package org.junit.runner.notification;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import org.junit.internal.AssumptionViolatedException;

import org.junit.runner.Description;

import org.junit.runner.Result;

/**

 * If you write custom runners, you may need to notify JUnit of your progress running tests.

 * Do this by invoking the <code>RunNotifier</code> passed to your implementation of

 * {@link org.junit.runner.Runner#run(RunNotifier)}. Future evolution of this class is likely to 

 * move {@link #fireTestRunStarted(Description)} and {@link #fireTestRunFinished(Result)}

 * to a separate class since they should only be called once per run.

 */

public class RunNotifier {

	private final List<RunListener> fListeners= new ArrayList<RunListener>();

	private boolean fPleaseStop= false;

	/** Internal use only

	 */

	public void addListener(RunListener listener) {

		fListeners.add(listener);

	}

	/** Internal use only

	 */

	public void removeListener(RunListener listener) {

		fListeners.remove(listener);

	}

	private abstract class SafeNotifier {

		void run() {

			for (Iterator<RunListener> all= fListeners.iterator(); all.hasNext();)

				try {

					notifyListener(all.next());

				} catch (Exception e) {

					all.remove(); // Remove the offending listener first to avoid an infinite loop

					fireTestFailure(new Failure(Description.TEST_MECHANISM, e));

				}

		}

		abstract protected void notifyListener(RunListener each) throws Exception;

	}

	/**

	 * Do not invoke. 

	 */

	public void fireTestRunStarted(final Description description) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testRunStarted(description);

			};

		}.run();

	}

	/**

	 * Do not invoke.

	 */

	public void fireTestRunFinished(final Result result) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testRunFinished(result);

			};

		}.run();

	}

	/**

	 * Invoke to tell listeners that an atomic test is about to start.

	 * @param description the description of the atomic test (generally a class and method name)

	 * @throws StoppedByUserException thrown if a user has requested that the test run stop

	 */

	public void fireTestStarted(final Description description) throws StoppedByUserException {

		if (fPleaseStop)

			throw new StoppedByUserException();

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testStarted(description);

			};

		}.run();

	}

	/**

	 * Invoke to tell listeners that an atomic test failed.

	 * @param failure the description of the test that failed and the exception thrown

	 */

	public void fireTestFailure(final Failure failure) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testFailure(failure);

			};

		}.run();

	}

	/**

	 * Invoke to tell listeners that an atomic test flagged that it assumed

	 * something false.

	 * 

	 * @param failure

	 *            the description of the test that failed and the

	 *            {@link AssumptionViolatedException} thrown

	 */

	public void fireTestAssumptionFailed(final Failure failure) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testAssumptionFailure(failure);

			};

		}.run();

	}

	/**

	 * Invoke to tell listeners that an atomic test was ignored.

	 * @param description the description of the ignored test

	 */

	public void fireTestIgnored(final Description description) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testIgnored(description);

			}

		}.run();

	}

	/**

	 * Invoke to tell listeners that an atomic test finished. Always invoke 

	 * {@link #fireTestFinished(Description)} if you invoke {@link #fireTestStarted(Description)} 

	 * as listeners are likely to expect them to come in pairs.

	 * @param description the description of the test that finished

	 */

	public void fireTestFinished(final Description description) {

		new SafeNotifier() {

			@Override

			protected void notifyListener(RunListener each) throws Exception {

				each.testFinished(description);

			};

		}.run();

	}

	/**

	 * Ask that the tests run stop before starting the next test. Phrased politely because

	 * the test currently running will not be interrupted. It seems a little odd to put this

	 * functionality here, but the <code>RunNotifier</code> is the only object guaranteed 

	 * to be shared amongst the many runners involved.

	 */

	public void pleaseStop() {

		fPleaseStop= true;

	}

	/**

	 * Internal use only. The Result's listener must be first.

	 */

	public void addFirstListener(RunListener listener) {

		fListeners.add(0, listener);

	}

}