Unreal

// Your own server mints the token: never put a client secret in a game.
void ALingaraEmbedSnippetActor::HandleTokenNeeded(const FLingaraTokenNeeded& Event)
{
	const TSharedRef<IHttpRequest, ESPMode::ThreadSafe> Request = FHttpModule::Get().CreateRequest();
	Request->SetVerb(TEXT("POST"));
	Request->SetURL(TokenUrl);
	Request->SetHeader(TEXT("Content-Type"), TEXT("application/json"));
	Request->SetContentAsString(TEXT("{}"));
	Request->OnProcessRequestComplete().BindUObject(this, &ALingaraEmbedSnippetActor::HandleTokenResponse);
	Request->ProcessRequest();
}

void ALingaraEmbedSnippetActor::HandleTokenResponse(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bConnected)
{
	ELingaraCallResult Result;
	FLingaraEmbedError Error;
	TSharedPtr<FJsonObject> Body;
	FString Token;
	FString ExpiresAt;
	const bool bOk = bConnected && Response.IsValid() && EHttpResponseCodes::IsOk(Response->GetResponseCode())
		&& FJsonSerializer::Deserialize(TJsonReaderFactory<TCHAR>::Create(Response->GetContentAsString()), Body)
		&& Body->TryGetStringField(TEXT("token"), Token) && Body->TryGetStringField(TEXT("expires_at"), ExpiresAt);
	if (bOk)
	{
		Lingara()->ProvideToken(Token, ExpiresAt, Result, Error);
	}
	else
	{
		// Fail the waiting calls now rather than at the core's timeout.
		Lingara()->TokenUnavailable(TEXT("the token endpoint failed"), Result, Error);
	}
}

// The subsystem drains the core's queue from its own tick (at most
// MaxEventsPerTick a frame, from Project Settings): bind the events you use.
void ALingaraEmbedSnippetActor::BeginPlay()
{
	Super::BeginPlay();
	ULingaraEmbedSubsystem* Subsystem = Lingara();
	Subsystem->OnTokenNeeded.AddDynamic(this, &ALingaraEmbedSnippetActor::HandleTokenNeeded);
	Subsystem->OnNpcTurn.AddDynamic(this, &ALingaraEmbedSnippetActor::HandleNpcTurn);
	Subsystem->OnPractice.AddDynamic(this, &ALingaraEmbedSnippetActor::HandlePractice);
	Subsystem->OnError.AddDynamic(this, &ALingaraEmbedSnippetActor::HandleError);

	FLingaraEmbedConfig Config;
	Config.MaxEventsPerTick = 256;
	ELingaraCallResult Result;
	FLingaraEmbedError Error;
	Subsystem->Start(Config, Result, Error);
}

void ALingaraEmbedSnippetActor::HandleError(const FLingaraEmbedError& Error)
{
	UE_LOG(LogTemp, Warning, TEXT("Lingara %s: %s"), *Error.KindName, *Error.Message);
}