import 'dart:async';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:supabase_flutter/supabase_flutter.dart';

import '../models/app_settings.dart';
import '../models/duty_schedule.dart';
import '../models/swap_request.dart';
import 'profile_provider.dart';
import 'supabase_provider.dart';
import 'stream_recovery.dart';
import 'realtime_controller.dart';

final geofenceProvider = FutureProvider<GeofenceConfig?>((ref) async {
  final client = ref.watch(supabaseClientProvider);
  final data = await client
      .from('app_settings')
      .select()
      .eq('key', 'geofence')
      .maybeSingle();
  if (data == null) return null;
  final setting = AppSetting.fromMap(data);
  return GeofenceConfig.fromJson(setting.value);
});

/// Toggle to show/hide past schedules. Defaults to false (hide past).
final showPastSchedulesProvider = StateProvider<bool>((ref) => false);

final dutySchedulesProvider = StreamProvider<List<DutySchedule>>((ref) {
  final client = ref.watch(supabaseClientProvider);
  // Only recreate stream when user id changes (not on other profile edits).
  final profileId = ref.watch(
    currentProfileProvider.select((p) => p.valueOrNull?.id),
  );
  if (profileId == null) {
    return Stream.value(const <DutySchedule>[]);
  }

  // All roles now see all schedules (RLS updated in migration)
  final wrapper = StreamRecoveryWrapper<DutySchedule>(
    stream: client
        .from('duty_schedules')
        .stream(primaryKey: ['id'])
        .order('start_time'),
    onPollData: () async {
      final data = await client
          .from('duty_schedules')
          .select()
          .order('start_time');
      return data.map(DutySchedule.fromMap).toList();
    },
    fromMap: DutySchedule.fromMap,
    channelName: 'duty_schedules',
    onStatusChanged: ref.read(realtimeControllerProvider).handleChannelStatus,
  );

  ref.onDispose(wrapper.dispose);

  // Immediate poll so any changes that happened while this provider was
  // not alive (e.g. a swap was accepted on another device) are reflected
  // right away — before the 3-second periodic timer fires.
  wrapper.pollNow();

  // Periodic safety-net: keep polling every 3 s so that ownership changes
  // (swap accepted → user_id updated on duty_schedules) are always picked
  // up even if Supabase Realtime misses the event.
  final dutyRefreshTimer = Timer.periodic(const Duration(seconds: 3), (_) {
    wrapper.pollNow();
  });
  ref.onDispose(dutyRefreshTimer.cancel);

  return wrapper.stream.map((result) => result.data);
});

/// Fetch duty schedules by a list of IDs (used by UI when swap requests reference
/// schedules that are not included in the current user's `dutySchedulesProvider`).
final dutySchedulesByIdsProvider =
    FutureProvider.family<List<DutySchedule>, List<String>>((ref, ids) async {
      if (ids.isEmpty) return const <DutySchedule>[];
      final client = ref.watch(supabaseClientProvider);
      final quoted = ids.map((id) => '"$id"').join(',');
      final inList = '($quoted)';
      final rows =
          await client
                  .from('duty_schedules')
                  .select()
                  .filter('id', 'in', inList)
              as List<dynamic>;
      return rows
          .map((r) => DutySchedule.fromMap(r as Map<String, dynamic>))
          .toList();
    });

/// Fetch upcoming duty schedules for a specific user (used by swap UI to
/// let the requester pick a concrete target shift owned by the recipient).
final dutySchedulesForUserProvider =
    FutureProvider.family<List<DutySchedule>, String>((ref, userId) async {
      final client = ref.watch(supabaseClientProvider);
      final nowIso = DateTime.now().toUtc().toIso8601String();
      final rows =
          await client
                  .from('duty_schedules')
                  .select()
                  .eq('user_id', userId)
                  /* exclude past schedules by ensuring the shift has not ended */
                  .gte('end_time', nowIso)
                  .order('start_time')
              as List<dynamic>;
      return rows
          .map((r) => DutySchedule.fromMap(r as Map<String, dynamic>))
          .toList();
    });

final swapRequestsProvider = StreamProvider<List<SwapRequest>>((ref) {
  final client = ref.watch(supabaseClientProvider);
  // Only recreate stream when user id or role changes.
  final profileId = ref.watch(
    currentProfileProvider.select((p) => p.valueOrNull?.id),
  );
  final profileRole = ref.watch(
    currentProfileProvider.select((p) => p.valueOrNull?.role),
  );
  if (profileId == null) {
    return Stream.value(const <SwapRequest>[]);
  }

  final isAdmin =
      profileRole == 'admin' ||
      profileRole == 'programmer' ||
      profileRole == 'dispatcher';

  final wrapper = StreamRecoveryWrapper<SwapRequest>(
    stream: isAdmin
        ? client
              .from('swap_requests')
              .stream(primaryKey: ['id'])
              .order('created_at', ascending: false)
        : client
              .from('swap_requests')
              .stream(primaryKey: ['id'])
              .order('created_at', ascending: false),
    onPollData: () async {
      final data = await client
          .from('swap_requests')
          .select()
          .inFilter('status', ['pending', 'admin_review'])
          .order('created_at', ascending: false);
      return data.map(SwapRequest.fromMap).toList();
    },
    fromMap: SwapRequest.fromMap,
    channelName: 'swap_requests',
    onStatusChanged: ref.read(realtimeControllerProvider).handleChannelStatus,
  );

  ref.onDispose(wrapper.dispose);

