import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:lucide_icons/lucide_icons.dart';
import '../../../../core/router/app_routes.dart';
import '../../../home/ui/navigation/home_return_policy.dart';

import '../../../../core/di/injection.dart';
import '../../../../core/theme/design_tokens.dart';
import '../../../../shared/widgets/app_pressable.dart';
import '../../data/models/schedule_item_model.dart';
import '../../data/services/calendar_repository.dart';
import '../calendar_state_manager.dart';
import '../calendar_time_utils.dart';
import '../utils/event_color_resolver.dart';
import '../dayweek/day_event_layout_engine.dart';
import '../dayweek/day_timeline_metrics.dart';
import '../dayweek/day_view_scale.dart';
import '../widgets/bottom_dock.dart';

class CalendarDayWeekScreen extends StatefulWidget {
  final DateTime? initialDate;
  final bool resetToToday;

  const CalendarDayWeekScreen({
    super.key,
    this.initialDate,
    this.resetToToday = false,
  });

  @override
  State<CalendarDayWeekScreen> createState() => _CalendarDayWeekScreenState();
}

class _CalendarDayWeekScreenState extends State<CalendarDayWeekScreen>
    with WidgetsBindingObserver {
  static const double _dayItemWidth = 44;
  static const double _dayItemGap = 12;
  static const double _minEventTapHeight = 32;
  static const List<String> _dayNames = ['日', '一', '二', '三', '四', '五', '六'];

  final DayEventLayoutEngine _layoutEngine = const DayEventLayoutEngine();
  final Map<int, Offset> _activePointers = {};
  final ScrollController _dayStripController = ScrollController();

  DayViewScale _scale = DayViewScale.defaultScale();
  DayViewScale _pinchStartScale = DayViewScale.defaultScale();
  double? _pinchStartDistance;

  late final CalendarStateManager _calendarManager;
  late DateTime _selectedDate;
  late List<DateTime> _monthDates;
  List<ScheduleItemModel> _events = const [];

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _calendarManager = sl<CalendarStateManager>();

    if (widget.resetToToday) {
      _calendarManager.resetToToday();
    }

    _selectedDate = widget.initialDate ?? _calendarManager.selectedDate;
    _updateMonthDates();
    _loadEvents();

    WidgetsBinding.instance.addPostFrameCallback((_) {
      _scrollToSelectedDate();
    });
  }

  void _updateMonthDates() {
    _monthDates = monthDatesFor(_selectedDate);
  }

  Future<void> _loadEvents({bool forceRefresh = false}) async {
    final events = await sl<CalendarRepository>().getDayEvents(
      _selectedDate,
      forceRefresh: forceRefresh,
    );
    if (!mounted) {
      return;
    }
    setState(() {
      _events = events;
    });
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    _dayStripController.dispose();
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.resumed) {
      _loadEvents(forceRefresh: true);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.todoBg,
      body: PopScope(
        canPop: false,
        onPopInvokedWithResult: (didPop, result) {
          if (!didPop) {
            returnToHomePreserveState(context, forceGoHome: true);
          }
        },
        child: SafeArea(
          child: Stack(
            children: [
              Positioned.fill(
                top: 154,
                bottom: 84,
                child: Listener(
                  onPointerDown: _handlePointerDown,
                  onPointerMove: _handlePointerMove,
                  onPointerUp: _handlePointerUp,
                  onPointerCancel: _handlePointerCancel,
                  behavior: HitTestBehavior.translucent,
                  child: SingleChildScrollView(
                    child: Padding(
                      padding: const EdgeInsets.only(
                        left: AppSpacing.lg,
                        right: AppSpacing.lg,
                        top: 2,
                      ),
                      child: RepaintBoundary(child: _buildTimelineBoard()),
                    ),
                  ),
                ),
              ),
              Positioned(top: 0, left: 0, right: 0, child: _buildHeader()),
              Positioned(top: 68, left: 0, right: 0, child: _buildWeekStrip()),
              Positioned(
                bottom: 0,
                left: 0,
                right: 0,
                child: _buildBottomDock(),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void _goToToday() {
    final today = DateTime.now();
    setState(() {
      _selectedDate = today;
      _scale = DayViewScale.defaultScale();
    });
    _calendarManager.setSelectedDate(today);
    _updateMonthDates();
    _scrollToSelectedDate(animate: true);
    _loadEvents();
  }

  void _handlePointerDown(PointerDownEvent event) {
    _activePointers[event.pointer] = event.position;
    if (_activePointers.length == 2) {
      final pointers = _activePointers.values.toList(growable: false);
      _pinchStartDistance = (pointers[0] - pointers[1]).distance;
      _pinchStartScale = _scale;
    }
  }

