package org.simantics.document.ui.graphfile;

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.WriteGraph;
import org.simantics.db.common.utils.NameUtils;
import org.simantics.db.exception.DatabaseException;
import org.simantics.document.DocumentResource;
import org.simantics.layer0.Layer0;
/**
 * Util class for managing document versions
 * 
 * Document version history mode  is searched with relations:
 * 1. l0.PartOf
 * 2. l0.IsOwnedBy
 * 3. l0.IsDependencyOf 
 * 
 * If library is not found, history mode is assumed to be flat.
 * 
 * In order to have working tree history, the library must contain proper configuration for relations:
 *  doc.HasLibraryRelation
 *  doc.HasVersionType
 *  
 * @author Marko Luukkainen <marko.luukkainen@vtt.fi>
 *
 */
public class DocumentVersionUtils {

	public enum VersionMode{FLAT,TREE};
	
	
	/**
	 * Adds a new document version.
	 * 
	 * Expects that newDocument is not part of document version chain, and oldDocument does not have newer version.
	 * 
	 * @param graph
	 * @param oldDocument
	 * @param newDocument
	 * @param relation
	 * @throws DatabaseException
	 */
	public static void createNewVersion(WriteGraph graph, Resource oldDocument, Resource newDocument, Resource relation) throws DatabaseException{
		DocumentResource doc = DocumentResource.getInstance(graph);
		if (graph.hasStatement(oldDocument, doc.HasNewerVersion))
			throw new DatabaseException("Document " + NameUtils.getSafeName(graph, oldDocument) +" has already new version"); //$NON-NLS-1$ //$NON-NLS-2$
		
		Resource inverse = graph.getInverse(relation);
		Resource lib = graph.getSingleObject(oldDocument, inverse);
		String modeString = graph.getPossibleRelatedValue(lib, doc.HasVersionType);
		VersionMode mode = VersionMode.FLAT;
		if (modeString != null)
			mode = VersionMode.valueOf(modeString);
		
		graph.claim(oldDocument, doc.HasNewerVersion, newDocument);
		graph.claim(lib, relation, newDocument);
		
		if (mode == VersionMode.TREE) {
			graph.deny(lib,relation,oldDocument);
			graph.claim(newDocument,relation,oldDocument);
		}
		FileDocumentUtil.createUniqueName(graph, newDocument);
	}
	
	/**
	 * Sets document version relationship between two documents. 
	 * 
	 * If the documents are already part of the same version chain this method does nothing.
	 * 
	 * If documents are already set to some version chain with given relation, this method replaces the exiting links.
	 * 
	 * @param graph
	 * @param document1
	 * @param document2
	 * @param versionRel
	 * @throws DatabaseException
	 */
	public static void setVersion(WriteGraph graph, Resource document1, Resource document2, Resource versionRel) throws DatabaseException {
		DocumentResource doc = DocumentResource.getInstance(graph);
		// document type must match
		if (!graph.getSingleType(document2, doc.Document).equals(graph.getSingleType(document1, doc.Document)))
			return;
		if (!versionRel.equals(doc.HasNewerVersion) && !(versionRel.equals(doc.HasOlderVersion)))
			throw new IllegalArgumentException("Unknow version relation + " + graph.getPossibleURI(versionRel)); //$NON-NLS-1$
		
		Resource versionRelInv = graph.getInverse(versionRel);
		// toSet must not be part of the document's version history
		Resource r = document1;
		while (r != null) {
			if (r.equals(document2))
				return;
			r = graph.getPossibleObject(r, versionRel);
		}
		
		r = document2;
		while (r != null) {
			if (r.equals(document1))
				return;
			r = graph.getPossibleObject(r, versionRel);
		}
		// At the moment document revision history is linear (no branching).
		Resource document1Ver = graph.getPossibleObject(document1, versionRel);
		if (document1Ver != null)
			unsetVersion(graph, document1, document1Ver, versionRel);
		Resource document2Ver = graph.getPossibleObject(document2, versionRelInv);
		if (document2Ver != null)
			unsetVersion(graph, document2, document2Ver, versionRelInv);
		
		graph.claim(document1, versionRel, document2);
		
		Resource lib = getLib(graph, document1);
		if (lib != null) {
			Resource relation = graph.getPossibleObject(lib, doc.HasLibraryRelation);
			String type= graph.getPossibleRelatedValue(lib, doc.HasVersionType);
			if ("TREE".equals(type) && relation != null) { //$NON-NLS-1$
				if (versionRel.equals(doc.HasOlderVersion)) {
					graph.deny(document2, graph.getInverse(relation));
					graph.claim(document1,relation,document2);
				} else {
					graph.deny(document1, graph.getInverse(relation));
					graph.claim(document2,relation,document1);
				}
			}
			
		}
	}
	
	/**
	 * Unlinks document version relationship between two documents. 
	 * @param graph
	 * @param document1
	 * @param document2
	 * @param versionRel
	 * @throws DatabaseException
	 */
	public static void unsetVersion(WriteGraph graph, Resource document1, Resource document2, Resource versionRel) throws DatabaseException {
		DocumentResource doc = DocumentResource.getInstance(graph);
		if (!versionRel.equals(doc.HasNewerVersion) && !(versionRel.equals(doc.HasOlderVersion)))
			throw new IllegalArgumentException("Unknow version relation + " + graph.getPossibleURI(versionRel)); //$NON-NLS-1$
		
		graph.deny(document1, versionRel,document2);
		Resource lib = getLib(graph, document1);
		if (lib != null) {
			Resource relation = graph.getPossibleObject(lib, doc.HasLibraryRelation);
			String type= graph.getPossibleRelatedValue(lib, doc.HasVersionType);
			if ("TREE".equals(type) && relation != null) { //$NON-NLS-1$
				if (versionRel.equals(doc.HasOlderVersion)) {
					graph.deny(document1, relation);
					graph.claim(lib,relation,document2);
					FileDocumentUtil.createUniqueName(graph, document2);
				} else {
					graph.deny(document1, graph.getInverse(relation));
					graph.claim(lib,relation,document1);
					FileDocumentUtil.createUniqueName(graph, document1);
				}
			}
			
		}
	}
	
	private static Resource getLib(ReadGraph graph, Resource document) throws DatabaseException {
		Layer0 l0 = Layer0.getInstance(graph);
		DocumentResource doc = DocumentResource.getInstance(graph);
		Resource r = document;
		while (true) {
			Resource lib = graph.getPossibleObject(r, l0.PartOf);
			if (lib == null)
				lib = graph.getPossibleObject(r, l0.IsOwnedBy);
			if (lib == null)
				lib =  graph.getPossibleObject(r, l0.IsDependencyOf);
			if (lib == null)
				return null;
			if (!graph.isInstanceOf(lib, doc.Document))
				return lib;
			r = lib;
		}
	}
}