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/*-
 * -\-\-
 * hamcrest-future
 * --
 * Copyright (C) 2016 Spotify AB
 * --
 * 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.spotify.hamcrest.future;

import java.util.Objects;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import org.hamcrest.Description;
import org.hamcrest.Matcher;
import org.hamcrest.TypeSafeDiagnosingMatcher;

class ExceptionallyCompletedFuture extends TypeSafeDiagnosingMatcher> {

  private final Matcher matcher;

  /**
   * Creates a new ExceptionallyCompletedFuture where the exception that the Future finished with
   * matches the given Matcher.
   */
  ExceptionallyCompletedFuture(final Matcher matcher) {
    this.matcher = Objects.requireNonNull(matcher);
  }

  @Override
  protected boolean matchesSafely(final Future future, final Description mismatchDescription) {
    if (future.isDone()) {
      if (future.isCancelled()) {
        mismatchDescription.appendText("a future that was cancelled");
        return false;
      } else {
        final T value;
        try {
          value = future.get();
        } catch (ExecutionException e) {
          final Throwable cause = e.getCause();
          if (matcher.matches(cause)) {
            return true;
          } else {
            mismatchDescription.appendText("a future completed exceptionally with ");
            matcher.describeMismatch(cause, mismatchDescription);
            return false;
          }
        } catch (InterruptedException e) {
          throw new AssertionError("This should never happen because the future is completed.");
        }

        mismatchDescription
            .appendText("a future that completed to a value that was ")
            .appendValue(value);
        return false;
      }
    } else {
      mismatchDescription.appendText("a future that was not done");
      return false;
    }
  }

  @Override
  public void describeTo(final Description description) {
    description
        .appendText("a future that completed with an exception that ")
        .appendDescriptionOf(matcher);
  }
}