import java.io.*;

class Scheduler {
	 private static final int QUANTUM = 20;

	 public static void main(String[] args) {
		  // make sure the right number of arguments were passed in
		  if(args.length != 1) {
				System.err.println("Error: usage - Scheduler <testFile>");
				System.exit(1);
		  }

		  // open the test file for reading
		  BufferedReader in = null;
		  try {
				in = new BufferedReader(new FileReader(args[0]));
		  } catch(FileNotFoundException e) {
				System.err.println("Error: file " + args[0] + " not found.");
				System.exit(1);
		  }

		  // now set up the events object
		  Events events = new Events(in, QUANTUM);

		  // start the main loop
		  DoubleCircularList dcList = new DoubleCircularList();
		  mainLoop(events, dcList);
	 }

	 /*
	  * mainLoop
	  *
	  * Processes every event until there are no more to process. This
	  * occurs when the list is empty and there are no more entries in the
	  * test file.
	  */
	 private static void mainLoop(Events events, DoubleCircularList list) {
		  Job j;
		  int lastEventTime = 0;
		  int e;

		  while((e = events.getNextEvent((Job)list.getCurrent())) >= 0) {
				switch(e) {
				case Events.JOB_ENTER:
					 j = events.getJob();
					 System.out.println("Job entering(time = " +
											  events.getTime() + "): " + j.toString());

					 // may need to reset the quantum or update current run time
					 if(list.getCurrent() == null)
						  events.newQuantum();
					 else
						  ((Job)list.getCurrent()).updateRunTime(events.getTime() - lastEventTime);

					 list.add(j);
					 printCurrentState(list);
					 break;
					 
				case Events.JOB_FINISH:
					 j = (Job)list.removeCurrent();
					 j.updateRunTime(j.getRemaining());
					 System.out.println("Job finished(time = " +
											  events.getTime() + "): " + j.toString());
					 //j = null;
					 printCurrentState(list);
					 break;

				case Events.QUANTUM_EXPIRE:
					 j = (Job)list.getCurrent();
					 if(j != null) {
						  j.updateRunTime(events.getTime() - lastEventTime);
						  System.out.println("Job being replaced(time = " +
													events.getTime() + "): " +
													j.toString());
						  list.next();
						  j = (Job)list.getCurrent();
						  System.out.println("Job being restarted(time = " +
													events.getTime() + "): " + j.toString());
						  printCurrentState(list);
					 }
					 break;
				}
				lastEventTime = events.getTime();
				System.out.println();
		  }
	 }

	 private static void printCurrentState(DoubleCircularList list) {
		  System.out.println("Current state of system:");
		  if(list.isEmpty())
				System.out.println("  No jobs in the system.");
		  list.printList();
	 }
}