/*
 * 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.arq.querybuilder.handlers;

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

import org.apache.jena.arq.querybuilder.rewriters.AbstractRewriter;
import org.apache.jena.graph.Node;
import org.apache.jena.graph.Triple;
import org.apache.jena.query.Query;
import org.apache.jena.sparql.core.BasicPattern;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.syntax.Template;

/**
 * The handler for construct clauses.
 *
 */
public class ConstructHandler implements Handler {
    private final Query query;
    private List<Triple> constructs;

    /**
     * The constructor
     * 
     * @param query The query that this handler will be modifying.
     */
    public ConstructHandler(Query query) {
        this.query = query;
        constructs = new ArrayList<>();
        if (query.getConstructTemplate() != null) {
            for (Triple t : query.getConstructTemplate().getTriples()) {
                constructs.add(t);
            }
        }
    }

    /**
     * Add a triple to the construct statement.
     * 
     * @param t The triple to add.
     */
    public void addConstruct(Triple t) {
        constructs.add(t);
        query.setConstructTemplate(new Template(BasicPattern.wrap(constructs)));
    }

    /**
     * Add all the construct handlers from the handler argument to this construct.
     * 
     * @param handler The construct handler to copy from.
     */
    public void addAll(ConstructHandler handler) {
        constructs.addAll(handler.constructs);
        query.setConstructTemplate(new Template(BasicPattern.wrap(constructs)));
    }

    @Override
    public void setVars(Map<Var, Node> values) {
        if (values.isEmpty()) {
            return;
        }
        AbstractRewriter<Node> rw = new AbstractRewriter<Node>(values) {
        };
        query.setConstructTemplate(new Template(BasicPattern.wrap(rw.rewrite(constructs))));
    }

    @Override
    public void build() {
        // there are no special operations for the build.
    }

}
