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A type-safe HTTP client for Android and Java.
There is a newer version: 2.11.0
/*
 * Copyright (C) 2016 Square, 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 retrofit2;

import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.concurrent.CompletableFuture;
import javax.annotation.Nullable;
import org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement;

@IgnoreJRERequirement // Only added when CompletableFuture is available (Java 8+ / Android API 24+).
final class CompletableFutureCallAdapterFactory extends CallAdapter.Factory {
  static final CallAdapter.Factory INSTANCE = new CompletableFutureCallAdapterFactory();

  @Override public @Nullable CallAdapter get(
      Type returnType, Annotation[] annotations, Retrofit retrofit) {
    if (getRawType(returnType) != CompletableFuture.class) {
      return null;
    }
    if (!(returnType instanceof ParameterizedType)) {
      throw new IllegalStateException("CompletableFuture return type must be parameterized"
          + " as CompletableFuture or CompletableFuture");
    }
    Type innerType = getParameterUpperBound(0, (ParameterizedType) returnType);

    if (getRawType(innerType) != Response.class) {
      // Generic type is not Response. Use it for body-only adapter.
      return new BodyCallAdapter<>(innerType);
    }

    // Generic type is Response. Extract T and create the Response version of the adapter.
    if (!(innerType instanceof ParameterizedType)) {
      throw new IllegalStateException("Response must be parameterized"
          + " as Response or Response");
    }
    Type responseType = getParameterUpperBound(0, (ParameterizedType) innerType);
    return new ResponseCallAdapter<>(responseType);
  }

  @IgnoreJRERequirement
  private static final class BodyCallAdapter implements CallAdapter> {
    private final Type responseType;

    BodyCallAdapter(Type responseType) {
      this.responseType = responseType;
    }

    @Override public Type responseType() {
      return responseType;
    }

    @Override public CompletableFuture adapt(final Call call) {
      final CompletableFuture future = new CallCancelCompletableFuture<>(call);

      call.enqueue(new Callback() {
        @Override public void onResponse(Call call, Response response) {
          if (response.isSuccessful()) {
            future.complete(response.body());
          } else {
            future.completeExceptionally(new HttpException(response));
          }
        }

        @Override public void onFailure(Call call, Throwable t) {
          future.completeExceptionally(t);
        }
      });

      return future;
    }
  }

  @IgnoreJRERequirement
  private static final class ResponseCallAdapter
      implements CallAdapter>> {
    private final Type responseType;

    ResponseCallAdapter(Type responseType) {
      this.responseType = responseType;
    }

    @Override public Type responseType() {
      return responseType;
    }

    @Override public CompletableFuture> adapt(final Call call) {
      final CompletableFuture> future = new CallCancelCompletableFuture<>(call);

      call.enqueue(new Callback() {
        @Override public void onResponse(Call call, Response response) {
          future.complete(response);
        }

        @Override public void onFailure(Call call, Throwable t) {
          future.completeExceptionally(t);
        }
      });

      return future;
    }
  }

  private static final class CallCancelCompletableFuture extends CompletableFuture {
    private final Call call;

    CallCancelCompletableFuture(Call call) {
      this.call = call;
    }

    @Override public boolean cancel(boolean mayInterruptIfRunning) {
      if (mayInterruptIfRunning) {
        call.cancel();
      }
      return super.cancel(mayInterruptIfRunning);
    }
  }
}