// JobQueue.h     Dave Reed      9/3/02
//
// JobQueue class
///////////////////////////////////////////////////////////////////////////////

#ifndef _JOBQUEUE_
#define _JOBQUEUE_

#include <fstream>
#include <string>
#include "Queue.h"
using namespace std;

enum JobStatus {OK, DONE};

class JobQueue								
{									
  public:
	JobQueue(string filename);        // constructor
	bool JobsRemaining();             // determines if any jobs in queue
	int GetCurrentID();               // gets ID of current job
	void InterruptCurrentJob();       // interrupts current job, to end of queue
	void RemoveCurrentJob();          // removes current job from queue
	JobStatus ExecuteCurrentJob();    // executes current job for one cycle
  private:
	class Job {
	  public:
	    int ID;
	    int length;
	};
	Queue<Job> jobQueue;              
};


JobQueue::JobQueue(string filename)
// Assumes: filename is the name of the job data file
// Results: constructs a queue of jobs from file
{
	ifstream infile(filename.c_str());

	int id, len;
	while (infile >> id >> len) {
		Job j;
		j.ID = id;
		j.length = len;

		jobQueue.Enter(j);
	}
}

bool JobQueue::JobsRemaining()
// Returns: true if job queue contains a job, false if empty
{
	return !jobQueue.IsEmpty();
}

int JobQueue::GetCurrentID()
// Returns: ID of current job (front of queue)
{
    return jobQueue.Front().ID;
}

void JobQueue::RemoveCurrentJob()
// Results: removes current job (at front of queue)
{
    jobQueue.Remove();
}

void JobQueue::InterruptCurrentJob()
// Results: interrupts current job, moves to end of queue
{
    jobQueue.Enter(jobQueue.Front());
	jobQueue.Remove();
}

JobStatus JobQueue::ExecuteCurrentJob()
// Returns: status after executing current job for a cycle
{
	jobQueue.Front().length--;
	if (jobQueue.Front().length == 0) {
		return DONE;
	}
	else {
		return OK;
	}
}

#endif