package org.drools.compiler.xml.rules;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.HashSet;

import org.drools.lang.descr.FieldConstraintDescr;
import org.drools.lang.descr.LiteralRestrictionDescr;
import org.drools.lang.descr.QualifiedIdentifierRestrictionDescr;
import org.drools.lang.descr.RestrictionConnectiveDescr;
import org.drools.lang.descr.ReturnValueRestrictionDescr;
import org.drools.lang.descr.VariableRestrictionDescr;
import org.drools.xml.BaseAbstractHandler;
import org.drools.xml.ExtensibleXmlParser;
import org.drools.xml.Handler;
import org.w3c.dom.Element;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

/**
 * @author mproctor
 * @author fmeyer
 * 
 */
public class LiteralRestrictionHandler extends BaseAbstractHandler
    implements
    Handler {
    public LiteralRestrictionHandler() {
        if ( (this.validParents == null) && (this.validPeers == null) ) {
            this.validParents = new HashSet();
            this.validParents.add( FieldConstraintDescr.class );
            this.validParents.add( RestrictionConnectiveDescr.class );

            this.validPeers = new HashSet();
            this.validPeers.add( null );

            this.validPeers.add( LiteralRestrictionDescr.class );
            this.validPeers.add( ReturnValueRestrictionDescr.class );
            this.validPeers.add( VariableRestrictionDescr.class );
            this.validPeers.add( RestrictionConnectiveDescr.class );
            this.validPeers.add( QualifiedIdentifierRestrictionDescr.class );

            this.allowNesting = false;
        }
    }

    public Object start(final String uri,
                        final String localName,
                        final Attributes attrs,
                        final ExtensibleXmlParser parser) throws SAXException {
        parser.startElementBuilder( localName,
                                    attrs );

        final String evaluator = attrs.getValue( "evaluator" );
        emptyAttributeCheck( localName, "evaluator", evaluator, parser );

        final String text = attrs.getValue( "value" );

        final LiteralRestrictionDescr literalDescr = new LiteralRestrictionDescr( evaluator,
                                                                                  text );

        return literalDescr;
    }

    public Object end(final String uri,
                      final String localName,
                      final ExtensibleXmlParser parser) throws SAXException {
        final Element element = parser.endElementBuilder();

        final LiteralRestrictionDescr literalDescr = (LiteralRestrictionDescr) parser.getCurrent();

        final Object parent = parser.getParent();

        if ( parent instanceof FieldConstraintDescr ) {
            final FieldConstraintDescr fieldConstriantDescr = (FieldConstraintDescr) parent;
            fieldConstriantDescr.addRestriction( literalDescr );
        } else if ( parent instanceof RestrictionConnectiveDescr ) {
            final RestrictionConnectiveDescr restrictionDescr = (RestrictionConnectiveDescr) parent;
            restrictionDescr.addRestriction( literalDescr );
        }
        return literalDescr;
    }

    public Class generateNodeFor() {
        return LiteralRestrictionDescr.class;
    }
}