social-app/apps/lib/data/repositories/friend_repository.dart

import '../../core/network/i_api_client.dart';
import 'models/friend_request.dart';

abstract class FriendRepository {
  Future<List<FriendUser>> getFriends();
  Future<FriendRequest> getRequestById(String friendshipId);
  Future<Map<String, FriendRequest>> getRequestsByIds(
    List<String> friendshipIds,
  );
  Future<FriendRequest> acceptRequest(String friendshipId);
  Future<FriendRequest> declineRequest(String friendshipId);
}

class FriendRepositoryImpl implements FriendRepository {
  final IApiClient _apiClient;
  static const _prefix = '/api/v1/friends';

  FriendRepositoryImpl(this._apiClient);

  @override
  Future<List<FriendUser>> getFriends() async {
    final response = await _apiClient.get<List<dynamic>>(_prefix);
    final data = response.data;
    if (data == null) {
      throw StateError('Invalid getFriends response: empty payload');
    }
    return data
        .map((item) => item as Map<String, dynamic>)
        .map(
          (item) => FriendUser.fromJson(item['friend'] as Map<String, dynamic>),
        )
        .toList(growable: false);
  }

  @override
  Future<FriendRequest> getRequestById(String friendshipId) async {
    final response = await _apiClient.get<Map<String, dynamic>>(
      '$_prefix/requests/$friendshipId',
    );
    final data = response.data;
    if (data == null) {
      throw StateError('Invalid getRequestById response: empty payload');
    }
    return FriendRequest.fromJson(data);
  }

  @override
  Future<Map<String, FriendRequest>> getRequestsByIds(
    List<String> friendshipIds,
  ) async {
    if (friendshipIds.isEmpty) {
      return const <String, FriendRequest>{};
    }

    final pairs = await Future.wait(
      friendshipIds.map((id) async {
        final request = await getRequestById(id);
        return MapEntry(id, request);
      }),
    );

    return Map<String, FriendRequest>.fromEntries(pairs);
  }

  @override
  Future<FriendRequest> acceptRequest(String friendshipId) async {
    final response = await _apiClient.post<Map<String, dynamic>>(
      '$_prefix/requests/$friendshipId/accept',
    );
    final data = response.data;
    if (data == null) {
      throw StateError('Invalid acceptRequest response: empty payload');
    }
    return FriendRequest.fromJson(data);
  }

  @override
  Future<FriendRequest> declineRequest(String friendshipId) async {
    final response = await _apiClient.post<Map<String, dynamic>>(
      '$_prefix/requests/$friendshipId/decline',
    );
    final data = response.data;
    if (data == null) {
      throw StateError('Invalid declineRequest response: empty payload');
    }
    return FriendRequest.fromJson(data);
  }
}