import 'package:flutter/material.dart';
import 'package:lucide_icons/lucide_icons.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

import '../../core/theme.dart';
import '../../data/models/calendar_event.dart';
import '../../providers/api_client_provider.dart';
import '../../providers/calendar_provider.dart';

class EventFormSheet extends ConsumerStatefulWidget {
  /// null = create mode; non-null = edit mode.
  final CalendarEvent? event;

  /// Pre-fills start date in create mode. Ignored in edit mode.
  final DateTime? initialDate;

  final CalendarNotifier notifier;

  const EventFormSheet({
    super.key,
    required this.event,
    required this.initialDate,
    required this.notifier,
  });

  @override
  ConsumerState<EventFormSheet> createState() => _EventFormSheetState();
}

class _EventFormSheetState extends ConsumerState<EventFormSheet> {
  late final TextEditingController _titleCtrl;
  late final TextEditingController _descCtrl;
  late final TextEditingController _locationCtrl;

  late DateTime _startDt;
  DateTime? _endDt;
  late bool _allDay;
  String? _recurrence; // null = None; one of the FREQ= strings otherwise
  String _color = '';
  bool _saving = false;

  bool get _isCreate => widget.event == null;

  /// Maps RRULE string (or null) to display label for the dropdown.
  static const Map<String?, String> _knownRrules = {
    null: 'None',
    'FREQ=DAILY': 'Daily',
    'FREQ=WEEKLY': 'Weekly',
    'FREQ=MONTHLY': 'Monthly',
    'FREQ=YEARLY': 'Yearly',
  };

  /// True when editing an event whose RRULE is not one of the 5 known patterns.
  bool get _isCustomRrule =>
      widget.event?.recurrence != null &&
      !_knownRrules.containsKey(widget.event!.recurrence);

  static const List<String> _presetColors = [
    '#EF4444',
    '#F59E0B',
    '#10B981',
    '#7C3AED',
    '#8B5CF6',
    '#EC4899',
  ];

  @override
  void initState() {
    super.initState();
    final e = widget.event;
    _titleCtrl = TextEditingController(text: e?.title ?? '');
    _descCtrl = TextEditingController(text: e?.description ?? '');
    _locationCtrl = TextEditingController(text: e?.location ?? '');

    if (e != null) {
      _startDt = e.startDt.toLocal();
      _endDt = e.endDt?.toLocal();
      _allDay = e.allDay;
      // Custom RRULEs are displayed as read-only; leave _recurrence = null.
      _recurrence = _isCustomRrule ? null : e.recurrence;
      _color = e.color;
    } else {
      final base = widget.initialDate ?? DateTime.now();
      final now = DateTime.now();
      final hour = now.minute >= 30 ? (now.hour + 1) % 24 : now.hour;
      _startDt = DateTime(base.year, base.month, base.day, hour);
      _allDay = false;
      _recurrence = null;
    }
  }

  @override
  void dispose() {
    _titleCtrl.dispose();
    _descCtrl.dispose();
    _locationCtrl.dispose();
    super.dispose();
  }

  // ── Save ──────────────────────────────────────────────────────────────────

  Future<void> _save() async {
    if (_titleCtrl.text.trim().isEmpty) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('Title is required.')),
      );
      return;
    }
    setState(() => _saving = true);
    try {
      // Preserve unrecognised RRULEs unchanged on save.
      final rrule = _isCustomRrule ? widget.event!.recurrence : _recurrence;
      final payload = <String, dynamic>{
        'title': _titleCtrl.text.trim(),
        'start_dt': _startDt.toUtc().toIso8601String(),
        if (_endDt != null) 'end_dt': _endDt!.toUtc().toIso8601String(),
        'all_day': _allDay,
        'description': _descCtrl.text.trim(),
        'location': _locationCtrl.text.trim(),
        'color': _color,
        'recurrence': rrule,
      };
      final repo = ref.read(eventsRepositoryProvider);
      if (_isCreate) {
        final created = await repo.createEvent(payload);
        widget.notifier.addEvent(created);
      } else {
        final updated = await repo.updateEvent(widget.event!.id, payload);
        widget.notifier.updateEvent(updated);
      }
      if (mounted) Navigator.of(context).pop();
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Failed to save event.')),
        );
      }
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  // ── Delete ────────────────────────────────────────────────────────────────

