[TAP] Add home page configuration in the TAP configuration file. (missing...

package tap.resource;

/*

 * This file is part of TAPLibrary.

 * 

 * TAPLibrary is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 * 

 * TAPLibrary is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU Lesser General Public License for more details.

 * 

 * You should have received a copy of the GNU Lesser General Public License

 * along with TAPLibrary.  If not, see <http://www.gnu.org/licenses/>.

 * 

 * Copyright 2015 - Astronomisches Rechen Institut (ARI)

 */

import java.io.BufferedInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.PrintWriter;

import java.net.URI;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import tap.TAPException;

import uws.service.log.UWSLog.LogLevel;

/**

 * <p>Write the content of the TAP service's home page.</p>

 * 

 * <p><i>Note:

 * 	This class is using the two following {@link TAP} attributes in order to display the home page:

 * 	{@link TAP#homePageURI} and {@link TAP#homePageMimeType}. The MIME type is used only for the third case below (local file). 

 * </i></p>

 * 

 * <p>Four cases are taken into account in this class, in function of the {@link TAP#homePageURI} value:</p>

 * <ol>

 * 	<li><b>a default content</b> if no custom home page (URI) has been specified using {@link TAP#setHomePageURI(String)}.

 * 	                             This default home page is hard-coded in this class and displays just an HTML list of

 * 	                             links. There is one link for each resources of this TAP service (excluding the home page).</li>

 * 	<li><b>a file inside WebContent</b> if the given URI has no scheme (e.g. "tapIndex.jsp" or "/myFiles/tapIndex.html").

 * 	                                    The URI is then an absolute (if starting with "/") or a relative path to file inside the WebContent directory.

 * 	                                    In this case the request is forwarded to this file. It is neither a redirection nor a copy,

 * 	                                    but a kind of inclusion of the interpreted file into the response.

 *                                      <i>This method MUST be used if your home page is a JSP.</i></li>

 * <li><b>a local file</b> if a URI starts with "file:". In this case, the content of the local file is copied in the HTTP response. There is no interpretation. So this method should not be used for JSP.</li>	

 * <li><b>a distance document</b> in all other cases. Indeed, if there is a scheme different from "file:" the given URI will be considered as a URL.

 *                                In this case, any request to the TAP home page is redirected to this URL.</li>

 * </ol>

 * 

 * @author Grégory Mantelet (ARI)

 * @version 2.0 (02/2015)

 * @since 2.0

 */

public class HomePage implements TAPResource {

	/** Name of this TAP resource. */

	public static final String RESOURCE_NAME = "HOME PAGE";

	/** TAP service owning this resource. */

	protected final TAP tap;

	public HomePage(final TAP tap){

		if (tap == null)

			throw new NullPointerException("Missing TAP object! The HOME PAGE resource can not be initialized without a TAP instance.");

		this.tap = tap;

	}

	@Override

	public void init(final ServletConfig config) throws ServletException{}

	@Override

	public void destroy(){}

	@Override

	public void setTAPBaseURL(String baseURL){}

	@Override

	public final String getName(){

		return RESOURCE_NAME;

	}

	@Override

	public boolean executeResource(final HttpServletRequest request, final HttpServletResponse response) throws IOException, TAPException{

		PrintWriter writer = response.getWriter();

		boolean written = false;

		// Display the specified home page, if any is specified:

		if (tap.homePageURI != null){

			URI uri = null;

			try{

				uri = new URI(tap.homePageURI);

				/* CASE: FILE IN WebContent */

				if (uri.getScheme() == null){

					if (request.getServletContext().getResource(tap.homePageURI) != null){

						request.getRequestDispatcher(tap.homePageURI).forward(request, response);

						written = true;

					}else

						tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): Web application file not found!", null);

				}

				/* CASE: LOCAL FILE */

				else if (uri.getScheme().equalsIgnoreCase("file")){

					// Set the content type:

					response.setContentType(tap.homePageMimeType);

					// Get an input toward the custom home page:

					BufferedInputStream input = null;

					try{

						File f = new File(uri.getPath());

						if (f.exists() && !f.isDirectory() && f.canRead()){

							// set the content length:

							response.setContentLength((int)f.length());

							// get the input stream:

							input = new BufferedInputStream(new FileInputStream(f));

							// Copy the content of the input into the given writer:

							byte[] buffer = new byte[2048];

							int nbReads = 0;

							while((nbReads = input.read(buffer)) > 0)

								writer.print(new String(buffer, 0, nbReads));

							// copy successful:

							written = true;

						}else

							tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): File not found or not readable (" + f.exists() + !f.isDirectory() + f.canRead() + ")!", null);

					}finally{

						if (input != null)

							input.close();

					}

				}

				/* CASE: HTTP/HTTPS/FTP/... */

				else{

					response.sendRedirect(tap.homePageURI);

					written = true;

				}

			}catch(Exception e){

				tap.getLogger().logTAP(LogLevel.ERROR, null, "HOME_PAGE", "Can not write the specified home page content (" + tap.homePageURI + "): " + e.getMessage(), e);

			}

		}

		// DEFAULT: list all available resources:

		if (!written){

			// Set the content type: HTML document

			response.setContentType("text/html");

			// Write the home page:

			writer.println("<html><head><title>TAP HOME PAGE</title></head><body><h1 style=\"text-align: center\">TAP HOME PAGE</h1><h2>Available resources:</h2><ul>");

			for(TAPResource res : tap.resources.values())

				writer.println("<li><a href=\"" + tap.tapBaseURL + "/" + res.getName() + "\">" + res.getName() + "</a></li>");

			writer.println("</ul></body></html>");

			written = true;

		}

		return written;

	}

}