/*
 * 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.sparql.core;

import java.util.Iterator ;

import org.apache.jena.atlas.lib.Sync ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.Node ;
import org.apache.jena.query.ReadWrite ;
import org.apache.jena.shared.Lock ;
import org.apache.jena.sparql.SystemARQ ;
import org.apache.jena.sparql.util.Context ;

public class DatasetGraphWrapper implements DatasetGraph, Sync 
{
    // The wrapped DatasetGraph but all calls go via get() so this can be null.
    private final DatasetGraph dsg ;
    
    /** Return the DatasetGraph being wrapped. */
    public final DatasetGraph getWrapped() { 
        return get() ;
    }
    
    /** Recursively unwrap a DatasetGraphWrapped.
     * 
     * @return the first found {@link DatasetGraph} that is not an instance of {@link DatasetGraphWrapper}
     */
    public final DatasetGraph getBase() { 
        DatasetGraph dsgw = dsg ;
        while (dsgw instanceof DatasetGraphWrapper) {
            dsgw = ((DatasetGraphWrapper)dsg).getWrapped() ;
        }
        return dsgw ;
    }

    /** The dataset to use for redirection - can be overridden.
     *  It is also guarantee that this is called only once per
     *  delegated call.  Changes to the wrapped object can be
     *  made based on that contract. 
     */
    protected DatasetGraph get() { return dsg ; }

    /** For operations that only read the DatasetGraph. */ 
    protected DatasetGraph getR() { return get() ; }
    
    /** For operations that write the DatasetGraph. */ 
    protected DatasetGraph getW() { return get() ; }
    
    /** For operations that get a handle on a graph. */
    protected DatasetGraph getG() { return get() ; }
    
    /** For operations that pass on transaction actions. */
    protected DatasetGraph getT() { return get() ; }

    public DatasetGraphWrapper(DatasetGraph dsg) {
        this.dsg = dsg ;
    }

    @Override
    public boolean containsGraph(Node graphNode)
    { return getR().containsGraph(graphNode) ; }

    @Override
    public Graph getDefaultGraph()
    { return getG().getDefaultGraph(); }

    @Override
    public Graph getGraph(Node graphNode)
    { return getG().getGraph(graphNode) ; }

    @Override
    public void addGraph(Node graphName, Graph graph)
    { getW().addGraph(graphName, graph) ; }

    @Override
    public void removeGraph(Node graphName)
    { getW().removeGraph(graphName) ; }

    @Override
    public void setDefaultGraph(Graph g)
    { getW().setDefaultGraph(g) ; }

    @Override
    public Lock getLock()
    { return getR().getLock() ; }

    @Override
    public Iterator<Node> listGraphNodes()
    { return getR().listGraphNodes() ; }

    @Override
    public void add(Quad quad)
    { getW().add(quad) ; }

    @Override
    public void delete(Quad quad)
    { getW().delete(quad) ; }

    @Override
    public void add(Node g, Node s, Node p, Node o)
    { getW().add(g, s, p, o) ; }

    @Override
    public void delete(Node g, Node s, Node p, Node o)
    { getW().delete(g, s, p, o) ; }
    
    @Override
    public void deleteAny(Node g, Node s, Node p, Node o)
    { getW().deleteAny(g, s, p, o) ; }

    @Override
    public void clear()
    { getW().clear() ; }
    
    @Override
    public boolean isEmpty()
    { return getR().isEmpty() ; }
    
    @Override
    public Iterator<Quad> find()
    { return getR().find() ; }

    @Override
    public Iterator<Quad> find(Quad quad)
    { return getR().find(quad) ; }

    @Override
    public Iterator<Quad> find(Node g, Node s, Node p, Node o)
    { return getR().find(g, s, p, o) ; }

    @Override
    public Iterator<Quad> findNG(Node g, Node s, Node p, Node o)
    { return getR().findNG(g, s, p, o) ; }

    @Override
    public boolean contains(Quad quad)
    { return getR().contains(quad) ; }

    @Override
    public boolean contains(Node g, Node s, Node p, Node o)
    { return getR().contains(g, s, p, o) ; }

    @Override
    public Context getContext()
    { return getR().getContext() ; }

    @Override
    public long size()
    { return getR().size() ; }

    @Override
    public void close()
    { getW().close() ; }
    
    @Override
    public String toString() { return getR().toString() ; }

    @Override
    public void sync() {
        // Pass down sync.
        SystemARQ.sync(getW()) ; 
    }

    @Override
    public void begin(ReadWrite readWrite) 
    { getT().begin(readWrite) ; }

    @Override
    public void commit() 
    { getT().commit() ; }

    @Override
    public void abort() 
    { getT().abort() ; }

    @Override
    public void end()
    { getT().end() ; }

    @Override
    public boolean isInTransaction() 
    { return get().isInTransaction() ; }    

    @Override
    public boolean supportsTransactions() {
        return getT().supportsTransactions() ;
    }

    @Override
    public boolean supportsTransactionAbort() {
        return getT().supportsTransactionAbort() ;
    }
    
}