/*
 * Copyright DataStax, Inc.
 *
 * Licensed 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 com.datastax.oss.driver.example.guava.internal;

import com.datastax.oss.driver.api.core.session.Request;
import com.datastax.oss.driver.api.core.type.reflect.GenericType;
import com.datastax.oss.driver.internal.core.context.InternalDriverContext;
import com.datastax.oss.driver.internal.core.session.DefaultSession;
import com.datastax.oss.driver.internal.core.session.RequestProcessor;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import java.util.concurrent.CompletionStage;

/**
 * Wraps a {@link RequestProcessor} that returns {@link CompletionStage}s and converts them to a
 * {@link ListenableFuture}s.
 *
 * @param <T> The type of request
 * @param <U> The type of responses enclosed in the future response.
 */
public class GuavaRequestAsyncProcessor<T extends Request, U>
    implements RequestProcessor<T, ListenableFuture<U>> {

  private final RequestProcessor<T, CompletionStage<U>> subProcessor;

  private final GenericType resultType;

  private final Class<?> requestClass;

  GuavaRequestAsyncProcessor(
      RequestProcessor<T, CompletionStage<U>> subProcessor,
      Class<?> requestClass,
      GenericType resultType) {
    this.subProcessor = subProcessor;
    this.requestClass = requestClass;
    this.resultType = resultType;
  }

  @Override
  public boolean canProcess(Request request, GenericType resultType) {
    return requestClass.isInstance(request) && resultType.equals(this.resultType);
  }

  @Override
  public ListenableFuture<U> process(
      T request, DefaultSession session, InternalDriverContext context, String sessionLogPrefix) {
    SettableFuture<U> future = SettableFuture.create();
    subProcessor
        .process(request, session, context, sessionLogPrefix)
        .whenComplete(
            (r, ex) -> {
              if (ex != null) {
                future.setException(ex);
              } else {
                future.set(r);
              }
            });
    return future;
  }

  @Override
  public ListenableFuture<U> newFailure(RuntimeException error) {
    return Futures.immediateFailedFuture(error);
  }
}
