BotServlet.java

package org.aitools.programd.server.servlet;

import java.security.Principal;

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

import org.aitools.programd.Bot;
import org.aitools.programd.Bots;
import org.aitools.programd.Core;

/**
 * @author <a href="mailto:noel@aitools.org">Noel Bush</a>
 */
public class BotServlet extends HttpServlet {

  /**
   * 
   */
  private static final long serialVersionUID = 1L;

  /** The current session. */
  protected HttpSession session;

  /** The Core object that will be used throughout. */
  protected Core core;

  /** The current botid. */
  protected String botid;

  /** The userid. */
  protected String userid;

  /** The bot object in use. */
  protected Bot bot;

  /**
   * Removes the reference to the Core, and removes it from the context attributes.
   * 
   * @see javax.servlet.GenericServlet#destroy()
   */
  @Override
  public void destroy() {
    this.getServletContext().removeAttribute("core");
    this.core = null;
  }

  /**
   * Just passes to {@link #setupBot}.
   * 
   * @throws ServletException
   * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest,
   *      javax.servlet.http.HttpServletResponse)
   */
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException {
    this.setupBot(req, resp);
  }

  /**
   * Just passes to {@link #setupBot}.
   * 
   * @throws ServletException
   * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
   *      javax.servlet.http.HttpServletResponse)
   */
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException {
    this.setupBot(req, resp);
  }

  /**
   * Gets the Core (should have already been initialized by a listener, or whatever) and keeps a reference to it.
   * 
   * @see javax.servlet.GenericServlet#init()
   */
  @Override
  public void init() {
    this.core = (Core) this.getServletContext().getAttribute("core");
  }

  /**
   * @param req the request
   * @param resp the response
   * @throws ServletException
   */
  protected void setupBot(HttpServletRequest req, HttpServletResponse resp) throws ServletException {
    // Get/create the session.
    this.session = req.getSession(true);

    // Look for a userid.
    this.userid = null;
    Principal principal = req.getUserPrincipal();
    if (principal == null) {
      // Use the session id.
      this.userid = this.session.getId();
    }
    else {
      this.userid = principal.getName();
    }
    if (this.userid == null) {
      throw new ServletException("Missing userid parameter.");
    }

    // Put the userid into a session attribute (so it can be accessed by other things; but we always recompute it!)
    this.session.setAttribute("userid", this.userid);

    // Get the bot parameter, if there is one.
    this.botid = req.getParameter("botid");

    // It might be in a request attribute.
    if (this.botid == null) {
      this.botid = (String) req.getAttribute("botid");
    }

    this.bot = null;

    // If a bot parameter is not specified, try to get any bot.
    if (this.botid == null || this.botid.length() == 0) {
      boolean noBot = true;
      Bots bots = this.core.getBots();
      if (bots != null && bots.size() > 0) {
        this.bot = this.core.getBots().getABot();
        if (this.bot != null) {
          this.botid = this.bot.getID();
          noBot = false;
        }
      }
      if (noBot) {
        throw new ServletException("No bots are available from the Core.  Cannot continue.");
      }
    }
    else if (!this.core.getBots().containsKey(this.botid)) {
      throw new ServletException("Requested botid not found.");
    }
    // otherwise...
    this.bot = this.core.getBot(this.botid);
  }
}