  void _handlePointerMove(PointerMoveEvent event) {
    if (!_activePointers.containsKey(event.pointer)) {
      return;
    }
    _activePointers[event.pointer] = event.position;
    if (_activePointers.length != 2 || _pinchStartDistance == null) {
      return;
    }

    final pointers = _activePointers.values.toList(growable: false);
    final currentDistance = (pointers[0] - pointers[1]).distance;
    final startDistance = _pinchStartDistance!;
    if (startDistance <= 0) {
      return;
    }

    final nextScale = _pinchStartScale.zoomByFactor(
      currentDistance / startDistance,
    );
    if ((nextScale.hourHeight - _scale.hourHeight).abs() < 0.1) {
      return;
    }
    setState(() {
      _scale = nextScale;
    });
  }

  void _handlePointerUp(PointerUpEvent event) {
    _handlePointerRemove(event.pointer);
  }

  void _handlePointerCancel(PointerCancelEvent event) {
    _handlePointerRemove(event.pointer);
  }

  void _handlePointerRemove(int pointer) {
    _activePointers.remove(pointer);
    if (_activePointers.length < 2) {
      _pinchStartDistance = null;
    }
  }

  Widget _buildHeader() {
    final monthLabel = '${_selectedDate.year}年${_selectedDate.month}月';
    final isNotToday = !isSameDay(_selectedDate, DateTime.now());

    return SizedBox(
      height: 68,
      child: Padding(
        padding: const EdgeInsets.only(left: 20, right: 20, top: 12, bottom: 8),
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.center,
          children: [
            AppPressable(
              borderRadius: BorderRadius.circular(AppRadius.xl),
              onTap: () => context.go('/calendar/month'),
              child: Container(
                height: 36,
                padding: const EdgeInsets.symmetric(horizontal: 10),
                decoration: BoxDecoration(
                  color: AppColors.messageBtnWrap,
                  borderRadius: BorderRadius.circular(AppRadius.xl),
                  border: Border.all(color: AppColors.messageBtnBorder),
                ),
                child: Row(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    const Icon(
                      LucideIcons.chevronLeft,
                      size: 16,
                      color: AppColors.slate700,
                    ),
                    const SizedBox(width: 6),
                    AnimatedSwitcher(
                      duration: const Duration(milliseconds: 160),
                      switchInCurve: Curves.easeOut,
                      switchOutCurve: Curves.easeOut,
                      transitionBuilder: (child, animation) {
                        return FadeTransition(
                          opacity: animation,
                          child: SlideTransition(
                            position: Tween<Offset>(
                              begin: const Offset(0, 0.12),
                              end: Offset.zero,
                            ).animate(animation),
                            child: child,
                          ),
                        );
                      },
                      child: Text(
                        monthLabel,
                        key: ValueKey(monthLabel),
                        style: const TextStyle(
                          fontSize: 14,
                          fontWeight: FontWeight.w600,
                          color: AppColors.slate700,
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ),
            const Spacer(),
            if (isNotToday)
              AppPressable(
                borderRadius: BorderRadius.circular(AppRadius.xl),
                onTap: _goToToday,
                child: Container(
                  height: 36,
                  padding: const EdgeInsets.symmetric(horizontal: 12),
                  decoration: BoxDecoration(
                    color: AppColors.messageBtnWrap,
                    borderRadius: BorderRadius.circular(AppRadius.xl),
                    border: Border.all(color: AppColors.messageBtnBorder),
                  ),
                  child: const Center(
                    child: Text(
                      '今天',
                      style: TextStyle(
                        fontSize: 14,
                        fontWeight: FontWeight.w600,
                        color: AppColors.slate700,
                      ),
                    ),
                  ),
                ),
              ),
            if (isNotToday) const SizedBox(width: 8),
            AppPressable(
              borderRadius: BorderRadius.circular(AppRadius.full),
              onTap: () => context.push(
                '${AppRoutes.calendarEventCreate}?date=${formatYmd(_selectedDate)}',
              ),
              child: Container(
                width: 36,
                height: 36,
                decoration: BoxDecoration(
                  color: AppColors.blue600,
                  borderRadius: BorderRadius.circular(AppRadius.full),
                ),
                child: const Icon(
                  LucideIcons.plus,
                  size: 20,
                  color: AppColors.white,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildWeekStrip() {
    final stripKey = ValueKey('${_selectedDate.year}-${_selectedDate.month}');

