/*******************************************************************************
 * Copyright (c) 2016 Red Hat Inc. 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:
 *     Mickael Istria (Red Hat Inc.) - initial API and implementation
 *******************************************************************************/
package org.eclipse.epp.internal.mpc.ui.discovery;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.IJobChangeEvent;
import org.eclipse.core.runtime.jobs.JobChangeAdapter;
import org.eclipse.core.runtime.jobs.JobGroup;
import org.eclipse.epp.internal.mpc.ui.MarketplaceClientUiPlugin;
import org.eclipse.epp.internal.mpc.ui.Messages;
import org.eclipse.epp.mpc.core.model.INode;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.ui.IStartup;

public class MissingNatureDetector implements IStartup, IPropertyChangeListener {

	public static final String ENABLEMENT_PROPERTY = "org.eclipse.epp.mpc.naturelookup"; //$NON-NLS-1$

	private final JobGroup allJobs = new JobGroup(Messages.MissingNatureDetector_Title, 3, 0);

	private final Set<String> detectedNatures = new HashSet<String>();

	private final Set<LookupByNatureJob> lookupJobs = new HashSet<LookupByNatureJob>();

	private final IResourceChangeListener projectOpenListener = new IResourceChangeListener() {
		public void resourceChanged(IResourceChangeEvent event) {
			if (event.getDelta() == null) {
				return;
			}
			try {
				CollectMissingNaturesVisitor visitor = new CollectMissingNaturesVisitor();
				event.getDelta().accept(visitor);
				for (String natureId : visitor.getMissingNatures()) {
					triggerNatureLookup(natureId);
				}
				if (!visitor.getMissingNatures().isEmpty()) {
					showProposalsIfReady();
				}
			} catch (CoreException e) {
				MarketplaceClientUiPlugin.getInstance().getLog().log(
						new Status(IStatus.ERROR, MarketplaceClientUiPlugin.getInstance().getBundle().getSymbolicName(),
								e.getLocalizedMessage(), e));
			}
		}
	};

	private void triggerNatureLookup(final String natureId) {
		synchronized (lookupJobs) {
			if (detectedNatures.contains(natureId)) {
				return;
			} else {
				LookupByNatureJob mpcJob = new LookupByNatureJob(natureId);
				mpcJob.setSystem(false);
				mpcJob.setUser(false);
				mpcJob.setJobGroup(allJobs);
				mpcJob.addJobChangeListener(new JobChangeAdapter() {
					@Override
					public void done(IJobChangeEvent event) {
						showProposalsIfReady();
					}
				});
				lookupJobs.add(mpcJob);
				//schedule() needs to happen inside synchronized(...).
				//Otherwise it's not guaranteed that allJobs.getActiveJobs() will consider it,
				//and we might end up with processing unfinished jobs in showProposalsIfReady()
				mpcJob.schedule();
			}
		}
	}

	private void showProposalsIfReady() {
		Map<String, Collection<INode>> candidates;
		synchronized (lookupJobs) {
			if (!allJobs.getActiveJobs().isEmpty()) {
				return;
			}
			candidates = new HashMap<String, Collection<INode>>();
			for (LookupByNatureJob lookupJob : lookupJobs) {
				Collection<INode> entryCandidates = lookupJob.getCandidates();
				if (entryCandidates != null && !entryCandidates.isEmpty()) {
					candidates.put(lookupJob.getNatureId(), entryCandidates);
				}
			}
			lookupJobs.clear();
		}
		if (!candidates.isEmpty()) {
			new ShowNatureProposalsJob(candidates).schedule();
		}
	}

	public void earlyStartup() {
		IPreferenceStore preferenceStore = MarketplaceClientUiPlugin.getInstance().getPreferenceStore();
		preferenceStore.addPropertyChangeListener(this);
		boolean preferenceValue = preferenceStore.getBoolean(ENABLEMENT_PROPERTY);
		if (preferenceValue) {
			ResourcesPlugin.getWorkspace().addResourceChangeListener(projectOpenListener);
		}

	}

	public void propertyChange(PropertyChangeEvent event) {
		if (ENABLEMENT_PROPERTY.equals(event.getProperty())) {
			IWorkspace workspace = ResourcesPlugin.getWorkspace();
			if ((Boolean) event.getNewValue()) {
				workspace.addResourceChangeListener(this.projectOpenListener);
			} else {
				workspace.removeResourceChangeListener(this.projectOpenListener);
			}
		}
	}

}