/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

package org.apache.jena.riot.process.inf;

import java.util.List ;

import org.apache.jena.graph.Node ;
import org.apache.jena.vocabulary.RDF ;


/** Apply a fixed set of inference rules to a stream of triples.
 *  This is inference on the A-Box (the data) with respect to a fixed T-Box
 *  (the vocabulary, ontology).
 *  <ul>
 *  <li>rdfs:subClassOf (transitive)</li>
 *  <li>rdfs:subPropertyOf (transitive)</li>
 *  <li>rdfs:domain</li>
 *  <li>rdfs:range</li>
 *  </ul>
 *  
 *  Usage: call process(Node, Node, Node), outputs to derive(Node, Node, Node).
 */

abstract class InferenceProcessorRDFS
{
    // Calculates hierarchies (subclass, subproperty) from a model.
    // Assumes that model has no metavocabulary (use an inferencer on the model first if necessary).
    
    // Todo:
    //   rdfs:member
    //   list:member ???
    
    // Todo:
    //   rdfs:member
    //   list:member ???
    
    // Work in NodeID space?  But Node id caching solves most of the problems.
    
    // Expanded hierarchy:
    // If C < C1 < C2 then C2 is in the list for C 

    
    static final Node rdfType = RDF.type.asNode() ;
    private final InferenceSetupRDFS state ;
    
    public InferenceProcessorRDFS(InferenceSetupRDFS state)
    {
        this.state = state ;
    }

    public void process(Node s, Node p, Node o)
    {
        subClass(s,p,o) ;
        subProperty(s,p,o) ;

        // domain() and range() also go through subClass processing. 
        domain(s,p,o) ;
        range(s,p,o) ;
    }

    public abstract void derive(Node s, Node p, Node o) ;

    /*
     * [rdfs8:  (?a rdfs:subClassOf ?b), (?b rdfs:subClassOf ?c) -> (?a rdfs:subClassOf ?c)] 
     * [rdfs9:  (?x rdfs:subClassOf ?y), (?a rdf:type ?x) -> (?a rdf:type ?y)] 
     */
    final private void subClass(Node s, Node p, Node o)
    {
        if ( p.equals(rdfType) )
        {
            List<Node> x = state.transClasses.get(o) ;
            if ( x != null )
                for ( Node c : x )
                    derive(s,p,c) ;
        }
    }

    // Rule extracts from Jena's RDFS rules etc/rdfs.rules 
    
    /*
     * [rdfs5a: (?a rdfs:subPropertyOf ?b), (?b rdfs:subPropertyOf ?c) -> (?a rdfs:subPropertyOf ?c)] 
     * [rdfs6:  (?a ?p ?b), (?p rdfs:subPropertyOf ?q) -> (?a ?q ?b)] 
     */
    private void subProperty(Node s, Node p, Node o)
    {
        List<Node> x = state.transProperties.get(p) ;
        if ( x != null )
        {
            for ( Node p2 : x )
                derive(s, p2, o) ;
        }
    }

    /*
     * [rdfs2:  (?p rdfs:domain ?c) -> [(?x rdf:type ?c) <- (?x ?p ?y)] ]
     * [rdfs9:  (?x rdfs:subClassOf ?y), (?a rdf:type ?x) -> (?a rdf:type ?y)]  
     */
    final private void domain(Node s, Node p, Node o)
    {
        List<Node> x = state.domainList.get(p) ;
        if ( x != null )
        {
            for ( Node c : x )
            {
                derive(s, rdfType, c) ;
                subClass(s, rdfType, c) ;
            }
        }
    }

    /*
     * [rdfs3:  (?p rdfs:range ?c)  -> [(?y rdf:type ?c) <- (?x ?p ?y)] ]
     * [rdfs9:  (?x rdfs:subClassOf ?y), (?a rdf:type ?x) -> (?a rdf:type ?y)]  
     */ 
    final private void range(Node s, Node p, Node o)
    {
        // Mask out literal subjects
        if ( o.isLiteral() )
            return ;
        // Range
        List<Node> x = state.rangeList.get(p) ;
        if ( x != null )
        {
            for ( Node c : x )
            {
                derive(o, rdfType, c) ;
                subClass(o, rdfType, c) ;
            }
        }
    }
}