    return SizedBox(
      height: 86,
      child: AnimatedSwitcher(
        duration: const Duration(milliseconds: 180),
        switchInCurve: Curves.easeOut,
        switchOutCurve: Curves.easeOut,
        child: ListView.separated(
          key: stripKey,
          controller: _dayStripController,
          physics: const BouncingScrollPhysics(),
          scrollDirection: Axis.horizontal,
          itemCount: _monthDates.length,
          separatorBuilder: (context, index) =>
              const SizedBox(width: _dayItemGap),
          itemBuilder: (context, index) {
            final date = _monthDates[index];
            final isSelected = isSameDay(date, _selectedDate);
            final isWeekend = date.weekday % 7 == 0 || date.weekday % 7 == 6;

            return AppPressable(
              borderRadius: BorderRadius.circular(AppRadius.xl),
              onTap: () {
                setState(() {
                  _selectedDate = date;
                });
                _calendarManager.setSelectedDate(date);
                _updateMonthDates();
                _scrollToSelectedDate(animate: true);
                _loadEvents();
              },
              child: SizedBox(
                width: _dayItemWidth,
                child: _buildDayItem(date, isSelected, isWeekend),
              ),
            );
          },
        ),
      ),
    );
  }

  void _scrollToSelectedDate({bool animate = false}) {
    if (!_dayStripController.hasClients) {
      return;
    }
    final index = _monthDates.indexWhere(
      (date) => isSameDay(date, _selectedDate),
    );
    if (index < 0) {
      return;
    }

    final targetCenter =
        index * (_dayItemWidth + _dayItemGap) + (_dayItemWidth / 2);
    final viewport = _dayStripController.position.viewportDimension;
    var offset = targetCenter - (viewport / 2);
    final max = _dayStripController.position.maxScrollExtent;
    if (offset < 0) {
      offset = 0;
    }
    if (offset > max) {
      offset = max;
    }

    if (animate) {
      _dayStripController.animateTo(
        offset,
        duration: const Duration(milliseconds: 180),
        curve: Curves.easeOut,
      );
      return;
    }
    _dayStripController.jumpTo(offset);
  }

  Widget _buildDayItem(DateTime date, bool isSelected, bool isWeekend) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.center,
      mainAxisSize: MainAxisSize.min,
      children: [
        Text(
          _dayNames[date.weekday % 7],
          style: TextStyle(
            fontSize: 11,
            color: isWeekend ? AppColors.slate400 : AppColors.slate600,
          ),
        ),
        const SizedBox(height: 2),
        AnimatedContainer(
          duration: const Duration(milliseconds: 140),
          curve: Curves.easeOut,
          width: 32,
          height: 32,
          decoration: BoxDecoration(
            color: isSelected ? AppColors.blue100 : Colors.transparent,
            borderRadius: BorderRadius.circular(AppRadius.full),
          ),
          child: Center(
            child: Text(
              '${date.day}',
              style: TextStyle(
                fontSize: 17,
                fontWeight: isSelected ? FontWeight.w700 : FontWeight.w600,
                color: isSelected
                    ? AppColors.blue600
                    : (isWeekend ? AppColors.slate400 : AppColors.slate900),
              ),
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildTimelineBoard() {
    final now = DateTime.now();
    final showCurrent = shouldShowCurrentMarker(_selectedDate, now);

    return LayoutBuilder(
      builder: (context, constraints) {
        final boardWidth = constraints.maxWidth;
        final boardHeight = DayTimelineMetrics.timelineHeight(_scale);
        final eventAreaLeft = DayTimelineMetrics.eventAreaLeft();
        final eventAreaWidth = DayTimelineMetrics.eventAreaWidth(boardWidth);

        final layouts = _layoutEngine.layout(
          events: _events,
          scale: _scale,
          eventAreaLeft: eventAreaLeft,
          eventAreaWidth: eventAreaWidth,
        );

        return SizedBox(
          height: boardHeight,
          child: Stack(
            children: [
              RepaintBoundary(
                child: _buildTimelineGrid(
                  boardHeight: boardHeight,
                  eventAreaLeft: eventAreaLeft,
                ),
              ),
              if (showCurrent)
                _buildCurrentTimeMarker(now: now, boardHeight: boardHeight),
              RepaintBoundary(
                child: Stack(
                  clipBehavior: Clip.none,
                  children: [
                    for (final layout in layouts)
                      _buildEventCard(layout: layout, boardHeight: boardHeight),
                  ],
                ),
              ),
            ],
          ),
        );
      },
    );
  }

  Widget _buildTimelineGrid({
    required double boardHeight,
    required double eventAreaLeft,
  }) {
    return SizedBox(
      height: boardHeight,
      child: Stack(
        children: [
          for (var hour = 0; hour <= DayTimelineMetrics.hoursInDay; hour++)
            _buildHourTick(
              hour: hour,
              boardHeight: boardHeight,
              eventAreaLeft: eventAreaLeft,
            ),
        ],
      ),
    );
  }

