/**
 *        CloudGraph Community Edition (CE) License
 * 
 * This is a community release of CloudGraph, a dual-license suite of
 * Service Data Object (SDO) 2.1 services designed for relational and 
 * big-table style "cloud" databases, such as HBase and others. 
 * This particular copy of the software is released under the 
 * version 2 of the GNU General Public License. CloudGraph was developed by 
 * TerraMeta Software, Inc.
 * 
 * Copyright (c) 2013, TerraMeta Software, Inc. All rights reserved.
 * 
 * General License information can be found below.
 * 
 * This distribution may include materials developed by third
 * parties. For license and attribution notices for these
 * materials, please refer to the documentation that accompanies
 * this distribution (see the "Licenses for Third-Party Components"
 * appendix) or view the online documentation at 
 * <http://cloudgraph.org/licenses/>. 
 */
package org.cloudgraph.hbase.scan;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.cloudgraph.config.DataGraphConfig;
import org.cloudgraph.config.UserDefinedRowKeyFieldConfig;
import org.cloudgraph.hbase.graph.EdgeRecognizerContext;
import org.cloudgraph.query.expr.DefaultRelationalBinaryExpr;
import org.cloudgraph.query.expr.EvaluationContext;
import org.cloudgraph.query.expr.RelationalBinaryExpr;
import org.plasma.query.model.Literal;
import org.plasma.query.model.Property;
import org.plasma.query.model.RelationalOperator;
import org.plasma.sdo.PlasmaProperty;
import org.plasma.sdo.PlasmaType;

/**
 * An {@link RelationalBinaryExpr} implementation which uses a specific 
 * evaluation {@link ScanRecognizerContext context} to evaluate
 * the value(s) of a data graph property along the query property
 * traversal path within the context of a binary expression (syntax) tree.       
 * 
 * 
 * @author Scott Cinnamond
 * @since 0.5.3
 * @see ScanRecognizerContext
 */
public class ScanRecognizerRelationalBinaryExpr extends DefaultRelationalBinaryExpr 
    implements RelationalBinaryExpr {
    private static Log log = LogFactory.getLog(ScanRecognizerRelationalBinaryExpr.class);
 	protected ScanLiteral scanLiteral;
	
    /**
     * Constructs an expression based on the given terms. 
     * @param property the "left" property term
     * @param literal the "right" literal term
     * @param operator the relational operator
     * @see EdgeRecognizerContext
     */
    public ScanRecognizerRelationalBinaryExpr(Property property,
			Literal literal, 
			RelationalOperator operator) {
		super(property, literal, operator);
	}
	
	/**
	 * Returns a "truth" value for the expression using a specific 
     * evaluation {@link ScanRecognizerContext context} by
     * ...
     * within the binary expression tree.       
	 * @param context
	 * @return a "truth" value for the expression
     * @see ScanRecognizerContext
	 */
	@Override
	public boolean evaluate(EvaluationContext context) {
		ScanRecognizerContext ctx = (ScanRecognizerContext)context;		
		ScanLiteral literal = createLiteral(ctx.getGraph());				
		
		return false;
	}
	
	private ScanLiteral createLiteral(DataGraphConfig graph) {
		// Match the current property to a user defined 
		// row key token, if found we can process
		UserDefinedRowKeyFieldConfig fieldConfig = graph.getUserDefinedRowKeyField(this.propertyPath);
		if (fieldConfig != null) 
		{
			PlasmaProperty property = (PlasmaProperty)fieldConfig.getEndpointProperty();
			ScanLiteralFactory factory = new ScanLiteralFactory();
			
			ScanLiteral scanLiteral = factory.createLiteral(
				this.literal.getValue(), property, 
				(PlasmaType)graph.getRootType(), 
				this.operator, 
				fieldConfig);
			return scanLiteral;
		}
		else
	        log.warn("no user defined row-key field for query path '"
			    	+ this.propertyPath + "' - deferring to graph recogniser post processor");
	
	    return null;
	}
	
}