/*
 * 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.
 *
 * Copyright 2012-2018 the original author or authors.
 */
package org.assertj.core.matcher;

import org.assertj.core.util.Throwables;
import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Matcher;

/**
 * Generic Hamcrest {@link Matcher} that reuses AssertJ assertions.
 * <p>
 * Overriding classes should only implement {@link AssertionMatcher#assertion(Object)} method as  
 * {@link Matcher#matches(Object)} and {@link Matcher#describeTo(Description)} are provided. 
 * <p>
 * If the matcher fails, the description will contain the stacktrace of the first failed assertion.
 * <p>
 * Example with Mockito:
 * <pre><code class='java'> verify(customerRepository).save(argThat(new AssertionMatcher&lt;Customer&gt;() {
 *     &#64;Override
 *     public void assertion(Customer actual) throws AssertionError {
 *       assertThat(actual).hasName(&quot;John&quot;)
 *                         .hasAge(30);
 *     }
 *   })
 * );</code></pre>
 * 
 * @param <T> the type of the object to test
 *
 * @author Tomasz Kalkosiński
 * @since 2.7.0 / 3.7.0
 */
public abstract class AssertionMatcher<T> extends BaseMatcher<T> {
  private AssertionError firstError;

  /**
   * {@inheritDoc}
   */
  @SuppressWarnings("unchecked")
  @Override
  public boolean matches(Object argument) {
    T actual = (T) argument;
    try {
      assertion(actual);
      return true;
    } catch (AssertionError e) {
      firstError = e;
      return false;
    }
  }

  /**
   * Perform the assertions implemented in this method when the {@link AssertionMatcher} is used as an Hamcrest {@link Matcher}.
   *
   * If the matcher fails, the description will contain the stacktrace of the first failed assertion.
   * <p>
   * Example with Mockito:
   * <pre><code class='java'> verify(customerRepository).save(argThat(new AssertionMatcher&lt;Customer&gt;() {
   *     &#64;Override
   *     public void assertion(Customer actual) throws AssertionError {
   *       assertThat(actual).hasName(&quot;John&quot;)
   *                         .hasAge(30);
   *     }
   *   })
   * );</code></pre>
   *
   * @param actual assertion object
   * @throws AssertionError if the assertion object fails assertion
   */
  public abstract void assertion(T actual) throws AssertionError;

  /**
   * {@inheritDoc}
   */
  @Override
  public void describeTo(Description description) {
    if (firstError != null) {
      description.appendText("AssertionError with message: ");
      description.appendText(firstError.getMessage());
      description.appendText(String.format("%n%nStacktrace was: "));
      description.appendText(Throwables.getStackTrace(firstError));
    }
  }
}