class FooCoroutinesClient(private val fooUrl: String, val userAgent: String) {

    val coroutineScope = CoroutineScope(Dispatchers.Default)

    private val cache: LoadingCache<String, Deferred<FooResponse>> =
        Caffeine.newBuilder()
            .maximumSize(1000)
            .expireAfterWrite(30, TimeUnit.SECONDS)
            .build { key -> coroutineScope.async { doFetchFoo(key) } }

    val client = HttpClient(Apache) {
        engine {
            connectionRequestTimeout = 400
        }
        install(HttpTimeout){
            connectTimeoutMillis = 400
            socketTimeoutMillis = 100
        }
        install(JsonFeature) {
            serializer = KotlinxSerializer(
                Json(
                    JsonConfiguration(
                        isLenient = true,
                        ignoreUnknownKeys = true,
                        serializeSpecialFloatingPointValues = true,
                        useArrayPolymorphism = true
                    )
                )
            )
        }
    }

    suspend fun doFetchFoo(query: String): FooResponse {
        return client.request {
            header("User-Agent", userAgent)
            parameter("query", query)
            url("$fooUrl/v1/foo")
        }
    }

    suspend fun fetchFoo(query: String): FooResponse {
        return cache.get(query)?.await()!!
    }
}