/*******************************************************************************
 * Copyright (c) 2004, 2015 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 - Initial API and implementation
 *     James Blackburn (Broadcom Corp.) - ongoing development
 *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 473427
 *******************************************************************************/
package org.eclipse.core.internal.resources;

import java.util.*;
import org.eclipse.core.internal.events.ILifecycleListener;
import org.eclipse.core.internal.events.LifecycleEvent;
import org.eclipse.core.resources.*;
import org.eclipse.core.resources.team.ResourceRuleFactory;
import org.eclipse.core.resources.team.TeamHook;
import org.eclipse.core.runtime.jobs.ISchedulingRule;
import org.eclipse.core.runtime.jobs.MultiRule;

/**
 * Class for calculating scheduling rules for resource changing operations.
 * This factory delegates to the TeamHook to obtain an appropriate factory
 * for the resource that the operation is proposing to modify.
 */
class Rules implements IResourceRuleFactory, ILifecycleListener {
	private final ResourceRuleFactory defaultFactory = new ResourceRuleFactory() {/**/};
	/**
	 * Map of project names to the factory for that project.
	 */
	private final Map<String, IResourceRuleFactory> projectsToRules = Collections.synchronizedMap(new HashMap<String, IResourceRuleFactory>());
	private final TeamHook teamHook;
	private final IWorkspaceRoot root;

	/**
	 * Creates a new scheduling rule factory for the given workspace
	 * @param workspace
	 */
	Rules(Workspace workspace) {
		this.root = workspace.getRoot();
		this.teamHook = workspace.getTeamHook();
		workspace.addLifecycleListener(this);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a build operation.
	 */
	@Override
	public ISchedulingRule buildRule() {
		//team hook currently cannot change this rule
		return root;
	}

	/**
	 * Obtains the scheduling rule from the appropriate factories for a copy operation.
	 */
	@Override
	public ISchedulingRule copyRule(IResource source, IResource destination) {
		if (source.getType() == IResource.ROOT || destination.getType() == IResource.ROOT)
			return root;
		//source is not modified, destination is created
		return factoryFor(destination).copyRule(source, destination);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a create operation.
	 */
	@Override
	public ISchedulingRule createRule(IResource resource) {
		if (resource.getType() == IResource.ROOT)
			return root;
		return factoryFor(resource).createRule(resource);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a delete operation.
	 */
	@Override
	public ISchedulingRule deleteRule(IResource resource) {
		if (resource.getType() == IResource.ROOT)
			return root;
		return factoryFor(resource).deleteRule(resource);
	}

	/**
	 * Returns the scheduling rule factory for the given resource
	 */
	private IResourceRuleFactory factoryFor(IResource destination) {
		IResourceRuleFactory fac = projectsToRules.get(destination.getFullPath().segment(0));
		if (fac == null) {
			//use the default factory if the project is not yet accessible
			if (!destination.getProject().isAccessible())
				return defaultFactory;
			//ask the team hook to supply one
			fac = teamHook.getRuleFactory(destination.getProject());
			projectsToRules.put(destination.getFullPath().segment(0), fac);
		}
		return fac;
	}

	@Override
	public void handleEvent(LifecycleEvent event) {
		//clear resource rule factory for projects that are about to be closed
		//or deleted. It is ok to do this during a PRE event because the rule
		//has already been obtained at this point.
		switch (event.kind) {
			case LifecycleEvent.PRE_PROJECT_CLOSE :
			case LifecycleEvent.PRE_PROJECT_DELETE :
			case LifecycleEvent.PRE_PROJECT_MOVE :
				setRuleFactory((IProject) event.resource, null);
		}
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a charset change operation.
	 */
	@Override
	public ISchedulingRule charsetRule(IResource resource) {
		if (resource.getType() == IResource.ROOT)
			return null;
		return factoryFor(resource).charsetRule(resource);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a derived flag change operation.
	 */
	@Override
	public ISchedulingRule derivedRule(IResource resource) {
		//team hook currently cannot change this rule
		return null;
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a marker change operation.
	 */
	@Override
	public ISchedulingRule markerRule(IResource resource) {
		//team hook currently cannot change this rule
		return null;
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a modify operation.
	 */
	@Override
	public ISchedulingRule modifyRule(IResource resource) {
		if (resource.getType() == IResource.ROOT)
			return root;
		return factoryFor(resource).modifyRule(resource);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factories for a move operation.
	 */
	@Override
	public ISchedulingRule moveRule(IResource source, IResource destination) {
		if (source.getType() == IResource.ROOT || destination.getType() == IResource.ROOT)
			return root;
		//treat a move across projects as a create on the destination and a delete on the source
		if (!source.getFullPath().segment(0).equals(destination.getFullPath().segment(0)))
			return MultiRule.combine(modifyRule(source.getProject()), modifyRule(destination.getProject()));
		return factoryFor(source).moveRule(source, destination);
	}

	/**
	 * Obtains the scheduling rule from the appropriate factory for a refresh operation.
	 */
	@Override
	public ISchedulingRule refreshRule(IResource resource) {
		if (resource.getType() == IResource.ROOT)
			return root;
		return factoryFor(resource).refreshRule(resource);
	}

	/* (non-javadoc)
	 * Implements TeamHook#setRuleFactory
	 */
	void setRuleFactory(IProject project, IResourceRuleFactory factory) {
		if (factory == null)
			projectsToRules.remove(project.getName());
		else
			projectsToRules.put(project.getName(), factory);
	}

	/**
	 * Combines rules for each parameter to validateEdit from the corresponding
	 * rule factories.
	 */
	@Override
	public ISchedulingRule validateEditRule(IResource[] resources) {
		if (resources.length == 0)
			return null;
		//optimize rule for single file
		if (resources.length == 1) {
			if (resources[0].getType() == IResource.ROOT)
				return root;
			return factoryFor(resources[0]).validateEditRule(resources);
		}
		//gather rules for each resource from appropriate factory
		HashSet<ISchedulingRule> rules = new HashSet<>();
		IResource[] oneResource = new IResource[1];
		for (IResource resource : resources) {
			if (resource.getType() == IResource.ROOT)
				return root;
			oneResource[0] = resource;
			ISchedulingRule rule = factoryFor(resource).validateEditRule(oneResource);
			if (rule != null)
				rules.add(rule);
		}
		if (rules.isEmpty())
			return null;
		if (rules.size() == 1)
			return rules.iterator().next();
		ISchedulingRule[] ruleArray = rules.toArray(new ISchedulingRule[rules.size()]);
		return new MultiRule(ruleArray);
	}
}