  Future<void> _delete() async {
    final confirmed = await showDialog<bool>(
      context: context,
      builder: (dialogContext) => AlertDialog(
        title: const Text('Delete this event?'),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(dialogContext, false),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(dialogContext, true),
            style: TextButton.styleFrom(
              foregroundColor: Theme.of(dialogContext).extension<ActionColors>()!.destructive,
            ),
            child: const Text('Delete'),
          ),
        ],
      ),
    );
    if (confirmed != true || !mounted) return;
    setState(() => _saving = true);
    try {
      await ref.read(eventsRepositoryProvider).deleteEvent(widget.event!.id);
      widget.notifier.removeEvent(widget.event!.id, widget.event!.startDt);
      if (mounted) Navigator.of(context).pop();
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Failed to delete event.')),
        );
      }
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  // ── Date/time pickers ─────────────────────────────────────────────────────

  Future<void> _pickStartDate() async {
    final d = await showDatePicker(
      context: context,
      initialDate: _startDt,
      firstDate: DateTime(2000),
      lastDate: DateTime(2100),
    );
    if (d != null) {
      setState(() {
        _startDt = DateTime(
            d.year, d.month, d.day, _startDt.hour, _startDt.minute);
      });
    }
  }

  Future<void> _pickStartTime() async {
    final t = await showTimePicker(
      context: context,
      initialTime: TimeOfDay.fromDateTime(_startDt),
    );
    if (t != null) {
      setState(() {
        _startDt = DateTime(
            _startDt.year, _startDt.month, _startDt.day, t.hour, t.minute);
      });
    }
  }

  Future<void> _pickEndDate() async {
    final d = await showDatePicker(
      context: context,
      initialDate: _endDt ?? _startDt,
      firstDate: DateTime(2000),
      lastDate: DateTime(2100),
    );
    if (d != null) {
      setState(() {
        final prev = _endDt ?? _startDt;
        _endDt =
            DateTime(d.year, d.month, d.day, prev.hour, prev.minute);
      });
    }
  }

  Future<void> _pickEndTime() async {
    final t = await showTimePicker(
      context: context,
      initialTime: TimeOfDay.fromDateTime(_endDt ?? _startDt),
    );
    if (t != null) {
      setState(() {
        final prev = _endDt ?? _startDt;
        _endDt = DateTime(
            prev.year, prev.month, prev.day, t.hour, t.minute);
      });
    }
  }

  // ── Formatting helpers ────────────────────────────────────────────────────

  String _fmtDate(DateTime dt) {
    const months = [
      'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
      'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec',
    ];
    return '${months[dt.month - 1]} ${dt.day}, ${dt.year}';
  }

  String _fmtTime(DateTime dt) =>
      '${dt.hour.toString().padLeft(2, '0')}:${dt.minute.toString().padLeft(2, '0')}';

  // ── Build ─────────────────────────────────────────────────────────────────

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding:
          EdgeInsets.only(bottom: MediaQuery.of(context).viewInsets.bottom),
      child: SingleChildScrollView(
        padding: const EdgeInsets.fromLTRB(16, 16, 16, 32),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            // Header
            Row(
              children: [
                Text(
                  _isCreate ? 'New Event' : 'Edit Event',
                  style: Theme.of(context).textTheme.titleLarge,
                ),
                const Spacer(),
                if (!_isCreate)
                  IconButton(
                    icon: const Icon(LucideIcons.trash2),
                    color: Theme.of(context).colorScheme.error,
                    onPressed: _saving ? null : _delete,
                  ),
              ],
            ),
            const SizedBox(height: 16),

            // Title
            TextField(
              controller: _titleCtrl,
              decoration: const InputDecoration(
                labelText: 'Title',
                border: OutlineInputBorder(),
              ),
              textCapitalization: TextCapitalization.sentences,
            ),
            const SizedBox(height: 12),

            // All-day toggle
            SwitchListTile(
              title: const Text('All day'),
              value: _allDay,
              onChanged: (v) => setState(() => _allDay = v),
              contentPadding: EdgeInsets.zero,
            ),

            // Start date
            ListTile(
              contentPadding: EdgeInsets.zero,
              leading: const Icon(LucideIcons.calendarDays),
              title: Text(_fmtDate(_startDt)),
              subtitle: const Text('Start date'),
              onTap: _pickStartDate,
            ),

