package hall;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.net.*;

/** Servlet that takes a search string, number of results per
 *  page, and a search engine name, sending the query to
 *  that search engine. Illustrates manipulating
 *  the response status line. It sends a 302 response
 *  (via sendRedirect) if it gets a known search engine,
 *  and sends a 404 response (via sendError) otherwise.
 *  <P>
 *  Part of tutorial on servlets and JSP that appears at
 *  http://www.apl.jhu.edu/~hall/java/Servlet-Tutorial/
 *  1999 Marty Hall; may be freely used or adapted.
 */

public class SearchEngines extends HttpServlet {
  public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    // The URLEncoder changes spaces to "+" signs and other
    // non-alphanumeric characters to "%XY", where XY is the
    // hex value of the ASCII (or ISO Latin-1) character.
    // The getParameter method decodes automatically, but since
    // we're just passing this on to another server, we need to
    // re-encode it.
    String searchString =
      URLEncoder.encode(request.getParameter("searchString"));
    String numResults =
      request.getParameter("numResults");
    String searchEngine =
      request.getParameter("searchEngine");
    SearchSpec[] commonSpecs = SearchSpec.getCommonSpecs();
    for(int i=0; i<commonSpecs.length; i++) {
      SearchSpec searchSpec = commonSpecs[i];
      if (searchSpec.getName().equals(searchEngine)) {
        // encodeURL is just planning ahead in case this servlet
        // is ever used in an application that does session tracking.
        // If cookies are turned off, session tracking is usually
        // accomplished by URL rewriting, so all URLs returned
        // by servlets should be sent through encodeURL.
        String url =
          response.encodeURL(searchSpec.makeURL(searchString,
                                                 numResults));
        response.sendRedirect(url);
        return;
      }
    }
    response.sendError(response.SC_NOT_FOUND,
                       "No recognized search engine specified.");
  }

  public void doPost(HttpServletRequest request,
                     HttpServletResponse response)
      throws ServletException, IOException {
    doGet(request, response);
  }
}