import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:lucide_icons/lucide_icons.dart';
import 'package:social_app/core/l10n/l10n.dart';
import '../../../../app/di/injection.dart';
import '../../../../app/router/app_routes.dart';
import '../../../../core/theme/design_tokens.dart';
import '../../../../shared/widgets/app_loading_indicator.dart';
import '../../../../shared/widgets/app_selection_sheet.dart';
import '../../../../shared/widgets/app_sheet_input_field.dart';
import '../../../../shared/widgets/back_title_page_header.dart';
import '../../../../shared/widgets/toast/toast.dart';
import '../../../../shared/widgets/toast/toast_type.dart';
import 'date_time_picker_sheet.dart';
import '../../../../features/calendar/data/models/schedule_item_model.dart';
import '../../../../features/calendar/data/services/calendar_service.dart';

final _defaultColors = AppColorPalette.light.eventPresetColors;

class CreateEventSheet extends StatefulWidget {
  final DateTime? initialDate;
  final ScheduleItemModel? editingEvent;
  final VoidCallback? onSaved;
  final bool pageMode;

  const CreateEventSheet({
    super.key,
    this.initialDate,
    this.editingEvent,
    this.onSaved,
    this.pageMode = false,
  });

  static Future<void> show(
    BuildContext context, {
    DateTime? initialDate,
    VoidCallback? onSaved,
  }) {
    return showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      backgroundColor: Theme.of(
        context,
      ).colorScheme.surface.withValues(alpha: 0),
      builder: (context) =>
          CreateEventSheet(initialDate: initialDate, onSaved: onSaved),
    );
  }

  static Future<void> edit(
    BuildContext context,
    ScheduleItemModel event, {
    VoidCallback? onSaved,
  }) {
    return showModalBottomSheet(
      context: context,
      isScrollControlled: true,
      backgroundColor: Theme.of(
        context,
      ).colorScheme.surface.withValues(alpha: 0),
      builder: (context) =>
          CreateEventSheet(editingEvent: event, onSaved: onSaved),
    );
  }

  @override
  State<CreateEventSheet> createState() => _CreateEventSheetState();
}

class _CreateEventSheetState extends State<CreateEventSheet>
    with SingleTickerProviderStateMixin {
  static const List<int?> _defaultReminderOptions = [
    null,
    0,
    5,
    10,
    15,
    30,
    60,
    120,
  ];

  late TabController _tabController;
  final _titleController = TextEditingController();
  final _descriptionController = TextEditingController();
  final _locationController = TextEditingController();
  final _notesController = TextEditingController();

  late DateTime _startDate;
  late DateTime _startTime;
  DateTime? _endDate;
  DateTime? _endTime;
  String _selectedColor = '#3B82F6';
  int? _reminderMinutes = 15;
  bool _saving = false;

  bool get _isEditing => widget.editingEvent != null;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 2, vsync: this);

    if (_isEditing) {
      final event = widget.editingEvent!;
      _titleController.text = event.title;
      _descriptionController.text = event.description ?? '';
      _locationController.text = event.metadata?.location ?? '';
      _notesController.text = event.metadata?.notes ?? '';
      _startDate = event.startAt;
      _startTime = event.startAt;
      _endDate = event.endAt;
      _endTime = event.endAt;
      _selectedColor = event.metadata?.color ?? '#3B82F6';
      _reminderMinutes = _sanitizeReminderMinutes(
        event.metadata?.reminderMinutes,
      );
    } else {
      final now = DateTime.now();
      final initial = widget.initialDate;
      final rounded = _roundToNearestMinute(now, 5);
      _startDate = initial != null
          ? DateTime(
              initial.year,
              initial.month,
              initial.day,
              rounded.hour,
              rounded.minute,
            )
          : rounded;
      _startTime = _startDate;
      _endDate = _startDate;
      _endTime = _startDate.add(const Duration(hours: 1));
    }
  }

  @override
  void dispose() {
    _tabController.dispose();
    _titleController.dispose();
    _descriptionController.dispose();
    _locationController.dispose();
    _notesController.dispose();
    super.dispose();
  }