            // Start time (hidden when all-day)
            if (!_allDay)
              ListTile(
                contentPadding: EdgeInsets.zero,
                leading: const Icon(LucideIcons.clock),
                title: Text(_fmtTime(_startDt)),
                subtitle: const Text('Start time'),
                onTap: _pickStartTime,
              ),

            // End date
            ListTile(
              contentPadding: EdgeInsets.zero,
              leading: const Icon(LucideIcons.calendarCheck),
              title: Text(
                  _endDt != null ? _fmtDate(_endDt!) : 'No end date'),
              subtitle: const Text('End date'),
              onTap: _pickEndDate,
              trailing: _endDt != null
                  ? IconButton(
                      icon: const Icon(LucideIcons.x),
                      onPressed: () => setState(() => _endDt = null),
                    )
                  : null,
            ),

            // End time (hidden when all-day or no end date)
            if (!_allDay && _endDt != null)
              ListTile(
                contentPadding: EdgeInsets.zero,
                leading: const Icon(LucideIcons.clock),
                title: Text(_fmtTime(_endDt!)),
                subtitle: const Text('End time'),
                onTap: _pickEndTime,
              ),

            const SizedBox(height: 8),

            // Repeat — show read-only tile for custom RRULEs
            if (_isCustomRrule)
              ListTile(
                contentPadding: EdgeInsets.zero,
                leading: const Icon(LucideIcons.repeat),
                title: const Text('Custom (read-only)'),
                subtitle: Text(widget.event!.recurrence ?? ''),
              )
            else
              Row(
                children: [
                  const Icon(LucideIcons.repeat),
                  const SizedBox(width: 16),
                  DropdownButton<String?>(
                    value: _recurrence,
                    underline: const SizedBox.shrink(),
                    items: _knownRrules.entries
                        .map((entry) => DropdownMenuItem<String?>(
                              value: entry.key,
                              child: Text(entry.value),
                            ))
                        .toList(),
                    onChanged: (v) => setState(() => _recurrence = v),
                  ),
                ],
              ),

            const SizedBox(height: 12),

            // Description
            TextField(
              controller: _descCtrl,
              decoration: const InputDecoration(
                labelText: 'Description',
                border: OutlineInputBorder(),
              ),
              maxLines: 3,
              textCapitalization: TextCapitalization.sentences,
            ),
            const SizedBox(height: 12),

            // Location
            TextField(
              controller: _locationCtrl,
              decoration: const InputDecoration(
                labelText: 'Location',
                border: OutlineInputBorder(),
              ),
            ),
            const SizedBox(height: 16),

            // Color chips
            Text('Color', style: Theme.of(context).textTheme.labelMedium),
            const SizedBox(height: 8),
            Row(
              children: [
                // "No color" chip
                GestureDetector(
                  onTap: () => setState(() => _color = ''),
                  child: Container(
                    width: 32,
                    height: 32,
                    margin: const EdgeInsets.only(right: 8),
                    decoration: BoxDecoration(
                      shape: BoxShape.circle,
                      border: Border.all(
                        color: _color.isEmpty
                            ? Theme.of(context).colorScheme.primary
                            : Theme.of(context).colorScheme.outline,
                        width: _color.isEmpty ? 2 : 1,
                      ),
                    ),
                    child: const Icon(LucideIcons.ban, size: 16),
                  ),
                ),
                ..._presetColors.map((hex) {
                  final c =
                      Color(int.parse(hex.replaceFirst('#', '0xFF')));
                  return GestureDetector(
                    onTap: () => setState(() => _color = hex),
                    child: Container(
                      width: 32,
                      height: 32,
                      margin: const EdgeInsets.only(right: 8),
                      decoration: BoxDecoration(
                        color: c,
                        shape: BoxShape.circle,
                        border: _color == hex
                            ? Border.all(
                                color: Theme.of(context)
                                    .colorScheme
                                    .primary,
                                width: 2,
                              )
                            : null,
                      ),
                    ),
                  );
                }),
              ],
            ),

            const SizedBox(height: 24),

            // Save button — Moss action-primary per Hybrid rule
            SizedBox(
              width: double.infinity,
              child: FilledButton(
                style: FilledButton.styleFrom(
                  backgroundColor: Theme.of(context).extension<ActionColors>()!.primary,
                ),
                onPressed: _saving ? null : _save,
                child: _saving
                    ? const SizedBox(
                        height: 20,
                        width: 20,
                        child: CircularProgressIndicator(strokeWidth: 2),
                      )
                    : Text(_isCreate ? 'Create' : 'Save'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}