/*
 * Copyright 2016 Google LLC
 *
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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package com.google.api.gax.grpc;

import com.google.api.core.ApiFuture;
import com.google.api.core.ListenableFutureToApiFuture;
import com.google.api.gax.rpc.ApiCallContext;
import com.google.api.gax.rpc.UnaryCallable;
import com.google.common.base.Preconditions;
import io.grpc.ClientCall;
import io.grpc.MethodDescriptor;
import io.grpc.stub.ClientCalls;

/**
 * {@code GrpcDirectCallable} creates gRPC calls.
 *
 * <p>Package-private for internal use.
 */
class GrpcDirectCallable<RequestT, ResponseT> extends UnaryCallable<RequestT, ResponseT> {
  private final MethodDescriptor<RequestT, ResponseT> descriptor;
  private final boolean awaitTrailers;

  GrpcDirectCallable(MethodDescriptor<RequestT, ResponseT> descriptor, boolean awaitTrailers) {
    this.descriptor = Preconditions.checkNotNull(descriptor);
    this.awaitTrailers = awaitTrailers;
  }

  @Override
  public ApiFuture<ResponseT> futureCall(RequestT request, ApiCallContext inputContext) {
    Preconditions.checkNotNull(request);
    Preconditions.checkNotNull(inputContext);

    ClientCall<RequestT, ResponseT> clientCall = GrpcClientCalls.newCall(descriptor, inputContext);

    if (awaitTrailers) {
      return new ListenableFutureToApiFuture<>(ClientCalls.futureUnaryCall(clientCall, request));
    } else {
      return GrpcClientCalls.eagerFutureUnaryCall(clientCall, request);
    }
  }

  @Override
  public String toString() {
    return String.format("direct(%s)", descriptor);
  }
}