AuthRepository.kt

interface AuthRepository{
    fun isSignedIn(): Flow<Result<Boolean>>
    fun isRegistered(token: String): Flow<Result<Boolean>>
    fun signIn(user: User): Flow<Result<Boolean>>
    fun register(user: User): Flow<Result<Boolean>>
}

class AuthRepoImpl(val remoteService: MyService){
    override fun isSignedIn(): Flow<Result<Boolean>> = 
    callbackFlow {
        trySend(Result.Loading)
        val listener = remoteService.isSignedIn()
            .onComplete{ result: Boolean ->
                trySend(Result.Success(result))}
            .onFailure{ result: Boolean ->
                trySend(Result.Error("checking auth state failed"))}
        awaitClose{
            listener.close()
        }
    }

    override fun isRegistered(token: String): Flow<Result<Boolean>> = 
    callbackFlow {
        trySend(Result.Loading)
        val listener = remoteService.findUserWithToken(token)
            .onComplete { response : MyServiceResponse ->
                trySend(Result.Success(!response.isNullOrEmpty())) }
            .onFailure { result: Boolean ->
                trySend(Result.Error("checking auth registration failed")) }
        awaitClose {
            listener.close()
        }
    }

    override fun signIn(user: User): Flow<Result<Boolean>> = 
    callbackFlow {
        trySend(Result.Loading)
        val listener = remoteService.signIn(user.token, user.toJson())
            .onComplete { result: MyServiceResponse ->
                trySend(Result.Success(result.isSuccess)) }
            .onFailure { result: Boolean ->
                trySend(Result.Error("Signin failed")) }
        awaitClose {
            listener.close()
        }
    }

    override fun register(user: User): Flow<Result<Boolean>> = 
    callbackFlow {
        trySend(Result.Loading)
        val listener = remoteService.signIn(user.toJson())
            .onComplete { result: MyServiceResponse ->
                trySend(Result.Success(result.isSuccess)) }
            .onFailure { result: Boolean ->
                trySend(Result.Error("Registration failed")) }
        awaitClose {
            listener.close()
        }
    }
}