/*
 * 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.tomcat.util.digester;

import org.apache.tomcat.util.res.StringManager;
import org.xml.sax.Attributes;

/**
 * Concrete implementations of this class implement actions to be taken when a corresponding nested pattern of XML
 * elements has been matched.
 */
public abstract class Rule {

    /**
     * StringManager for internationalized messages.
     */
    protected static final StringManager sm = StringManager.getManager(Rule.class);

    // ----------------------------------------------------------- Constructors

    /**
     * <p>
     * Base constructor. Now the digester will be set when the rule is added.
     * </p>
     */
    public Rule() {
    }


    // ----------------------------------------------------- Instance Variables


    /**
     * The Digester with which this Rule is associated.
     */
    protected Digester digester = null;


    /**
     * The namespace URI for which this Rule is relevant, if any.
     */
    protected String namespaceURI = null;


    // ------------------------------------------------------------- Properties

    /**
     * Identify the Digester with which this Rule is associated.
     *
     * @return the Digester with which this Rule is associated.
     */
    public Digester getDigester() {
        return digester;
    }


    /**
     * Set the <code>Digester</code> with which this <code>Rule</code> is associated.
     *
     * @param digester The digester with which to associate this rule
     */
    public void setDigester(Digester digester) {
        this.digester = digester;
    }


    /**
     * Return the namespace URI for which this Rule is relevant, if any.
     *
     * @return The namespace URI for which this rule is relevant or <code>null</code> if none.
     */
    public String getNamespaceURI() {
        return namespaceURI;
    }


    /**
     * Set the namespace URI for which this Rule is relevant, if any.
     *
     * @param namespaceURI Namespace URI for which this Rule is relevant, or <code>null</code> to match independent of
     *                         namespace.
     */
    public void setNamespaceURI(String namespaceURI) {
        this.namespaceURI = namespaceURI;
    }


    // --------------------------------------------------------- Public Methods

    /**
     * This method is called when the beginning of a matching XML element is encountered. The default implementation is
     * a NO-OP.
     *
     * @param namespace  the namespace URI of the matching element, or an empty string if the parser is not namespace
     *                       aware or the element has no namespace
     * @param name       the local name if the parser is namespace aware, or just the element name otherwise
     * @param attributes The attribute list of this element
     *
     * @throws Exception if an error occurs while processing the event
     */
    public void begin(String namespace, String name, Attributes attributes) throws Exception {
        // NO-OP by default.
    }


    /**
     * This method is called when the body of a matching XML element is encountered. If the element has no body, this
     * method is not called at all. The default implementation is a NO-OP.
     *
     * @param namespace the namespace URI of the matching element, or an empty string if the parser is not namespace
     *                      aware or the element has no namespace
     * @param name      the local name if the parser is namespace aware, or just the element name otherwise
     * @param text      The text of the body of this element
     *
     * @throws Exception if an error occurs while processing the event
     */
    public void body(String namespace, String name, String text) throws Exception {
        // NO-OP by default.
    }


    /**
     * This method is called when the end of a matching XML element is encountered. The default implementation is a
     * NO-OP.
     *
     * @param namespace the namespace URI of the matching element, or an empty string if the parser is not namespace
     *                      aware or the element has no namespace
     * @param name      the local name if the parser is namespace aware, or just the element name otherwise
     *
     * @throws Exception if an error occurs while processing the event
     */
    public void end(String namespace, String name) throws Exception {
        // NO-OP by default.
    }


    /**
     * This method is called after all parsing methods have been called, to allow Rules to remove temporary data.
     *
     * @throws Exception if an error occurs while processing the event
     */
    public void finish() throws Exception {
        // NO-OP by default.
    }
}