  Widget _buildHourTick({
    required int hour,
    required double boardHeight,
    required double eventAreaLeft,
  }) {
    final minute = hour * DayTimelineMetrics.minutesInHour;
    final y = _scale.pixelsForMinutes(minute);
    final isDisabled = hour == DayTimelineMetrics.hoursInDay;
    final labelTop = (y - 7).clamp(0.0, boardHeight - 14);

    return Stack(
      children: [
        Positioned(
          top: y,
          left: eventAreaLeft,
          right: 0,
          child: Container(
            height: 1,
            color: isDisabled ? AppColors.blue50 : AppColors.border,
          ),
        ),
        Positioned(
          top: labelTop,
          left: 0,
          width: DayTimelineMetrics.timeLabelWidth,
          child: Text(
            formatHour(hour),
            textAlign: TextAlign.right,
            style: TextStyle(
              fontSize: 10,
              fontWeight: FontWeight.w600,
              color: isDisabled ? AppColors.slate300 : AppColors.slate400,
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildCurrentTimeMarker({
    required DateTime now,
    required double boardHeight,
  }) {
    final minute = now.hour * DayTimelineMetrics.minutesInHour + now.minute;
    final top = _scale.pixelsForMinutes(minute).clamp(0.0, boardHeight);

    return Positioned(
      top: top - 9,
      left: 0,
      right: 0,
      child: IgnorePointer(
        child: SizedBox(
          height: 18,
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.center,
            children: [
              Container(
                width: DayTimelineMetrics.timeLabelWidth,
                height: 18,
                decoration: BoxDecoration(
                  color: AppColors.red500,
                  borderRadius: BorderRadius.circular(9),
                ),
                child: Center(
                  child: Text(
                    formatHm(now),
                    style: const TextStyle(
                      fontSize: 10,
                      fontWeight: FontWeight.w700,
                      color: Colors.white,
                    ),
                  ),
                ),
              ),
              const SizedBox(width: DayTimelineMetrics.timeLabelGap),
              Expanded(
                child: Container(
                  height: 2,
                  decoration: BoxDecoration(
                    color: AppColors.red500,
                    borderRadius: BorderRadius.circular(99),
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildEventCard({
    required DayEventLayout layout,
    required double boardHeight,
  }) {
    final eventColor = resolveEventColor(
      status: layout.event.status,
      colorHex: layout.event.metadata?.color,
    );
    final isCompact = layout.visualHeight < 20;
    final tapHeight = layout.visualHeight < _minEventTapHeight
        ? _minEventTapHeight
        : layout.visualHeight;
    final top = (layout.top - ((tapHeight - layout.visualHeight) / 2)).clamp(
      0.0,
      boardHeight - tapHeight,
    );
    final visualTop = layout.top - top;

    return Positioned(
      top: top,
      left: layout.left,
      width: layout.width,
      height: tapHeight,
      child: GestureDetector(
        behavior: HitTestBehavior.translucent,
        onTap: () =>
            context.push(AppRoutes.calendarEventDetail(layout.event.id)),
        child: Stack(
          children: [
            Positioned(
              top: visualTop,
              left: 0,
              right: 0,
              height: layout.visualHeight,
              child: Container(
                margin: const EdgeInsets.only(
                  right: DayTimelineMetrics.eventColumnGap,
                ),
                padding: isCompact
                    ? const EdgeInsets.symmetric(horizontal: 4, vertical: 2)
                    : const EdgeInsets.symmetric(horizontal: 6, vertical: 2),
                decoration: BoxDecoration(
                  color: eventColor.withValues(alpha: 0.2),
                  borderRadius: BorderRadius.circular(4),
                  border: Border.all(color: eventColor, width: 1),
                ),
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: [
                    Container(
                      width: 6,
                      height: 6,
                      decoration: BoxDecoration(
                        color: eventColor,
                        shape: BoxShape.circle,
                      ),
                    ),
                    if (!isCompact) const SizedBox(width: 4),
                    if (!isCompact)
                      Expanded(
                        child: Text(
                          layout.event.title,
                          style: TextStyle(
                            fontSize: 11,
                            fontWeight: FontWeight.w500,
                            color: eventColor,
                          ),
                          maxLines: 1,
                          overflow: TextOverflow.ellipsis,
                        ),
                      ),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildBottomDock() {
    return BottomDock(
      activeTab: DockTab.calendar,
      onTodoTap: () {
        _calendarManager.setViewType(CalendarViewType.day);
        context.push(AppRoutes.todoList);
      },
      onCalendarTap: () {
        _calendarManager.setViewType(CalendarViewType.day);
        context.push(AppRoutes.calendarMonth);
      },
      onHomeTap: () => returnToHomePreserveState(context, forceGoHome: true),
    );
  }
}