get isWeekView => calendarFormat.value == _CalendarFormat.week;

  // ==================== 工具方法 ====================

  /// 某天所在周的周一
  DateTime _mondayOf(DateTime d) {
    return DateTime(d.year, d.month, d.day)
        .subtract(Duration(days: d.weekday - 1));
  }

  /// 月 PageView 页索引 → 该月 1 号
  DateTime monthFromPageIndex(int pageIndex) {
    final diff = pageIndex - _monthInitialPage;
    return DateTime(_baseMonth.year, _baseMonth.month + diff, 1);
  }

  /// 日期 → 月 PageView 页索引
  int monthPageIndexFromDate(DateTime date) {
    return _monthInitialPage +
        (date.year - _baseMonth.year) * 12 +
        (date.month - _baseMonth.month);
  }

  /// 周 PageView 页索引 → 该周的周一
  DateTime weekMondayFromPageIndex(int pageIndex) {
    final diff = pageIndex - _weekInitialPage;
    return _baseWeek.add(Duration(days: diff * 7));
  }

  /// 日期 → 周 PageView 页索引（基于该日期所在周的周一）
  int weekPageIndexFromDate(DateTime date) {
    final targetMonday = _mondayOf(date);
    final diffDays = targetMonday.difference(_baseWeek).inDays;
    return _weekInitialPage + diffDays ~/ 7;
  }

  /// 月视图下选中日期所在 6-行布局的 Y 偏移（像素）
  double selectedRowYOffset(double rowHeightWithSpacing) {
    final sel = selectedDate.value;
    final firstDay = DateTime(sel.year, sel.month, 1);
    final startOffset = (firstDay.weekday + 6) % 7; // 周一=0..周日=6
    final dayInGrid = sel.day + startOffset - 1; // 0..41
    final rowIndex = dayInGrid ~/ 7;
    return rowIndex * rowHeightWithSpacing;
  }

  /// 给 View 用：指定月份的 42 天列表（含前后月占位）
  List<DateTime> daysForMonth(DateTime month) {
    final firstDay = DateTime(month.year, month.month, 1);
    final startOffset = (firstDay.weekday + 6) % 7;
    final startDate = firstDay.subtract(Duration(days: startOffset));
    return List.generate(
      42,
      (index) =>
          DateTime(startDate.year, startDate.month, startDate.day + index),
    );
  }

  // ==================== 农历/节日 ====================

  /// 获取某日期的农历或节日文本（优先显示节日）
  /// 当前语言是不是中文。农历、节气、干支这些只有中文语境下才有意义，
  /// 切到英语/西语时直接不显示，比硬塞一串中文好。
  static bool get isChineseLocale =>
      (Get.locale?.languageCode ?? 'zh').toLowerCase().startsWith('zh');

  String getLunarOrFestival(DateTime date) {
    if (!isChineseLocale) return '';
    try {
      final lunar = Lunar.fromDate(date);

      final solarFestival = _getSolarFestival(date.month, date.day);
      if (solarFestival != null) return solarFestival;

      final lunarFestival = _getLunarFestival(lunar.getMonth(), lunar.getDay());
      if (lunarFestival != null) return lunarFestival;

      final jieQi = lunar.getJieQi();
      if (jieQi.isNotEmpty) return jieQi;

      return _formatLunarDay(lunar);
    } catch (e) {
      return '';
    }
  }

  String _formatLunarDay(Lunar lunar) {
    final day = lunar.getDay();
    if (day == 1) {
      return '${lunar.getMonthInChinese()}月';
    }
    return lunar.getDayInChinese();
  }

  String? _getSolarFestival(int month, int day) {
    final key = '$month-$day';
    const festivals = {
      '1-1': '元旦',
      '2-14': '情人节',
      '3-8': '妇女节',
      '3-12': '植树节',
      '4-1': '愚人节',
      '5-1': '劳动节',
      '5-4': '青年节',
      '6-1': '儿童节',
      '7-1': '建党节',
      '8-1': '建军节',
      '9-10': '教师节',
      '10-1': '国庆节',
      '12-24': '平安夜',
      '12-25': '圣诞节',
    };
    return festivals[key];
  }

  String? _getLunarFestival(int month, int day) {
    final key = '$month-$day';
    const festivals = {
      '1-1': '春节',
      '1-15': '元宵节',
      '2-2': '龙抬头',
      '5-5': '端午节',
      '7-7': '七夕节',
      '7-15': '中元节',
      '8-15': '中秋节',
      '9-9': '重阳节',
      '12-8': '腊八节',
      '12-23': '小年',
    };
    return festivals[key];
  }
}