/* 
 * Copyright (c) 2001, Xiaoping Jia.  
 * All Rights Reserved. 
 */

package expo2; 

import java.io.*; 
import java.util.*; 
import javax.servlet.*; 
import javax.servlet.http.*; 
import org.apache.ecs.*;
import org.apache.ecs.html.*;


/** 
 *  Java Expo web app version 2.
 *  The Java Expo web app selecting presentation servlet.
 *  
 * @version 1.1 2001/04/20 
 * @since 1.0
 * @author Xiaoping Jia
 */ 
public class JavaExpoPresentations extends JavaExpoBase { 

  public boolean handleRequest(HttpServletRequest request, 
			       HttpServletResponse response, 
			       List contents) 
    throws ServletException, IOException { 
    contents.add(new H1("Enterprise Java Expo Presentations")); 
    JavaExpoRegister.RegistrationForm form = null;
    PresentationSet presentationSet = null; 
    HttpSession session = request.getSession(false);
    if (session == null) { 
      contents.add(new H1("Your session has expired")); 
    } else { 
      form = (JavaExpoRegister.RegistrationForm) session.getAttribute("registration form");
      presentationSet = (PresentationSet) session.getAttribute("presentation set"); 
    }
    if (form != null) { 
      if (presentationSet != null) { 
	Enumeration names = request.getParameterNames(); 
	while (names.hasMoreElements()) { 
	  String name = (String) names.nextElement(); 
	  String value = request.getParameter(name); 
	  if ("add".equals(value)) { 
	    presentationSet.add(name);
	  } else if ("remove".equals(value)) { 
	    presentationSet.remove(name);
	  }
	}
      } else { 
	presentationSet = new PresentationSet();
      }
      session.setAttribute("presentation set", presentationSet);       

      List selectedSet = presentationSet.makeTableRows(true, presentations); 
      List remainingSet = presentationSet.makeTableRows(false, presentations);       
      Form htmlform = new Form(response.encodeURL(urlPrefix + "JavaExpoPresentations"), "post"); 
      if (selectedSet == null) { 
	htmlform.addElement(new H2("No presentation selected for " + 
				   form.firstName + " " + 
				   form.lastName)); 
      } else { 
	// Build table of selected presentations
	Table table = new Table(0); 
	for (Iterator iter = selectedSet.iterator(); iter.hasNext();) { 
	  table.addElement((TR) iter.next()); 
	}      
	htmlform
	  .addElement(new H2("The following presentations are selected for " + 
			     form.firstName + " " + 
			     form.lastName)
	    .addElement(table));       
      }
      if (remainingSet != null) { 
	// Build table of remaining presentations
	Table table = new Table(0); 
	for (Iterator iter = remainingSet.iterator(); iter.hasNext();) { 
	  table.addElement((TR) iter.next()); 
	}      
	htmlform
	  .addElement(new H2("Select from the following presentations:")
	    .addElement(table));       
      }
      contents.add(htmlform);     
    }
    return true; 
  }

  static class Presentation implements Serializable { 
    Presentation(String id, String title, String time) { 
      this.id = id; 
      this.title = title;
      this.time = time;
    }
    String id; 
    String title;
    String time; 
  }

  // the list of all presentations 
  protected List presentations = new ArrayList(); 

  public void init() { 
    super.init(); 
    try {
      ServletContext ctx = getServletContext(); 
      BufferedReader mfile = 
	new BufferedReader(new FileReader(ctx.getRealPath("WEB-INF/presentations.dat"))); 
      String line; 
      while ((line = mfile.readLine()) != null) { 
	line = line.trim();  
	if (line.length() > 0 && 
	    line.charAt(0) != '#') { 
	  int i1 = line.indexOf(':'); 
	  if (i1 > 0) { 
	    int i2 = line.indexOf(':', i1 + 1); 
	    if (i2 > i1) { 
	      String id = line.substring(0, i1).trim(); 
	      String title = line.substring(i1 + 1, i2).trim(); 
	      String time = line.substring(i2 + 1).trim(); 
	      presentations.add(new Presentation(id, title, time)); 
	    }
	  }
	}
	// skip empty or comment line	  
      }
    } catch (FileNotFoundException e) {
      System.out.println("Unable to open file presentations.dat"); 
    } catch (IOException e) {
      System.out.println("Error in reading file presentations.dat"); 
    } 
  }

  static class PresentationSet implements Serializable {
    Set selected = new HashSet(); 
    // set of presentation id's representing selected presentations  

    void add(String id) { 
      if (id != null) { 
	selected.add(id); 
      }
    }

    void remove(String id) { 
      if (id != null) { 
	selected.remove(id); 
      }
    }
    
    // flag == true:  selected list
    // flas == false: unselected list 
    List makeTableRows(boolean flag, List presentations) { 
      List list = new ArrayList(); 
      Iterator iter = presentations.iterator(); 
      while (iter.hasNext()) { 
	Presentation prz = (Presentation) iter.next(); 
	String id = prz.id; 
	boolean in = selected.contains(id);  
	if (flag == in) { 
	  list.add(new TR()
	    .addElement(new TD()
	      .addElement(new Input(Input.submit, prz.id, flag ? "remove" : "add")))
	    .addElement(new TD(prz.title))
	    .addElement(new TD(new I().addElement(prz.time))));
	}
      }
      if (list.size() > 0) { 
	return list; 
      } else { 
	return null; 
      }
    }
      
  }

}