/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2002-2008, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.filter;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import javax.xml.namespace.QName;

import org.geotools.factory.CommonFactoryFinder;
import org.geotools.feature.NameImpl;
import org.geotools.filter.v1_1.OGC;
import org.geotools.xml.Node;
import org.opengis.feature.type.Name;
import org.opengis.filter.BinaryComparisonOperator;
import org.opengis.filter.BinaryLogicOperator;
import org.opengis.filter.Filter;
import org.opengis.filter.Id;
import org.opengis.filter.PropertyIsBetween;
import org.opengis.filter.PropertyIsLike;
import org.opengis.filter.PropertyIsNull;
import org.opengis.filter.expression.Expression;
import org.opengis.filter.expression.Function;
import org.opengis.filter.identity.Identifier;
import org.opengis.filter.spatial.BinarySpatialOperator;

/**
 * Convenience class for filter parsing. 
 * <p>
 * The primary function of this class is to share code among the different versions 
 * of filter parsing.
 * </p>
 * @author Justin Deoliveira, OpenGEO
 *
 *
 *
 *
 * @source $URL$
 */
public class FilterParsingUtils {

    public static Object Filter_getProperty(Object object, QName qName ) {
        Filter filter = (Filter) object;

        //use the local name to handle oth the OGC and FES namespaces
        String name = qName.getLocalPart();
        
        //<xsd:element ref="ogc:spatialOps"/>
        if ("spatialOps".equals(name) && filter instanceof BinarySpatialOperator) {
            return filter;
        }

        //<xsd:element ref="ogc:comparisonOps"/>
        if ("comparisonOps".equals(name)) {
            //JD: extra check here because many of our spatial implementations
            // extend both      
            if ( filter instanceof BinaryComparisonOperator
                && !(filter instanceof BinarySpatialOperator)) {
                return filter;    
            }
            else {
                //filters that don't extend BinaryComparisonOperator but are still 
                // comparisonOps
                if ( filter instanceof PropertyIsLike || filter instanceof PropertyIsNull 
                    || filter instanceof PropertyIsBetween ) {
                    return filter;
                }
            }
        }

        //<xsd:element ref="ogc:logicOps"/>
        if ("logicOps".equals(name) && filter instanceof BinaryLogicOperator) {
            return filter;
        }

        //<xsd:element maxOccurs="unbounded" ref="ogc:_Id"/>
        if ( filter instanceof Id && 
            ( "_Id".equals(name) /*1.1/2.0*/ || "FeatureId".equals(name) /*1.0*/ ) ) {
            //unwrap
            Id id = (Id) filter;

            return id.getIdentifiers();
        }

        return null;
    }

    public static List<Filter> BinaryLogicOperator_getChildFilters( Node node, org.opengis.filter.FilterFactory factory ) {
        List<Filter> filters = node.getChildValues(Filter.class);
        if ( filters.size() < 2 ) {
            //look for Id elements and turn them into fid filters
            //note: this is not spec compliant and is a bit lax
            List<Identifier> ids = node.getChildValues( Identifier.class );
            for ( Identifier id : ids ) {
                filters.add( factory.id( Collections.singleton( id ) ) ) ;
            }
            
            //look for extended operator(s)
            filters.addAll(parseExtendedOperators(node, factory));
        }

        //TODO: this parsing returns teh children out of order... 
        return filters;
    }
    
    public static List<Filter> parseExtendedOperators(Node node, org.opengis.filter.FilterFactory factory) {
        List<Filter> extOps = new ArrayList();
        
        //TODO: this doesn't actually handle the case of an extended operator that does not take
        // any arguments
        if (node.hasChild(Expression.class)) {
            //case of a single operator containing a single expression
            Node n = node.getChild(Expression.class);
            Name opName = new NameImpl(n.getComponent().getNamespace(), n.getComponent().getName());
            
            Filter extOp = lookupExtendedOperator(opName, Arrays.asList((Expression) n.getValue()), factory);
            if (extOp != null) {
                extOps.add(extOp);
            }
        }
        else if (node.hasChild(Map.class)) {
            List<Node> children = node.getChildren(Map.class);
            for (Node n : children) {
                Name opName = new NameImpl(n.getComponent().getNamespace(), n.getComponent().getName());
                Map map = (Map) n.getValue();
                
                List<Expression> expressions = new ArrayList();
                for (Object o : map.values()) {
                    if (o instanceof Expression) {
                        expressions.add((Expression) o);
                    }
                }

                Filter extOp = lookupExtendedOperator(opName, expressions, factory);
                if (extOp != null) {
                    extOps.add(extOp);
                }
            }
        }

        return extOps;
    }

    static Filter lookupExtendedOperator(Name opName, List<Expression> expressions, 
        org.opengis.filter.FilterFactory factory) {
        FunctionFinder finder = new FunctionFinder(null);
        Function f = finder.findFunction(opName.getLocalPart(), expressions);
        return factory.equal(f, factory.literal(true), true);
    }
}