/*
 * $Id: ELDefinitionTag.java 54933 2004-10-16 17:04:52Z germuska $ 
 *
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed 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.strutsel.taglib.tiles;

import org.apache.struts.taglib.tiles.DefinitionTag;
import javax.servlet.jsp.JspException;
import org.apache.strutsel.taglib.utils.EvalHelper;

/**
 * This is the tag handler for <tiles:definition>, which defines
 * a tiles (or template / component). Definition is put in requested context and can be
 * used in <tiles:insert&gt.
 *<p>
 * This class is a subclass of the class
 * <code>org.apache.struts.taglib.tiles.DefinitionTag</code> which provides most of
 * the described functionality.  This subclass allows all attribute values to
 * be specified as expressions utilizing the JavaServer Pages Standard Library
 * expression language.
 *
 * @version $Rev: 54933 $
 */
public class ELDefinitionTag extends DefinitionTag {

    /**
     * Instance variable mapped to "id" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String idExpr;
    /**
     * Instance variable mapped to "scope" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String scopeExpr;
    /**
     * Instance variable mapped to "template" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String templateExpr;
    /**
     * Instance variable mapped to "page" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String pageExpr;
    /**
     * Instance variable mapped to "role" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String roleExpr;
    /**
     * Instance variable mapped to "extends" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    private String extendsExpr;

    /**
     * Getter method for "id" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getIdExpr() { return (idExpr); }
    /**
     * Getter method for "scope" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getScopeExpr() { return (scopeExpr); }
    /**
     * Getter method for "template" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getTemplateExpr() { return (templateExpr); }
    /**
     * Getter method for "page" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getPageExpr() { return (pageExpr); }
    /**
     * Getter method for "role" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getRoleExpr() { return (roleExpr); }
    /**
     * Getter method for "extends" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public String getExtendsExpr() { return (extendsExpr); }

    /**
     * Setter method for "id" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setIdExpr(String idExpr) { this.idExpr = idExpr; }
    /**
     * Setter method for "scope" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setScopeExpr(String scopeExpr) { this.scopeExpr = scopeExpr; }
    /**
     * Setter method for "template" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setTemplateExpr(String templateExpr) { this.templateExpr = templateExpr; }
    /**
     * Setter method for "page" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setPageExpr(String pageExpr) { this.pageExpr = pageExpr; }
    /**
     * Setter method for "role" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setRoleExpr(String roleExpr) { this.roleExpr = roleExpr; }
    /**
     * Setter method for "extends" tag attribute.
     * (Mapping set in associated BeanInfo class.)
     */
    public void setExtendsExpr(String extendsExpr) { this.extendsExpr = extendsExpr; }

    /**
     * Resets attribute values for tag reuse.
     */
    public void release()
    {
        super.release();
        setIdExpr(null);
        setScopeExpr(null);
        setTemplateExpr(null);
        setPageExpr(null);
        setRoleExpr(null);
        setExtendsExpr(null);
    }
    
    /**
     * Process the start tag.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
        evaluateExpressions();
        return (super.doStartTag());
    }
    
    /**
     * Processes all attribute values which use the JSTL expression evaluation
     * engine to determine their values.
     *
     * @exception JspException if a JSP exception has occurred
     */
    private void evaluateExpressions() throws JspException {
        String  string  = null;

        if ((string = EvalHelper.evalString("id", getIdExpr(),
                                            this, pageContext)) != null)
            setId(string);
        if ((string = EvalHelper.evalString("scope", getScopeExpr(),
                                            this, pageContext)) != null)
            setScope(string);
        if ((string = EvalHelper.evalString("template", getTemplateExpr(),
                                            this, pageContext)) != null)
            setTemplate(string);
        if ((string = EvalHelper.evalString("page", getPageExpr(),
                                            this, pageContext)) != null)
            setPage(string);
        if ((string = EvalHelper.evalString("role", getRoleExpr(),
                                            this, pageContext)) != null)
            setRole(string);
        if ((string = EvalHelper.evalString("extends", getExtendsExpr(),
                                            this, pageContext)) != null)
            setExtends(string);
    }
}