import 'dart:async';

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:supabase_flutter/supabase_flutter.dart';
import '../models/task.dart';
import '../models/task_assignment.dart';
import 'profile_provider.dart';
import 'supabase_provider.dart';
import 'tickets_provider.dart';
import 'user_offices_provider.dart';

final tasksProvider = StreamProvider<List<Task>>((ref) {
  final client = ref.watch(supabaseClientProvider);
  final profileAsync = ref.watch(currentProfileProvider);
  final ticketsAsync = ref.watch(ticketsProvider);
  final assignmentsAsync = ref.watch(userOfficesProvider);

  final profile = profileAsync.valueOrNull;
  if (profile == null) {
    return Stream.value(const <Task>[]);
  }

  final isGlobal =
      profile.role == 'admin' ||
      profile.role == 'dispatcher' ||
      profile.role == 'it_staff';

  if (isGlobal) {
    return client
        .from('tasks')
        .stream(primaryKey: ['id'])
        .order('queue_order', ascending: true)
        .order('created_at')
        .map((rows) => rows.map(Task.fromMap).toList());
  }

  final allowedTicketIds =
      ticketsAsync.valueOrNull?.map((ticket) => ticket.id).toList() ??
      <String>[];
  final officeIds =
      assignmentsAsync.valueOrNull
          ?.where((assignment) => assignment.userId == profile.id)
          .map((assignment) => assignment.officeId)
          .toSet()
          .toList() ??
      <String>[];

  if (allowedTicketIds.isEmpty && officeIds.isEmpty) {
    return Stream.value(const <Task>[]);
  }

  return client
      .from('tasks')
      .stream(primaryKey: ['id'])
      .order('queue_order', ascending: true)
      .order('created_at')
      .map(
        (rows) => rows.map(Task.fromMap).where((task) {
          final matchesTicket =
              task.ticketId != null && allowedTicketIds.contains(task.ticketId);
          final matchesOffice =
              task.officeId != null && officeIds.contains(task.officeId);
          return matchesTicket || matchesOffice;
        }).toList(),
      );
});

final taskAssignmentsProvider = StreamProvider<List<TaskAssignment>>((ref) {
  final client = ref.watch(supabaseClientProvider);
  return client
      .from('task_assignments')
      .stream(primaryKey: ['task_id', 'user_id'])
      .map((rows) => rows.map(TaskAssignment.fromMap).toList());
});

final taskAssignmentsControllerProvider = Provider<TaskAssignmentsController>((
  ref,
) {
  final client = ref.watch(supabaseClientProvider);
  return TaskAssignmentsController(client);
});

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

class TasksController {
  TasksController(this._client);

  final SupabaseClient _client;

  Future<void> updateTaskStatus({
    required String taskId,
    required String status,
  }) async {
    await _client.from('tasks').update({'status': status}).eq('id', taskId);
  }

  Future<void> createTask({
    required String title,
    required String description,
    required String officeId,
  }) async {
    final actorId = _client.auth.currentUser?.id;
    final data = await _client
        .from('tasks')
        .insert({
          'title': title,
          'description': description,
          'office_id': officeId,
        })
        .select('id')
        .single();
    final taskId = data['id'] as String?;
    if (taskId == null) return;
    unawaited(_notifyCreated(taskId: taskId, actorId: actorId));
  }

  Future<void> _notifyCreated({
    required String taskId,
    required String? actorId,
  }) async {
    try {
      final recipients = await _fetchRoleUserIds(
        roles: const ['dispatcher', 'it_staff'],
        excludeUserId: actorId,
      );
      if (recipients.isEmpty) return;
      final rows = recipients
          .map(
            (userId) => {
              'user_id': userId,
              'actor_id': actorId,
              'task_id': taskId,
              'type': 'created',
            },
          )
          .toList();
      await _client.from('notifications').insert(rows);
    } catch (_) {
      return;
    }
  }

  Future<List<String>> _fetchRoleUserIds({
    required List<String> roles,
    required String? excludeUserId,
  }) async {
    try {
      final data = await _client
          .from('profiles')
          .select('id, role')
          .inFilter('role', roles);
      final rows = data as List<dynamic>;
      final ids = rows
          .map((row) => row['id'] as String?)
          .whereType<String>()
          .where((id) => id.isNotEmpty && id != excludeUserId)
          .toList();
      return ids;
    } catch (_) {
      return [];
    }
  }
}

class TaskAssignmentsController {
  TaskAssignmentsController(this._client);

  final SupabaseClient _client;

  Future<void> replaceAssignments({
    required String taskId,
    required String? ticketId,
    required List<String> newUserIds,
    required List<String> currentUserIds,
  }) async {
    final nextIds = newUserIds.toSet();
    final currentIds = currentUserIds.toSet();
    final toAdd = nextIds.difference(currentIds).toList();
    final toRemove = currentIds.difference(nextIds).toList();

    if (toAdd.isNotEmpty) {
      final rows = toAdd
          .map((userId) => {'task_id': taskId, 'user_id': userId})
          .toList();
      await _client.from('task_assignments').insert(rows);
      await _notifyAssigned(taskId: taskId, ticketId: ticketId, userIds: toAdd);
    }
    if (toRemove.isNotEmpty) {
      await _client
          .from('task_assignments')
          .delete()
          .eq('task_id', taskId)
          .inFilter('user_id', toRemove);
    }
  }

  Future<void> _notifyAssigned({
    required String taskId,
    required String? ticketId,
    required List<String> userIds,
  }) async {
    if (userIds.isEmpty) return;
    try {
      final actorId = _client.auth.currentUser?.id;
      final rows = userIds
          .map(
            (userId) => {
              'user_id': userId,
              'actor_id': actorId,
              'task_id': taskId,
              'ticket_id': ticketId,
              'type': 'assignment',
            },
          )
          .toList();
      await _client.from('notifications').insert(rows);
    } catch (_) {
      return;
    }
  }

  Future<void> removeAssignment({
    required String taskId,
    required String userId,
  }) async {
    await _client
        .from('task_assignments')
        .delete()
        .eq('task_id', taskId)
        .eq('user_id', userId);
  }
}