/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.statefun.flink.core.httpfn;

import static org.apache.flink.statefun.flink.core.httpfn.OkHttpUnixSocketBridge.configureUnixDomainSocket;

import java.net.URI;
import javax.annotation.Nullable;
import okhttp3.HttpUrl;
import okhttp3.OkHttpClient;
import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.DeserializationFeature;
import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.flink.shaded.jackson2.com.fasterxml.jackson.databind.node.ObjectNode;
import org.apache.flink.statefun.flink.common.SetContextClassLoader;
import org.apache.flink.statefun.flink.core.reqreply.ClassLoaderSafeRequestReplyClient;
import org.apache.flink.statefun.flink.core.reqreply.RequestReplyClient;
import org.apache.flink.statefun.flink.core.reqreply.RequestReplyClientFactory;

public final class DefaultHttpRequestReplyClientFactory implements RequestReplyClientFactory {

  /** Unknown fields in client properties are silently ignored. */
  private static final ObjectMapper OBJ_MAPPER =
      new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

  /** lazily initialized by {@link #createTransportClient} */
  @Nullable private OkHttpClient sharedClient;

  private volatile boolean shutdown;

  @Override
  public RequestReplyClient createTransportClient(ObjectNode transportProperties, URI endpointUrl) {
    final DefaultHttpRequestReplyClient client = createClient(transportProperties, endpointUrl);

    if (Thread.currentThread().getContextClassLoader() == getClass().getClassLoader()) {
      return client;
    } else {
      return new ClassLoaderSafeRequestReplyClient(client);
    }
  }

  @Override
  public void cleanup() {
    if (!shutdown) {
      shutdown = true;
      OkHttpUtils.closeSilently(sharedClient);
    }
  }

  private DefaultHttpRequestReplyClient createClient(
      ObjectNode transportProperties, URI endpointUrl) {
    try (SetContextClassLoader ignored = new SetContextClassLoader(this)) {
      if (sharedClient == null) {
        sharedClient = OkHttpUtils.newClient();
      }
      final OkHttpClient.Builder clientBuilder = sharedClient.newBuilder();

      final DefaultHttpRequestReplyClientSpec transportClientSpec =
          parseTransportProperties(transportProperties);

      clientBuilder.callTimeout(transportClientSpec.getTimeouts().getCallTimeout());
      clientBuilder.connectTimeout(transportClientSpec.getTimeouts().getConnectTimeout());
      clientBuilder.readTimeout(transportClientSpec.getTimeouts().getReadTimeout());
      clientBuilder.writeTimeout(transportClientSpec.getTimeouts().getWriteTimeout());

      HttpUrl url;
      if (UnixDomainHttpEndpoint.validate(endpointUrl)) {
        UnixDomainHttpEndpoint endpoint = UnixDomainHttpEndpoint.parseFrom(endpointUrl);

        url =
            new HttpUrl.Builder()
                .scheme("http")
                .host("unused")
                .addPathSegment(endpoint.pathSegment)
                .build();

        configureUnixDomainSocket(clientBuilder, endpoint.unixDomainFile);
      } else {
        url = HttpUrl.get(endpointUrl);
      }

      return new DefaultHttpRequestReplyClient(url, clientBuilder.build(), () -> shutdown);
    }
  }

  private static DefaultHttpRequestReplyClientSpec parseTransportProperties(
      ObjectNode transportClientProperties) {
    try {
      return OBJ_MAPPER.treeToValue(
          transportClientProperties, DefaultHttpRequestReplyClientSpec.class);
    } catch (Exception e) {
      throw new RuntimeException(
          "Unable to parse transport client properties when creating client: ", e);
    }
  }
}