  DateTime _roundToNearestMinute(DateTime dt, int interval) {
    final totalMinutes = dt.hour * 60 + dt.minute;
    final rounded = ((totalMinutes / interval).round() * interval);
    final hours = rounded ~/ 60;
    final minutes = rounded % 60;
    final dayOffset = hours >= 24 ? 1 : 0;
    final newHour = hours % 24;
    return DateTime(dt.year, dt.month, dt.day + dayOffset, newHour, minutes);
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    if (widget.pageMode) {
      return GestureDetector(
        behavior: HitTestBehavior.translucent,
        onTap: () => FocusScope.of(context).unfocus(),
        child: Container(
          color: colorScheme.surface,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              _buildPageHeader(),
              _buildTabBar(),
              Expanded(child: _buildTabContent()),
            ],
          ),
        ),
      );
    }

    return AnimatedPadding(
      duration: const Duration(milliseconds: 150),
      curve: Curves.easeOut,
      padding: EdgeInsets.only(
        bottom: MediaQuery.of(context).viewInsets.bottom,
      ),
      child: Container(
        height: MediaQuery.of(context).size.height * 0.85,
        decoration: BoxDecoration(
          color: colorScheme.surface,
          borderRadius: BorderRadius.vertical(top: Radius.circular(20)),
        ),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            const SizedBox(height: AppSpacing.sm),
            Center(
              child: Container(
                width: AppSpacing.xl + AppSpacing.sm,
                height: AppSpacing.xs,
                decoration: BoxDecoration(
                  color: colorScheme.outlineVariant,
                  borderRadius: BorderRadius.circular(AppRadius.full),
                ),
              ),
            ),
            const SizedBox(height: AppSpacing.sm),
            _buildHeader(),
            _buildTabBar(),
            Expanded(child: _buildTabContent()),
          ],
        ),
      ),
    );
  }

  Widget _buildPageHeader() {
    final colorScheme = Theme.of(context).colorScheme;
    return BackTitlePageHeader(
      title: _isEditing
          ? context.l10n.calendarCreateEditTitle
          : context.l10n.calendarCreateNewTitle,
      onBack: () => _closeSheet(),
      trailing: ValueListenableBuilder<TextEditingValue>(
        valueListenable: _titleController,
        builder: (context, value, child) {
          final enabled = value.text.trim().isNotEmpty && !_saving;
          return SizedBox(
            height: AppSpacing.xxl * 2,
            child: TextButton(
              onPressed: enabled ? _saveEvent : null,
              style: TextButton.styleFrom(
                padding: const EdgeInsets.symmetric(horizontal: AppSpacing.md),
                minimumSize: const Size(AppSpacing.none, AppSpacing.none),
                tapTargetSize: MaterialTapTargetSize.shrinkWrap,
              ),
              child: _saving
                  ? const AppLoadingIndicator(
                      variant: AppLoadingVariant.button,
                      size: 18,
                      trackColor: null,
                    )
                  : Text(
                      context.l10n.commonSave,
                      style: TextStyle(
                        fontSize: 16,
                        fontWeight: FontWeight.w600,
                        color: enabled
                            ? colorScheme.primary
                            : colorScheme.outline,
                      ),
                    ),
            ),
          );
        },
      ),
    );
  }

  Widget _buildHeader() {
    final colorScheme = Theme.of(context).colorScheme;
    return Container(
      height: 56,
      padding: const EdgeInsets.symmetric(horizontal: 16),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          SizedBox(
            width: AppSpacing.xxl * 2,
            height: AppSpacing.xxl * 2,
            child: TextButton(
              onPressed: _closeSheet,
              style: TextButton.styleFrom(
                padding: const EdgeInsets.all(AppSpacing.none),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(AppRadius.full),
                ),
              ),
              child: Icon(
                LucideIcons.x,
                size: AppSpacing.xxl,
                color: colorScheme.onSurfaceVariant,
              ),
            ),
          ),
          Text(
            _isEditing
                ? context.l10n.calendarCreateEditTitle
                : context.l10n.calendarCreateNewTitle,
            style: TextStyle(
              fontSize: 17,
              fontWeight: FontWeight.w600,
              color: colorScheme.onSurface,
            ),
          ),
          ValueListenableBuilder<TextEditingValue>(
            valueListenable: _titleController,
            builder: (context, value, child) {
              final enabled = value.text.trim().isNotEmpty && !_saving;
              return SizedBox(
                height: AppSpacing.xxl * 2,
                child: TextButton(
                  onPressed: enabled ? _saveEvent : null,
                  style: TextButton.styleFrom(
                    padding: const EdgeInsets.symmetric(
                      horizontal: AppSpacing.md,
                    ),
                    minimumSize: const Size(AppSpacing.none, AppSpacing.none),
                    tapTargetSize: MaterialTapTargetSize.shrinkWrap,
                  ),
                  child: _saving
                      ? const AppLoadingIndicator(
                          variant: AppLoadingVariant.button,
                          size: 18,
                          trackColor: null,
                        )
                      : Text(
                          context.l10n.commonSave,
                          style: TextStyle(
                            fontSize: 17,
                            fontWeight: FontWeight.w600,
                            color: enabled
                                ? colorScheme.primary
                                : colorScheme.outline,
                          ),
                        ),
                ),
              );
            },
          ),
        ],
      ),
    );
  }

