/*
 * $Author: bhevans $
 * $Date: 1996/05/26 22:45:39 $
 * $Source: /home/phoenix/cscstd/ijkl/jlarsen/box/RCS/Log.java,v $
 * $Revision: 1.1 $
 * $Log: Log.java,v $
# Revision 1.1  1996/05/26  22:45:39  bhevans
# Initial revision
#
 */

package com.nanosoft.pcm.machine;
import com.nanosoft.pcm.machine.*;
import java.lang.*;
import java.util.*;

/**
 * 
 The  Log  class is the intermittent object which 
 * communicates data from the report generater to the printer,
 * a fairly stupid device which is only capable of printing
 * logs.
 * 
 Log is effectively an abstract class
 * @author  $Author: bhevans $
 * @version $Revision: 1.1 $
 */
public 
class Log extends Object {
  protected int numb;          // number of Records
  protected Queue items;    // set of Records
  protected Date stamp;     // time stamp
  protected boolean posted; // records whether or not log has been posted
                            // kept for testing, not needed in production
  /**
   * Initializes the log and creates a queue to store data members
   */
  protected Log() {
  // only subclassed objects allowed
    posted = false;
    items = new Queue();
    numb = 0;
  }

  /**
   * @param obj The object to be added to the queue
   */
  protected void add(Object obj) {
  // adds one record to the log
    numb += 1;
    items.push(obj);
  }

  /**
   * Time stamps the log and sets its posted state to true.
   */
  protected void post() {
    stamp = new Date();
    posted = true;
  }

  /**
   * Precondition: The input must cast into a string nicely.
   * @param obj The object to print
   * @return A default string standard to all logs.
   */
  protected String addLine( Object obj) {
  // general formatting routine
    return "-- " + obj + "\n";
  }

  /**
   * Precondition: The queue is not empty.
   * @return The next element from the queue
   */
  protected StorageItem pop() {
  // removes one record from the log
    return (StorageItem)items.pop();
  }

  /**
   * @return Whether or not the log is posted ( ready to print ).
   */
  public boolean isPosted() { return posted; }

  /**
   * Empties the log and returns it to its inital state.
   */
  public void clean() {
  // cleans up the log, resets its state
    items.clean();
    stamp = null;
    posted = false;
    n = 0;
  }

  /**
   * Interface for printer 
 
   *  Overriden by child class 
	* @see ReportGenerator
   */
  public String headerString() {
    return "";
  }

  /**
   * Interface for printer 
 
   *  Overriden by child class 
	* @see ReportGenerator
   */
  public String footerString() {
    return "";
  }

  /**
   * Interface for printer 
 
   *  Overriden by child class 
	* @see ReportGenerator
   */
  public String dataString() {
    return "";
  }

  /**
   * Interface for printer
   * @return Whether or not the log is empty.
   */
  public boolean isEmpty() {
    return items.isEmpty();
  }

}