/*******************************************************************************
 * Copyright (c) 2005, 2018 IBM Corporation and others.
 *
 *  This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License 2.0
 *  which accompanies this distribution, and is available at
 *  https://www.eclipse.org/legal/epl-2.0/
 *
 *  SPDX-License-Identifier: EPL-2.0
 * 
 *  Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.equinox.app;

/**
 * Bootstrap type for an application. An IApplication represent executable entry
 * points into an application. An IApplication can be configured into the
 * Platform's <code>org.eclipse.core.runtime.applications</code>
 * extension-point.
 *
 * <p>
 * Clients may implement this interface.
 * </p>
 * 
 * @since 1.0
 */
public interface IApplication {

	/**
	 * Exit object indicating normal termination
	 */
	public static final Integer EXIT_OK = Integer.valueOf(0);

	/**
	 * Exit object requesting platform restart
	 */
	public static final Integer EXIT_RESTART = Integer.valueOf(23);

	/**
	 * Exit object requesting that the command passed back be executed. Typically
	 * this is used to relaunch Eclipse with different command line arguments. When
	 * the executable is relaunched the command line will be retrieved from the
	 * {@link IApplicationContext#EXIT_DATA_PROPERTY eclipse.exitdata} system
	 * property.
	 */
	public static final Integer EXIT_RELAUNCH = Integer.valueOf(24);

	/**
	 * Starts this application with the given context and returns a result. The
	 * content of the context is unchecked and should conform to the expectations of
	 * the application being invoked. This method can return the value
	 * {@link IApplicationContext#EXIT_ASYNC_RESULT} if the application will deliver
	 * its results asynchronously with the
	 * {@link IApplicationContext#setResult(Object, IApplication)} method; otherwise
	 * this method must not exit until the application is finished and is ready to
	 * exit.
	 * <p>
	 * Applications can return any object they like. If an <code>Integer</code> is
	 * returned it is treated as the program exit code if Eclipse is exiting.
	 * </p>
	 * <p>
	 * Note: This method is called by the platform; it is not intended to be called
	 * directly by clients.
	 * </p>
	 * 
	 * @return the return value of the application
	 * @see #EXIT_OK
	 * @see #EXIT_RESTART
	 * @see #EXIT_RELAUNCH
	 * @see IApplicationContext#EXIT_ASYNC_RESULT
	 * @param context the application context to pass to the application
	 * @exception Exception if there is a problem running this application.
	 */
	public Object start(IApplicationContext context) throws Exception;

	/**
	 * Forces this running application to exit. This method should wait until the
	 * running application is ready to exit. The {@link #start(IApplicationContext)}
	 * should already have exited or should exit very soon after this method exits
	 * <p>
	 * 
	 * This method is only called to force an application to exit. This method will
	 * not be called if an application exits normally from the
	 * {@link #start(IApplicationContext)} method.
	 * <p>
	 * Note: This method is called by the platform; it is not intended to be called
	 * directly by clients.
	 * </p>
	 */
	public void stop();
}
