/*******************************************************************************
 * Copyright (c) 2007, 2010 BMW Car IT, Technische Universitaet Muenchen, 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:
 * BMW Car IT - Initial API and implementation
 * Technische Universitaet Muenchen - Major refactoring and extension
 *******************************************************************************/
package org.eclipse.emf.edapt.history.reconstruction;

import java.util.Collection;
import java.util.List;
import java.util.Map.Entry;

import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EPackage;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.emf.edapt.internal.common.MetamodelExtent;
import org.eclipse.emf.edapt.spi.history.Change;
import org.eclipse.emf.edapt.spi.history.CompositeChange;
import org.eclipse.emf.edapt.spi.history.History;
import org.eclipse.emf.edapt.spi.history.InitializerChange;
import org.eclipse.emf.edapt.spi.history.MigrateableChange;
import org.eclipse.emf.edapt.spi.history.MigrationChange;
import org.eclipse.emf.edapt.spi.history.PrimitiveChange;
import org.eclipse.emf.edapt.spi.history.Release;
import org.eclipse.emf.edapt.spi.history.ValueChange;

/**
 * Reconstructor visiting the history in backward direction
 *
 * @author herrmama
 * @author $Author$
 * @version $Rev$
 * @levd.rating RED Rev:
 */
public class BackwardReconstructorBase extends CompositeReconstructorBase {

	/**
	 * Target history element
	 */
	private EObject target;

	/**
	 * Whether reconstruction ends before or after target history element
	 */
	private boolean before;

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected void doReconstruct(EObject target, History originalHistory, boolean before) {

		init(originalHistory);
		init(mapping, extent);

		this.target = target;
		this.before = before;

		endHistory(originalHistory);

		try {
			final List<Release> releases = originalHistory.getReleases();
			for (int i = releases.size() - 1; i >= 0; i--) {
				final Release release = releases.get(i);
				doReconstruct(release);
			}
		} catch (final FinishedException e) {
			// reconstruction is finished
		}

		startHistory(originalHistory);
	}

	/**
	 * Initialize mapping and extent from the history
	 */
	private void init(History originalHistory) {
		mapping = new Mapping();
		final EcoreUtil.Copier copier = new EcoreUtil.Copier();
		final Collection<EPackage> rootPackages = copier.copyAll(originalHistory.getRootPackages());
		copier.copyReferences();
		for (final Entry<EObject, EObject> entry : copier.entrySet()) {
			mapping.map(entry.getKey(), entry.getValue());
		}
		extent = new MetamodelExtent(rootPackages);
	}

	/**
	 * Perform reconstruction of a release
	 */
	private void doReconstruct(Release originalRelease) {

		if (!before && originalRelease == target) {
			throw new FinishedException();
		}

		endRelease(originalRelease);

		final List<Change> changes = originalRelease.getChanges();
		for (int i = changes.size() - 1; i >= 0; i--) {
			final Change change = changes.get(i);
			doReconstruct(change);
		}

		startRelease(originalRelease);

		if (before && originalRelease == target) {
			throw new FinishedException();
		}
	}

	/**
	 * Perform reconstruction of a change
	 */
	private void doReconstruct(Change originalChange) {

		if (!before && originalChange == target) {
			throw new FinishedException();
		}

		endChange(originalChange);

		if (originalChange instanceof CompositeChange) {
			final CompositeChange compositeChange = (CompositeChange) originalChange;
			final List<PrimitiveChange> changes = compositeChange.getChanges();
			for (int i = changes.size() - 1; i >= 0; i--) {
				final Change change = changes.get(i);
				doReconstruct(change);
			}
		}
		else if (originalChange instanceof MigrationChange) {
			final MigrationChange migrationChange = (MigrationChange) originalChange;
			final List<MigrateableChange> changes = migrationChange.getChanges();
			for (int i = changes.size() - 1; i >= 0; i--) {
				final Change change = changes.get(i);
				doReconstruct(change);
			}
		}
		else if (originalChange instanceof InitializerChange) {
			final InitializerChange create = (InitializerChange) originalChange;
			final List<ValueChange> changes = create.getChanges();
			for (int i = changes.size() - 1; i >= 0; i--) {
				final ValueChange change = changes.get(i);
				doReconstruct(change);
			}
		}

		startChange(originalChange);

		if (before && originalChange == target) {
			throw new FinishedException();
		}
	}
}