/*******************************************************************************
 * Copyright (c) 2006-2012
 * Software Technology Group, Dresden University of Technology
 * DevBoost GmbH, Berlin, Amtsgericht Charlottenburg, HRB 140026
 * 
 * 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:
 *   Software Technology Group - TU Dresden, Germany;
 *   DevBoost GmbH - Berlin, Germany
 *      - initial API and implementation
 ******************************************************************************/
package org.reuseware.sokan.index.indexer;

import java.util.List;

import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.reuseware.sokan.ID;
import org.reuseware.sokan.IndexMetaData;
import org.reuseware.sokan.IndexRow;
import org.reuseware.sokan.index.util.ResourceUtil;
import org.reuseware.sokan.index.util.RowUtil;

/**
 * The meta data manager is responsible for creating index rows 
 * by calling indexers.
 */
public class MetaDataManager {
	private List<Indexer> indexers;

	/**
	 * Constructs a meta data manager for the given list of indexers.
	 * 
	 * @param indexers the indexers this meta data manager can call
	 */
	public MetaDataManager(List<Indexer> indexers) {
		this.indexers = indexers;
	}

	/**
	 * @param uri URI of the artifact to index
	 * @param generated true if the resource was generated by an indexer
	 * @param indexersToUse a subset of indexers to use in this indexing phase
	 * @param oldMetaData the previous index row of the artifact
	 * @param resourceSet the resource set to use
	 * @param monitor a monitor to record progress
	 * @return the created index row
	 */
	public IndexRow createIndexRow(URI uri, boolean generated, List<Indexer> indexersToUse,
			IndexMetaData oldMetaData, ResourceSet resourceSet, IProgressMonitor monitor) {
		if (uri == null || indexersToUse == null) {
			return null;
		}
		return build(uri, generated, indexersToUse, oldMetaData, resourceSet, monitor);
	}

	/**
	 * @param resource resource representing the artifact to index
	 * @param generated true if the resource was generated by an indexer
	 * @param indexersToUse a subset of indexers to use in this indexing phase
	 * @param oldMetaData the previous index row of the artifact
	 * @param resourceSet the resource set to use
	 * @param monitor a monitor to record progress
	 * @return the created index row
	 */
	public IndexRow createIndexRow(IResource resource, boolean generated,
			List<Indexer> indexersToUse, IndexMetaData oldMetaData,
			ResourceSet resourceSet, IProgressMonitor monitor) {
		URI physicalURI = ResourceUtil.uriFrom(resource);

		return build(physicalURI, generated, indexersToUse, oldMetaData, resourceSet, monitor);
	}

	private IndexRow build(URI physicalURI, boolean generated, List<Indexer> indexersToUse,
			IndexMetaData oldMetaData, ResourceSet resourceSet, IProgressMonitor monitor) {
		ID artifactID = ResourceUtil.idFrom(physicalURI);
		if (artifactID == null) {
			return null;
		}
		String idString = ResourceUtil.idString(artifactID);
		String uriString = ResourceUtil.uriString(physicalURI);

		IndexMetaData myData;
		if (oldMetaData != null) {
			myData = oldMetaData;
		} else {
			myData = RowUtil.buildMetaData();
		}
		invokeRegisteredIndexers(physicalURI, myData,
				indexersToUse, resourceSet, monitor);

		return RowUtil.buildIndexRow(idString, uriString, myData, generated);
	}

	private void invokeRegisteredIndexers(URI artifactURI, IndexMetaData data,
			List<Indexer> indexersToUse, ResourceSet resourceSet, IProgressMonitor monitor) {
		IndexMetaData metaData = RowUtil.buildMetaData();
		if (resourceSet == null) {
			return;
		}
		List<Indexer> myIndexers;
		if (indexersToUse == null) {
			myIndexers = indexers;
		} else {
			myIndexers = indexersToUse;
		}
		for (Indexer indexer : myIndexers) {
			String statusMessage = "Indexing " + artifactURI.toPlatformString(true) + " (" + indexer.getClass().getSimpleName() + ")";
			monitor.subTask(statusMessage);
			//System.out.println(statusMessage);
			indexer.createIndex(artifactURI, data, resourceSet);
			monitor.worked(1);

			if (data.isEmpty()) {
				continue;
			}
			metaData.putAll(data);
		}
	}
}