/*
 * Copyright 2018 Confluent Inc.
 *
 * Licensed under the Confluent Community License (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.confluent.io/confluent-community-license
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OF ANY KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations under the License.
 */

package io.confluent.ksql.rest.server.resources;

import com.google.common.base.Suppliers;
import io.confluent.ksql.rest.entity.ServerInfo;
import io.confluent.ksql.rest.entity.Versions;
import io.confluent.ksql.services.ServiceContext;
import io.confluent.ksql.util.KsqlConfig;
import io.confluent.ksql.util.Version;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("/info")
@Produces({Versions.KSQL_V1_JSON, MediaType.APPLICATION_JSON})
public class ServerInfoResource {
  private static final long DESCRIBE_CLUSTER_TIMEOUT_SECONDS = 30;

  private final Supplier<ServerInfo> serverInfo;

  public ServerInfoResource(final ServiceContext serviceContext, final KsqlConfig ksqlConfig) {
    this.serverInfo = Suppliers.memoize(
        () -> new ServerInfo(
            Version.getVersion(),
            getKafkaClusterId(serviceContext),
            ksqlConfig.getString(KsqlConfig.KSQL_SERVICE_ID_CONFIG)
        )
    )::get;
  }

  private static String getKafkaClusterId(final ServiceContext serviceContext) {
    try {
      return serviceContext.getAdminClient()
          .describeCluster()
          .clusterId()
          .get(DESCRIBE_CLUSTER_TIMEOUT_SECONDS, TimeUnit.SECONDS);
    } catch (final Exception e) {
      throw new RuntimeException("Failed to get Kafka cluster information", e);
    }
  }

  @GET
  public Response get() {
    return Response.ok(serverInfo.get()).build();
  }
}