  Widget _buildTabBar() {
    final colorScheme = Theme.of(context).colorScheme;
    return Container(
      decoration: BoxDecoration(
        border: Border(bottom: BorderSide(color: colorScheme.outlineVariant)),
      ),
      child: TabBar(
        controller: _tabController,
        labelColor: colorScheme.primary,
        unselectedLabelColor: colorScheme.onSurfaceVariant,
        indicatorColor: colorScheme.primary,
        tabs: [
          Tab(text: context.l10n.calendarCreateTabBasic),
          Tab(text: context.l10n.calendarCreateTabAdvanced),
        ],
      ),
    );
  }

  Widget _buildTabContent() {
    return TabBarView(
      controller: _tabController,
      children: [_buildBasicTab(), _buildAdvancedTab()],
    );
  }

  Widget _buildBasicTab() {
    return SingleChildScrollView(
      keyboardDismissBehavior: ScrollViewKeyboardDismissBehavior.onDrag,
      padding: const EdgeInsets.all(16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _buildTextField(
            context.l10n.calendarCreateFieldTitle,
            _titleController,
            context.l10n.calendarCreateFieldTitleHint,
          ),
          const SizedBox(height: 20),
          _buildDateTimePicker(
            context.l10n.calendarCreateFieldStart,
            _startDate,
            _startTime,
            (date, time) {
              setState(() {
                _startDate = date;
                _startTime = time;
                if (_endDate != null && _endTime != null) {
                  final endDateTime = _composeDateTime(_endDate!, _endTime!);
                  final startDateTime = _composeDateTime(date, time);
                  if (endDateTime.isBefore(startDateTime) ||
                      endDateTime.isAtSameMomentAs(startDateTime)) {
                    _setEndDateTime(_defaultEndDateTime(startDateTime));
                  }
                }
              });
            },
          ),
          const SizedBox(height: 20),
          _buildDateTimePicker(
            context.l10n.calendarCreateFieldEnd,
            _endDate ?? _startDate,
            _endTime ?? _startTime,
            (date, time) {
              setState(() {
                final startDateTime = _composeDateTime(_startDate, _startTime);
                final endDateTime = _composeDateTime(date, time);
                if (endDateTime.isBefore(startDateTime) ||
                    endDateTime.isAtSameMomentAs(startDateTime)) {
                  Toast.show(
                    context,
                    context.l10n.calendarCreateInvalidTimeRange,
                    type: ToastType.error,
                  );
                  _setEndDateTime(_defaultEndDateTime(startDateTime));
                } else {
                  _setEndDateTime(endDateTime);
                }
              });
            },
            isOptional: true,
          ),
        ],
      ),
    );
  }

  DateTime _composeDateTime(DateTime date, DateTime time) {
    return DateTime(date.year, date.month, date.day, time.hour, time.minute);
  }

  DateTime _defaultEndDateTime(DateTime startDateTime) {
    return startDateTime.add(const Duration(hours: 1));
  }

  void _setEndDateTime(DateTime value) {
    _endDate = DateTime(value.year, value.month, value.day);
    _endTime = DateTime(
      value.year,
      value.month,
      value.day,
      value.hour,
      value.minute,
    );
  }

  Widget _buildAdvancedTab() {
    return SingleChildScrollView(
      keyboardDismissBehavior: ScrollViewKeyboardDismissBehavior.onDrag,
      padding: const EdgeInsets.all(16),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          _buildTextField(
            context.l10n.calendarCreateFieldDescription,
            _descriptionController,
            context.l10n.calendarCreateFieldDescriptionHint,
          ),
          const SizedBox(height: 20),
          _buildTextField(
            context.l10n.calendarCreateFieldLocation,
            _locationController,
            context.l10n.calendarCreateFieldLocationHint,
          ),
          const SizedBox(height: 20),
          _buildReminderPicker(),
          const SizedBox(height: 20),
          _buildColorPicker(),
          const SizedBox(height: 20),
          _buildTextField(
            context.l10n.calendarDetailNotes,
            _notesController,
            context.l10n.calendarCreateFieldNotesHint,
            maxLines: 3,
          ),
        ],
      ),
    );
  }

