/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */
package org.dspace.app.webui.submit;

import java.io.IOException;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.dspace.app.util.SubmissionInfo;
import org.dspace.authorize.AuthorizeException;
import org.dspace.core.Context;

/**
 * Abstract 'binding' class for DSpace Submission Steps which use the JSP-UI.
 * <P>
 * These methods revolve around the following: (1) pre-processing of data to
 * prepare for display, (2) displaying the JSP, and (3) post-processing of any
 * user input (or alternatively backend processing, for non-interactive steps).
 * <P>
 * For the JSP UI, the job of this class is to maintain the context of where the
 * user is within the current "step" of the submission process. Each "step" can
 * consist of multiple "pages" (which roughly correspond to HTML displays), so
 * this class helps manage which page the user should see next.
 * <P>
 * The methods of the JSPStepManager are called in this order:
 * <ul>
 * <li>Call doPreProcessing() method</li>
 * <li>If showJSP() was specified from doPreProcessing(), then the JSP
 * specified will be displayed</li>
 * <li>If showJSP() was not specified from doPreProcessing(), then the
 * doProcessing() method is called an the step completes immediately</li>
 * <li>Call doProcessing() method on appropriate AbstractProcessingStep after the user returns from the JSP, in order
 * to process the user input</li>
 * <li>Call doPostProcessing() method to determine if more user interaction is
 * required, and if further JSPs need to be called.</li>
 * <li>If there are more "pages" in this step then, the process begins again
 * (for the new page).</li>
 * <li>Once all pages are complete, control is forwarded back to the
 * SubmissionController, and the next step is called.</li>
 * </ul>
 * 
 * @see org.dspace.submit.AbstractProcessingStep
 * @see org.dspace.app.webui.servlet.SubmissionController
 * @see org.dspace.app.util.SubmissionConfig
 * @see org.dspace.app.util.SubmissionStepConfig
 * 
 * @author Tim Donohue
 * @version $Revision$
 */
public abstract class JSPStep 
{
    /**
     * Value to return from doPreProcessing to specify not to load any JSP Page
     * (equal to "") *
     */
    public static final String NO_JSP = "";

    /**
     * Do any pre-processing to determine which JSP (if any) is used to generate
     * the UI for this step. This method should include the gathering and
     * validating of all data required by the JSP. In addition, if the JSP
     * requires any variable to passed to it on the Request, this method should
     * set those variables.
     * <P>
     * If this step requires user interaction, then this method must call the
     * JSP to display, using the "showJSP()" method of the JSPStepManager class.
     * <P>
     * If this step doesn't require user interaction OR you are solely using
     * Manakin for your user interface, then this method may be left EMPTY,
     * since all step processing should occur in the doProcessing() method.
     * 
     * @param context
     *            current DSpace context
     * @param request
     *            current servlet request object
     * @param response
     *            current servlet response object
     * @param subInfo
     *            submission info object
     */
    public abstract void doPreProcessing(Context context, HttpServletRequest request,
            HttpServletResponse response, SubmissionInfo subInfo)
            throws ServletException, IOException, SQLException,
            AuthorizeException;
   
    /**
     * Do any post-processing after the step's backend processing occurred (in
     * the doProcessing() method).
     * <P>
     * It is this method's job to determine whether processing completed
     * successfully, or display another JSP informing the users of any potential
     * problems/errors.
     * <P>
     * If this step doesn't require user interaction OR you are solely using
     * Manakin for your user interface, then this method may be left EMPTY,
     * since all step processing should occur in the doProcessing() method.
     * 
     * @param context
     *            current DSpace context
     * @param request
     *            current servlet request object
     * @param response
     *            current servlet response object
     * @param subInfo
     *            submission info object
     * @param status
     *            any status/errors reported by doProcessing() method
     */
    public abstract void doPostProcessing(Context context, HttpServletRequest request,
            HttpServletResponse response, SubmissionInfo subInfo, int status)
            throws ServletException, IOException, SQLException,
            AuthorizeException;
    
    
    /**
     * Return the URL path (e.g. /submit/review-metadata.jsp) of the JSP
     * which will review the information that was gathered in this Step.
     * <P>
     * This Review JSP is loaded by the 'Verify' Step, in order to dynamically
     * generate a submission verification page consisting of the information
     * gathered in all the enabled submission steps.
     * 
     * @param context
     *            current DSpace context
     * @param request
     *            current servlet request object
     * @param response
     *            current servlet response object
     * @param subInfo
     *            submission info object
     */
    public abstract String getReviewJSP(Context context, HttpServletRequest request,
            HttpServletResponse response, SubmissionInfo subInfo);
}