  // Immediate poll: fetch fresh data right away so any status changes that
  // happened while this provider was not alive are reflected instantly,
  // before the 3-second periodic timer fires for the first time.
  wrapper.pollNow();

  // Periodic safety-net: keep polling every 3 s to catch any status changes
  // that Supabase Realtime may have missed (e.g. when the swap_requests table
  // is not yet in the supabase_realtime publication).
  final refreshTimer = Timer.periodic(const Duration(seconds: 3), (_) {
    wrapper.pollNow();
  });
  ref.onDispose(refreshTimer.cancel);

  return wrapper.stream.map((result) {
    // only return requests that are still actionable; once a swap has been
    // accepted or rejected we no longer need to bubble it up to the UI for
    // either party.  admins still see "admin_review" rows so they can act on
    // escalated cases.
    return result.data.where((row) {
      // admins see all swaps; standard users only see swaps they're in
      if (!isAdmin && !(row.requesterId == profileId || row.recipientId == profileId)) {
        return false;
      }
      // only keep pending and admin_review statuses
      return row.status == 'pending' || row.status == 'admin_review';
    }).toList();
  });
});

/// IDs of swap requests that were acted on locally (accepted, rejected, etc.).
/// Kept as a global provider so the set survives tab switches — widget state
/// is disposed when the user navigates away from My Schedule.
final locallyRemovedSwapIdsProvider = StateProvider<Set<String>>((ref) => {});

/// IDs of duty_schedules owned by the current user that were created by an accepted swap.
final swappedScheduleIdsProvider = Provider<Set<String>>((ref) {
  final schedules = ref.watch(dutySchedulesProvider).valueOrNull ?? [];
  return {
    for (final s in schedules)
      if (s.swapRequestId != null) s.id,
  };
});

final workforceControllerProvider = Provider<WorkforceController>((ref) {
  final client = ref.watch(supabaseClientProvider);
  return WorkforceController(client);
});

class WorkforceController {
  WorkforceController(this._client);

  final SupabaseClient _client;

  Future<void> generateSchedule({
    required DateTime startDate,
    required DateTime endDate,
  }) async {
    await _client.rpc(
      'generate_duty_schedule',
      params: {
        'start_date': _formatDate(startDate),
        'end_date': _formatDate(endDate),
      },
    );
  }

  Future<void> insertSchedules(List<Map<String, dynamic>> schedules) async {
    if (schedules.isEmpty) return;
    await _client.from('duty_schedules').insert(schedules);
  }

  Future<String?> checkIn({
    required String dutyScheduleId,
    required double lat,
    required double lng,
  }) async {
    final data = await _client.rpc(
      'duty_check_in',
      params: {'p_duty_id': dutyScheduleId, 'p_lat': lat, 'p_lng': lng},
    );
    return data as String?;
  }

  Future<String?> requestSwap({
    required String requesterScheduleId,
    required String targetScheduleId,
    required String recipientId,
  }) async {
    final data = await _client.rpc(
      'request_shift_swap',
      params: {
        'p_shift_id': requesterScheduleId,
        'p_target_shift_id': targetScheduleId,
        'p_recipient_id': recipientId,
      },
    );
    return data as String?;
  }

  Future<void> respondSwap({
    required String swapId,
    required String action,
  }) async {
    await _client.rpc(
      'respond_shift_swap',
      params: {'p_swap_id': swapId, 'p_action': action},
    );
  }

  /// Reassign the recipient of a swap request. Only admins/dispatchers are
  /// expected to call this; the DB RLS and RPCs will additionally enforce rules.
  Future<void> reassignSwap({
    required String swapId,
    required String newRecipientId,
  }) async {
    // Prefer using an RPC for server-side validation, but update directly here
    await _client
        .from('swap_requests')
        .update({
          'recipient_id': newRecipientId,
          'status': 'pending',
          'updated_at': DateTime.now().toUtc().toIso8601String(),
        })
        .eq('id', swapId);
  }

  Future<void> updateSchedule({
    required String scheduleId,
    required String userId,
    required String shiftType,
    required DateTime startTime,
    required DateTime endTime,
  }) async {
    await _client
        .from('duty_schedules')
        .update({
          'user_id': userId,
          'shift_type': shiftType,
          'start_time': startTime.toUtc().toIso8601String(),
          'end_time': endTime.toUtc().toIso8601String(),
        })
        .eq('id', scheduleId);
  }

  String _formatDate(DateTime value) {
    final date = DateTime(value.year, value.month, value.day);
    final month = date.month.toString().padLeft(2, '0');
    final day = date.day.toString().padLeft(2, '0');
    return '${date.year}-$month-$day';
  }
}