/*
 * $Id: SizeTag.java 54929 2004-10-16 16:38:42Z 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.struts.taglib.bean;


import java.lang.reflect.Array;
import java.util.Collection;
import java.util.Map;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;
import org.apache.struts.util.MessageResources;
import org.apache.struts.taglib.TagUtils;


/**
 * Define a scripting variable that will contain the number of elements
 * found in a specified array, Collection, or Map.
 *
 * @version $Rev: 54929 $ $Date: 2004-10-16 17:38:42 +0100 (Sat, 16 Oct 2004) $
 */

public class SizeTag extends TagSupport {


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


    /**
     * The actual collection to be counted.
     */
    protected Object collection = null;

    public Object getCollection() {
        return (this.collection);
    }

    public void setCollection(Object collection) {
        this.collection = collection;
    }


    /**
     * The name of the scripting variable that will be exposed as a page
     * scope attribute.
     */
    protected String id = null;

    public String getId() {
        return (this.id);
    }

    public void setId(String id) {
        this.id = id;
    }


    /**
     * The message resources for this package.
     */
    protected static MessageResources messages =
	MessageResources.getMessageResources
	("org.apache.struts.taglib.bean.LocalStrings");



    /**
     * The name of the bean owning the property to be counted.
     */
    protected String name = null;

    public String getName() {
        return (this.name);
    }

    public void setName(String name) {
        this.name = name;
    }


    /**
     * The name of the property to be retrieved.
     */
    protected String property = null;

    public String getProperty() {
        return (this.property);
    }

    public void setProperty(String property) {
        this.property = property;
    }


    /**
     * The scope within which to search for the specified bean.
     */
    protected String scope = null;

    public String getScope() {
        return (this.scope);
    }

    public void setScope(String scope) {
        this.scope = scope;
    }


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


    /**
     * Retrieve the required property and expose it as a scripting variable.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {

        // Retrieve the required property value
        Object value = this.collection;
        if (value == null) {
            if (name == null) {
                // Must specify either a collection attribute or a name
                // attribute.
                JspException e = new JspException
                    (messages.getMessage("size.noCollectionOrName"));
                TagUtils.getInstance().saveException(pageContext, e);
                throw e;
            }
            
            value = TagUtils.getInstance().lookup(pageContext, name, property, scope);
        }

        // Identify the number of elements, based on the collection type
        int size = 0;
        if (value == null) {
            JspException e = new JspException
                (messages.getMessage("size.collection"));
            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        } else if (value.getClass().isArray()) {
            size = Array.getLength(value);
        } else if (value instanceof Collection) {
            size = ((Collection) value).size();
        } else if (value instanceof Map) {
            size = ((Map) value).size();
        } else {
            JspException e = new JspException
                (messages.getMessage("size.collection"));
            TagUtils.getInstance().saveException(pageContext, e);
            throw e;
        }

        // Expose this size as a scripting variable
        pageContext.setAttribute(this.id, new Integer(size),
                                 PageContext.PAGE_SCOPE);
        return (SKIP_BODY);

    }


    /**
     * Release all allocated resources.
     */
    public void release() {

        super.release();
        collection = null;
        id = null;
        name = null;
        property = null;
        scope = null;

    }


}