package org.simantics.interop.test;

import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;

/**
 * 
 * @author Marko Luukkainen <marko.luukkainen@vtt.fi>
 *
 */
public abstract class ResourceComparator {
	
	public static int NO_MATCH = Integer.MAX_VALUE;   // Comparison result when Resources cannot match.
	public static int UNDECISIVE = 0;                 // Comparison result when current available data is not enough to decide if the Resources match or not. 
	public static int EXACT_MATCH = 1;                // Comparison result when Resources are exact match.
	
	private GraphComparator comparator;
	
	void setComparator(GraphComparator comparator) {
		this.comparator = comparator;
	}
	
	public GraphComparator getComparator() {
		return comparator;
	}
	
	/**
	 * Optional initialization method for overriding implementations.
	 * 
	 * @param g
     * @param r1 root 1
     * @param r2 root 2
	 */
	public void initialize(ReadGraph g, Resource r1, Resource r2) throws DatabaseException {
	    
	}
	
	/**
	 * Compares two resources and returns numeric value of differences, minimum value is 1. 
	 * 
	 * Special values:
	 * Integer.MAX_VALUE: Objects are not comparable.
	 * 0 (zero): Object comparison is not reliable. 
	 * 
	 * Result is same as compare(g, o1, o2, true);
	 * 
	 */
	public abstract int compare(ReadGraph g, Resource o1, Resource o2) throws DatabaseException;
	
	/**
	 * Compares two resources and returns numeric value of differences, minimum value is 1. 
	 * 
	 * Special values:
	 * Integer.MAX_VALUE: Objects are not comparable.
	 * 0 (zero): Object comparison is not reliable. 
	 * 
	 * @param g
	 * @param o1
	 * @param o2
	 * @param local: if true, comparison must not utilise information stored into comparator. 
	 * @return
	 * @throws DatabaseException
	 */
	public abstract int compare(ReadGraph g, Resource o1, Resource o2, boolean local) throws DatabaseException;

}