/*

 * Copyright (c) 2002 TwelveMonkeys.

 * All rights reserved.

 *

 * $Log: IncludeTag.java,v $

 * Revision 1.2  2003/10/06 14:25:36  WMHAKUR

 * Code clean-up only.

 *

 * Revision 1.1  2002/10/18 14:03:09  WMHAKUR

 * Moved to com.twelvemonkeys.servlet.jsp.droplet.taglib

 *

 *

 */



package com.twelvemonkeys.servlet.jsp.droplet.taglib;



import com.twelvemonkeys.servlet.jsp.taglib.ExTagSupport;



import javax.servlet.ServletException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.jsp.JspException;

import java.io.IOException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.Iterator;



/**

 * Include tag tag that emulates ATG Dynamo Droplet tag JHTML behaviour for

 * JSP.

 *

 * @author Thomas Purcell (CSC Australia)

 * @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>

 * @author last modified by $Author: haku $

 *

 * @version $Revision: #1 $, ($Date: 2008/05/05 $)

 *

 */

public class IncludeTag extends ExTagSupport {

    /**

     * This will contain the names of all the parameters that have been

     * added to the PageContext.REQUEST_SCOPE scope by this tag.

     */

    private ArrayList<String> parameterNames = null;



    /**

     * If any of the parameters we insert for this tag already exist, then

     * we back up the older parameter in this {@code HashMap} and

     * restore them when the tag is finished.

     */

    private HashMap<String, Object> oldParameters = null;



    /**

     * This is the URL for the JSP page that the parameters contained in this

     * tag are to be inserted into.

     */

    private String page;



    /**

     * The name of the PageContext attribute

     */

    public final static String PAGE_CONTEXT = "com.twelvemonkeys.servlet.jsp.PageContext";



    /**

     * Sets the value for the JSP page to insert the parameters into.  This

     * will be set by the tag attribute within the original JSP page.

     *

     * @param pPage The URL for the JSP page to insert parameters into.

     */

    public void setPage(String pPage) {

        page = pPage;

    }



    /**

     * Adds a parameter to the {@code PageContext.REQUEST_SCOPE} scope.

     * If a parameter with the same name as {@code pName} already exists,

     * then the old parameter is first placed in the {@code OldParameters}

     * member variable.  When this tag is finished, the old value will be

     * restored.

     *

     * @param pName The name of the new parameter to be stored in the

     *     {@code PageContext.REQUEST_SCOPE} scope.

     * @param pValue The value for the parmeter to be stored in the {@code

     *     PageContext.REQUEST_SCOPE} scope.

     */

    public void addParameter(String pName, Object pValue) {

        // Check that we haven't already saved this parameter

        if (!parameterNames.contains(pName)) {

            parameterNames.add(pName);



            // Now check if this parameter already exists in the page.

            Object obj = getRequest().getAttribute(pName);

            if (obj != null) {

                oldParameters.put(pName, obj);

            }

        }



        // Finally, insert the parameter in the request scope.

        getRequest().setAttribute(pName, pValue);

    }



    /**

     * This is the method called when the JSP interpreter first hits the tag

     * associated with this class.  This method will firstly determine whether

     * the page referenced by the {@code page} attribute exists.  If the

     * page doesn't exist, this method will throw a {@code JspException}.

     * If the page does exist, this method will hand control over to that JSP

     * page.

     *

     * @exception JspException

     */

    public int doStartTag() throws JspException {

        oldParameters = new HashMap<String, Object>();

        parameterNames = new ArrayList<String>();



        return EVAL_BODY_INCLUDE;

    }



    /**

     * This method is called when the JSP page compiler hits the end tag.  By

     * now all the data should have been passed and parameters entered into

     * the {@code PageContext.REQUEST_SCOPE} scope.  This method includes

     * the JSP page whose URL is stored in the {@code mPage} member

     * variable.

     *

     * @exception JspException

     */

    public int doEndTag() throws JspException {

        String msg;



        try {

            Iterator<String> iterator;

            String parameterName;



            // -- Harald K 20020726

            // Include the page, in place

            //getDispatcher().include(getRequest(), getResponse());

            addParameter(PAGE_CONTEXT, pageContext); // Will be cleared later

            pageContext.include(page);



            // Remove all the parameters that were added to the request scope

            // for this insert tag.

            iterator = parameterNames.iterator();



            while (iterator.hasNext()) {

                parameterName = iterator.next();



                getRequest().removeAttribute(parameterName);

            }



            iterator = oldParameters.keySet().iterator();



            // Restore the parameters we temporarily replaced (if any).

            while (iterator.hasNext()) {

                parameterName = iterator.next();



                getRequest().setAttribute(parameterName, oldParameters.get(parameterName));

            }



            return super.doEndTag();

        }

        catch (IOException ioe) {

            msg = "Caught an IOException while including " + page

                    + "\n" + ioe.toString();

            log(msg, ioe);

            throw new JspException(msg);

        }

        catch (ServletException se) {

            msg = "Caught a ServletException while including " + page

                    + "\n" + se.toString();

            log(msg, se);

            throw new JspException(msg);

        }

    }



    /**

     * Free up the member variables that we've used throughout this tag.

     */

    protected void clearServiceState() {

        oldParameters = null;

        parameterNames = null;

    }



    /**

     * Returns the request dispatcher for the JSP page whose URL is stored in

     * the {@code mPage} member variable.

     *

     * @return The RequestDispatcher for the JSP page whose URL is stored in

     *     the {@code mPage} member variable.

     */

    /*

    private RequestDispatcher getDispatcher() {

        return getRequest().getRequestDispatcher(page);

    }

    */



    /**

     * Returns the HttpServletRequest object for the current user request.

     *

     * @return The HttpServletRequest object for the current user request.

     */

    private HttpServletRequest getRequest() {

        return (HttpServletRequest) pageContext.getRequest();

    }



    /**

     * Returns the HttpServletResponse object for the current user request.

     *

     * @return The HttpServletResponse object for the current user request.

     */

    private HttpServletResponse getResponse() {

        return (HttpServletResponse) pageContext.getResponse();

    }

}