  Widget _buildTextField(
    String label,
    TextEditingController controller,
    String hint, {
    int maxLines = 1,
    bool autofocus = false,
  }) {
    return AppSheetInputField(
      controller: controller,
      label: label,
      hint: hint,
      maxLines: maxLines,
      autofocus: autofocus,
    );
  }

  Widget _buildDateTimePicker(
    String label,
    DateTime date,
    DateTime time,
    Function(DateTime, DateTime) onChanged, {
    bool isOptional = false,
    DateTime? minTime,
  }) {
    final colorScheme = Theme.of(context).colorScheme;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          isOptional ? context.l10n.calendarCreateOptionalField(label) : label,
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w600,
            color: colorScheme.onSurfaceVariant,
          ),
        ),
        const SizedBox(height: 8),
        InkWell(
          onTap: () async {
            final picked = await _pickDateTime(date, time, minTime: minTime);
            if (picked == null) {
              return;
            }
            onChanged(picked.$1, picked.$2);
          },
          borderRadius: BorderRadius.circular(AppRadius.md),
          child: Container(
            padding: const EdgeInsets.all(AppSpacing.md),
            decoration: BoxDecoration(
              color: colorScheme.surfaceContainerLowest,
              borderRadius: BorderRadius.circular(AppRadius.md),
              border: Border.all(color: colorScheme.outlineVariant),
            ),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [
                Icon(
                  LucideIcons.calendar,
                  size: 16,
                  color: colorScheme.onSurfaceVariant,
                ),
                const SizedBox(width: AppSpacing.sm),
                Expanded(
                  child: Text(
                    _formatDateTimeLabel(date, time),
                    style: TextStyle(
                      fontSize: 15,
                      fontWeight: FontWeight.w500,
                      color: colorScheme.onSurface,
                    ),
                  ),
                ),
                Icon(
                  LucideIcons.chevronRight,
                  size: 16,
                  color: colorScheme.outline,
                ),
              ],
            ),
          ),
        ),
      ],
    );
  }

  String _formatDateTimeLabel(DateTime date, DateTime time) {
    return context.l10n.calendarCreateDateTimeLabel(
      date.year,
      date.month,
      date.day,
      time.hour.toString().padLeft(2, '0'),
      time.minute.toString().padLeft(2, '0'),
    );
  }

  Future<(DateTime, DateTime)?> _pickDateTime(
    DateTime date,
    DateTime time, {
    DateTime? minTime,
  }) async {
    final result = await showModalBottomSheet<(DateTime, DateTime)>(
      context: context,
      backgroundColor: Theme.of(
        context,
      ).colorScheme.surface.withValues(alpha: 0),
      isScrollControlled: true,
      builder: (context) => DateTimePickerSheet(
        initialDate: date,
        initialTime: time,
        minTime: minTime,
      ),
    );
    return result;
  }

  Widget _buildColorPicker() {
    final colorScheme = Theme.of(context).colorScheme;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          context.l10n.calendarDetailColor,
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w600,
            color: colorScheme.onSurfaceVariant,
          ),
        ),
        const SizedBox(height: 8),
        Row(
          children: _defaultColors.map((color) {
            final colorHex =
                '#${color.toARGB32().toRadixString(16).substring(2).toUpperCase()}';
            final isSelected = _selectedColor == colorHex;
            final checkColor =
                ThemeData.estimateBrightnessForColor(color) == Brightness.dark
                ? Colors.white
                : Colors.black;
            return GestureDetector(
              onTap: () => setState(() => _selectedColor = colorHex),
              child: Container(
                margin: const EdgeInsets.only(right: 12),
                width: 32,
                height: 32,
                decoration: BoxDecoration(
                  color: color,
                  shape: BoxShape.circle,
                  border: isSelected
                      ? Border.all(color: colorScheme.onSurface, width: 2)
                      : null,
                ),
                child: isSelected
                    ? Icon(Icons.check, size: 16, color: checkColor)
                    : null,
              ),
            );
          }).toList(),
        ),
      ],
    );
  }

  Widget _buildReminderPicker() {
    final colorScheme = Theme.of(context).colorScheme;
    String labelOf(int? value) {
      if (value == null) {
        return context.l10n.calendarCreateReminderNone;
      }
      if (value == 0) {
        return context.l10n.calendarDetailReminderOnTime;
      }
      return context.l10n.calendarDetailReminderBeforeMinutes(value);
    }

