import '../../models/group_model.dart';
import '../../models/group_member_model.dart';
import '../interfaces/group_service.dart';
import 'api_client.dart';

/// Real API implementation.
/// NOTE: The backend has no list-groups or list-members endpoint.
/// Groups and members are tracked in memory per session.
class GroupApiService implements GroupService {
  final ApiClient _client;
  final List<GroupModel> _sessionGroups = [];
  final Map<String, List<GroupMemberModel>> _sessionMembers = {};

  GroupApiService(this._client);

  @override
  Future<List<GroupModel>> getGroups() async {
    return List.unmodifiable(_sessionGroups);
  }

  @override
  Future<GroupModel> createGroup(String name, String? description) async {
    final body = <String, dynamic>{'name': name};
    if (description != null && description.isNotEmpty) {
      body['description'] = description;
    }
    final data = await _client.post('/groups/', body);
    final group = GroupModel.fromJson(data as Map<String, dynamic>);
    _sessionGroups.add(group);
    _sessionMembers[group.id] = [];
    return group;
  }

  @override
  Future<GroupMemberModel> addMember(
    String groupId,
    String userId,
    GroupRole role,
  ) async {
    final data = await _client.post('/groups/$groupId/members', {
      'user_id': userId,
      'role': role.apiValue,
    });
    final member = GroupMemberModel.fromJson(data as Map<String, dynamic>);
    _sessionMembers.putIfAbsent(groupId, () => []).add(member);

    // Update member count on the cached group
    final idx = _sessionGroups.indexWhere((g) => g.id == groupId);
    if (idx != -1) {
      _sessionGroups[idx] = _sessionGroups[idx].copyWith(
        memberCount: (_sessionMembers[groupId]?.length ?? 1),
      );
    }
    return member;
  }

  @override
  Future<List<GroupMemberModel>> getGroupMembers(String groupId) async {
    return List.unmodifiable(_sessionMembers[groupId] ?? []);
  }
}