/*******************************************************************************
 * Copyright (c) 2008, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.equinox.p2.examples.rcp.sdkbundlevisibility.p2;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.runtime.*;
import org.eclipse.core.runtime.jobs.*;
import org.eclipse.equinox.internal.provisional.p2.core.ProvisionException;
import org.eclipse.equinox.internal.provisional.p2.engine.IProfileRegistry;
import org.eclipse.equinox.internal.provisional.p2.ui.ProvUI;
import org.eclipse.equinox.internal.provisional.p2.ui.QueryableMetadataRepositoryManager;
import org.eclipse.equinox.internal.provisional.p2.ui.policy.Policy;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.swt.custom.BusyIndicator;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.PlatformUI;

/**
 * PreloadingRepositoryHandler provides background loading of repositories
 * before executing the provisioning handler.
 * 
 * @since 3.5
 */
abstract class PreloadingRepositoryHandler extends AbstractHandler {

	Object LOAD_FAMILY = new Object();

	/**
	 * The constructor.
	 */
	public PreloadingRepositoryHandler() {
		// constructor
	}

	/**
	 * Execute the command.
	 */
	public Object execute(ExecutionEvent event) {
		final String profileId = IProfileRegistry.SELF;
		BusyIndicator.showWhile(getShell().getDisplay(), new Runnable() {
			public void run() {
				doExecuteAndLoad(profileId, preloadRepositories());
			}
		});
		return null;
	}

	void doExecuteAndLoad(final String profileId, boolean preloadRepositories) {
		// cancel any load that is already running
		Job.getJobManager().cancel(LOAD_FAMILY);
		final QueryableMetadataRepositoryManager queryableManager = new QueryableMetadataRepositoryManager(
				Policy.getDefault().getQueryContext(), false);
		if (preloadRepositories) {
			Job loadJob = new Job(
					Messages.InstallNewSoftwareHandler_LoadRepositoryJobLabel) {

				protected IStatus run(IProgressMonitor monitor) {
					queryableManager.loadAll(monitor);
					return Status.OK_STATUS;
				}

				public boolean belongsTo(Object family) {
					return family == LOAD_FAMILY;
				}

			};
			if (waitForPreload()) {
				loadJob.addJobChangeListener(new JobChangeAdapter() {
					public void done(IJobChangeEvent event) {
						if (PlatformUI.isWorkbenchRunning())
							if (event.getResult().isOK()) {
								PlatformUI.getWorkbench().getDisplay()
										.asyncExec(new Runnable() {
											public void run() {
												doExecute(profileId,
														queryableManager);
											}
										});
							}
					}
				});
				loadJob.setUser(true);
				loadJob.schedule();

			} else {
				loadJob.setSystem(true);
				loadJob.setUser(false);
				loadJob.schedule();
				doExecute(profileId, queryableManager);
			}
		} else {
			doExecute(profileId, queryableManager);
		}
	}

	protected abstract void doExecute(String profileId,
			QueryableMetadataRepositoryManager manager);

	protected boolean preloadRepositories() {
		return true;
	}

	protected boolean waitForPreload() {
		return true;
	}

	/**
	 * Return a shell appropriate for parenting dialogs of this handler.
	 * 
	 * @return a Shell
	 */
	protected Shell getShell() {
		return ProvUI.getDefaultParentShell();
	}
}