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          context.l10n.calendarCreateReminderTime,
          style: TextStyle(
            fontSize: 14,
            fontWeight: FontWeight.w600,
            color: colorScheme.onSurfaceVariant,
          ),
        ),
        const SizedBox(height: 8),
        InkWell(
          onTap: () async {
            final options = _buildReminderOptions();
            final selected = await showAppSelectionSheet<int?>(
              context,
              title: context.l10n.calendarCreatePickReminderTime,
              items: options
                  .map((v) => AppSelectionItem(value: v, label: labelOf(v)))
                  .toList(),
              selectedValue: _reminderMinutes,
            );
            if (selected != null) {
              setState(() {
                _reminderMinutes = selected;
              });
            }
          },
          borderRadius: BorderRadius.circular(AppRadius.md),
          child: Container(
            width: double.infinity,
            padding: const EdgeInsets.all(AppSpacing.md),
            decoration: BoxDecoration(
              color: colorScheme.surfaceContainerLowest,
              borderRadius: BorderRadius.circular(AppRadius.md),
              border: Border.all(color: colorScheme.outlineVariant),
            ),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [
                Expanded(
                  child: Text(
                    labelOf(_reminderMinutes),
                    style: TextStyle(
                      fontSize: 15,
                      fontWeight: FontWeight.w500,
                      color: colorScheme.onSurface,
                    ),
                  ),
                ),
                Icon(
                  LucideIcons.chevronRight,
                  size: 16,
                  color: colorScheme.outline,
                ),
              ],
            ),
          ),
        ),
      ],
    );
  }

  int? _sanitizeReminderMinutes(int? minutes) {
    return (minutes != null && minutes >= 0) ? minutes : null;
  }

  List<int?> _buildReminderOptions() {
    final current = _sanitizeReminderMinutes(_reminderMinutes);
    final nonNull = _defaultReminderOptions.whereType<int>().toSet();
    if (current != null) {
      nonNull.add(current);
    }

    final sorted = nonNull.toList()..sort();
    return [null, ...sorted];
  }

  Future<void> _saveEvent() async {
    if (_titleController.text.trim().isEmpty || _saving) return;
    setState(() {
      _saving = true;
    });

    final startAt = DateTime(
      _startDate.year,
      _startDate.month,
      _startDate.day,
      _startTime.hour,
      _startTime.minute,
    );

    DateTime? endAt;
    if (_endDate != null && _endTime != null) {
      endAt = DateTime(
        _endDate!.year,
        _endDate!.month,
        _endDate!.day,
        _endTime!.hour,
        _endTime!.minute,
      );
    }

    final metadata = ScheduleMetadata(
      color: _selectedColor,
      location: _locationController.text.trim().isNotEmpty
          ? _locationController.text.trim()
          : null,
      notes: _notesController.text.trim().isNotEmpty
          ? _notesController.text.trim()
          : null,
      reminderMinutes: _reminderMinutes,
      attachments: const [],
      version: widget.editingEvent?.metadata?.version ?? 1,
    );

    final event = ScheduleItemModel(
      id: _isEditing
          ? widget.editingEvent!.id
          : 'evt_${DateTime.now().millisecondsSinceEpoch}',
      ownerId: widget.editingEvent?.ownerId ?? '',
      title: _titleController.text.trim(),
      description: _descriptionController.text.trim().isNotEmpty
          ? _descriptionController.text.trim()
          : null,
      startAt: startAt,
      endAt: endAt,
      metadata: metadata,
    );

    var saved = false;

    try {
      final service = sl<CalendarService>();

      if (_isEditing) {
        await service.updateEvent(event);
      } else {
        await service.addEvent(event);
      }

      saved = true;

      widget.onSaved?.call();
    } catch (e) {
      if (mounted) {
        Toast.show(
          context,
          context.l10n.todoSaveFailed('$e'),
          type: ToastType.error,
        );
      }
    } finally {
      if (mounted) {
        setState(() {
          _saving = false;
        });
      }
    }

    if (saved && mounted) {
      _closeSheet(result: true);
    }
  }

  void _closeSheet({Object? result}) {
    if (!mounted) {
      return;
    }

    final navigator = Navigator.of(context);
    if (navigator.canPop()) {
      navigator.pop(result);
      return;
    }

    final router = GoRouter.of(context);
    if (router.canPop()) {
      context.pop(result);
      return;
    }

    context.go(AppRoutes.homeMain);
  }
}