/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the 
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact visigoths@visigoths.org.
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.core;

import java.io.IOException;
import freemarker.template.*;


/**
 * An instruction to visit an XML node.
 */
final class VisitNode extends TemplateElement {
    
    Expression targetNode, namespaces;
    
    VisitNode(Expression targetNode, Expression namespaces) {
        this.targetNode = targetNode;
        this.namespaces = namespaces;
    }

    void accept(Environment env) throws IOException, TemplateException {
        TemplateModel node = targetNode.getAsTemplateModel(env);
        assertNonNull(node, targetNode, env);
        if (!(node instanceof TemplateNodeModel)) {
            throw new TemplateException("Expecting an XML node here", env);
        }
        TemplateModel nss = namespaces == null ? null : namespaces.getAsTemplateModel(env);
        if (namespaces instanceof StringLiteral) {
            nss = env.importLib(((TemplateScalarModel) nss).getAsString(), null);
        }
        else if (namespaces instanceof ListLiteral) {
            nss = ((ListLiteral) namespaces).evaluateStringsToNamespaces(env);
        }
        if (nss != null) {
            if (nss instanceof Environment.Namespace) {
                SimpleSequence ss = new SimpleSequence(1);
                ss.add(nss);
                nss = ss;
            }
            else if (!(nss instanceof TemplateSequenceModel)) {
                throw new TemplateException("Expecting a sequence of namespaces after 'using'", env);
            }
        }
        env.visit((TemplateNodeModel) node, (TemplateSequenceModel) nss);
    }

    public String getCanonicalForm() {
        if (namespaces == null) {
            return "<#visit " + targetNode.getCanonicalForm() + "/>";
        }
        return "<#visit " + targetNode.getCanonicalForm() + " using " + namespaces.getCanonicalForm() + "/>";
    }

    public String getDescription() {
        return "visit instruction";
    }
}
