package org.eclipse.emf.henshin.sam.invcheck.algorithm;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import org.eclipse.emf.henshin.sam.invcheck.InvariantCheckerUtil;
import org.eclipse.emf.henshin.sam.invcheck.nac.PatternEdge;
import org.eclipse.emf.henshin.sam.invcheck.nac.PatternNode;
import org.eclipse.emf.henshin.sam.model.samannotation.AnnotatedElem;
import org.eclipse.emf.henshin.sam.model.samgraph.Edge;
import org.eclipse.emf.henshin.sam.model.samgraph.Graph;
import org.eclipse.emf.henshin.sam.model.samgraph.Node;
import org.eclipse.emf.henshin.sam.model.samrules.RuleGraph;
import org.eclipse.emf.henshin.sam.model.samrules.SamrulesFactory;
import org.eclipse.emf.henshin.sam.model.samtrace.Match;

/**
 * Merges two graphs and a graph matching to a merged graph. The typical inputs
 * are a forbidden subgraph, a part of the right side of a graph rule and their
 * matching.
 * 
 * The following diagram shows the behaviour of the merge method.
 * 
 * <p>
 * <img src="../../../../../doc/diagrams/graphMerger.png" alt="Graph merger">
 * </p>
 *
 */
public class GraphMerger implements AlgorithmComponent {

	private Map<Graph, Map<AnnotatedElem, AnnotatedElem>> refItems = new HashMap<Graph, Map<AnnotatedElem, AnnotatedElem>>();
	// private Map<Graph, Map<AnnotatedElem, AnnotatedElem>>
	// inverseSameInRuleProp = new HashMap<Graph, Map<AnnotatedElem,
	// AnnotatedElem>>();

	/**
	 * No comment provided by developer, please add a comment to improve
	 * documentation.
	 *
	 * @param forbiddenSubGraph
	 *            No description provided
	 * @param rule
	 *            No description provided
	 * @param matching
	 *            No description provided
	 * @return No description provided
	 */
	public RuleGraph merge(Graph forbiddenSubGraph, Graph rule, Match matching) {
		refItems.put(forbiddenSubGraph, new HashMap<AnnotatedElem, AnnotatedElem>());
		refItems.put(rule, new HashMap<AnnotatedElem, AnnotatedElem>());
		RuleGraph result = null;
		if (forbiddenSubGraph != null && rule != null && matching != null) {
			result = SamrulesFactory.eINSTANCE.createRuleGraph();// new Graph();
			result.setTypedOver(rule.getTypedOver());
			copyItems(forbiddenSubGraph, result, true);
			createAssocs(forbiddenSubGraph, result);
			/*
			 * this for loop ensures that items mentioned by the given matching,
			 * won't be copied twice.
			 */
			for (Iterator<Map.Entry<Node, Node>> iter = matching.getNodeMatching().iterator(); iter.hasNext();) {
				Map.Entry<Node, Node> tmpEntry = iter.next();
				Node ruleNode = tmpEntry.getKey();
				Node resultNode = (Node) refItems.get(forbiddenSubGraph).get(tmpEntry.getValue());
				assert resultNode != null;
				refItems.get(rule).put(ruleNode, resultNode);
				((PatternNode) resultNode).setSameInRule(ruleNode);
			}
			for (Iterator<Map.Entry<Edge, Edge>> iter = matching.getEdgeMatching().iterator(); iter.hasNext();) {
				Map.Entry<Edge, Edge> tmpEntry = iter.next();
				Edge ruleEdge = tmpEntry.getKey();
				Edge resultEdge = (Edge) refItems.get(forbiddenSubGraph).get(tmpEntry.getValue());
				assert resultEdge != null;
				refItems.get(rule).put(ruleEdge, resultEdge);
				((PatternEdge) resultEdge).setSameInRule(ruleEdge);
			}
			copyItems(rule, result, false);
			createAssocs(rule, result);
		}
		return result;
	}

	/**
	 * copies all graph items from srcGraph to resultGraph. thereby the
	 * qualified assocs for copies of elements are set.
	 *
	 * @param srcGraph
	 * @param resultGraph
	 */
	private void copyItems(Graph srcGraph, Graph resultGraph, boolean isForbidden) {
		for (Iterator<Node> iter = srcGraph.getNodes().iterator(); iter.hasNext();) {
			final Node srcNode = iter.next();
			if (!refItems.get(srcGraph).containsKey(srcNode)) {
				PatternNode resultNode = InvariantCheckerUtil.copyAsPattern(srcNode);

				resultGraph.getNodes().add(resultNode);
				refItems.get(srcGraph).put(srcNode, resultNode);
				if (isForbidden) {
					resultNode.setSameInProp(srcNode);
				} else {
					resultNode.setSameInRule(srcNode);
				}
			}
		}
		for (Iterator<Edge> iter = srcGraph.getEdges().iterator(); iter.hasNext();) {
			final Edge srcEdge = iter.next();
			if (!refItems.get(srcGraph).containsKey(srcEdge)) {
				PatternEdge resultEdge = InvariantCheckerUtil.copyAsPattern(srcEdge);
				resultGraph.getEdges().add(resultEdge);
				refItems.get(srcGraph).put(srcEdge, resultEdge);
				if (isForbidden) {
					resultEdge.setSameInProp(srcEdge);
				} else {
					resultEdge.setSameInRule(srcEdge);
				}
			}
		}
	}

	/**
	 * creates the assocs between the nodes and edges of srcGraph between the
	 * elements of resultGraph. to make this work, all elements have be copied
	 * first before calling this method
	 *
	 * @param srcGraph
	 *            the source Graph
	 * @param resultGraph
	 *            the resulting graph containing then the assoc from srcGraph
	 */
	private void createAssocs(Graph srcGraph, Graph resultGraph) {
		for (Iterator<Edge> iter = srcGraph.getEdges().iterator(); iter.hasNext();) {
			final Edge srcEdge = iter.next();
			Node srcTargetNode = srcEdge.getTarget();
			Node srcSourceNode = srcEdge.getSource();
			assert srcTargetNode != null : srcEdge + ": sourceNode equals null!";
			assert srcSourceNode != null : srcEdge + ": targetNode quals null!";

			Edge resultEdge = (Edge) refItems.get(srcGraph).get(srcEdge);
			Node resultTargetNode = (Node) refItems.get(srcGraph).get(srcTargetNode);
			Node resultSourceNode = (Node) refItems.get(srcGraph).get(srcSourceNode);

			resultEdge.setSource(resultSourceNode);
			resultEdge.setTarget(resultTargetNode);
		}
	}

	public void reset() {
		refItems = new HashMap<Graph, Map<AnnotatedElem, AnnotatedElem>>();
	}

}

/*
 * $Log$ Revision 1.4 2007/06/25 17:48:20 basilb fixed a lot of these bugs
 * testing does not find but evaluating ;)
 *
 * Revision 1.3 2007/01/11 14:44:23 basilb even more usage of generics
 *
 * Revision 1.2 2007/01/03 09:27:48 basilb removed compile errors caused by
 * wrong import declarations; introduced empty plugin class to ensure correct
 * loading
 *
 */