/*******************************************************************************
 * Copyright (c) 2008 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.internal.p2.ui.sdk;

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.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 {

	Job loadJob = null;

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

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

		} catch (ProvisionException e) {
			MessageDialog.openInformation(null, ProvSDKMessages.Handler_SDKUpdateUIMessageTitle, ProvSDKMessages.Handler_CannotLaunchUI);
		}
		return null;
	}

	void doExecuteAndLoad(final String profileId, boolean preloadRepositories) {
		final QueryableMetadataRepositoryManager queryableManager = new QueryableMetadataRepositoryManager(Policy.getDefault(), false);
		if (preloadRepositories) {
			if (loadJob == null) {

				loadJob = new Job(ProvSDKMessages.InstallNewSoftwareHandler_LoadRepositoryJobLabel) {

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

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

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

	protected boolean preloadRepositories() {
		return true;
	}

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