/**
  Data relating to a course being taught.
 
  @author Amitabha Mukerjee
  @version October 2008
 */
public class Course
{
    // instance variables - replace the example below with your own
    private String name;
    private String number;
    private String dept;
    private Student[] roster;
    private int strength;
    private Date startDate;
    private Date endDate;
    private Date[] examDates = new Date[3];

    /**
      Constructor 
     */
    public Course(String courseNum)
    {
        // initialise instance variables
        name = courseNum;
        dept = courseNum.substring(0,3);
        if (dept.equalsIgnoreCase("ESc")) dept = "";
        else if (dept.equalsIgnoreCase("TA2")) dept = "";
    }

    public void add(Student s)
    {
        if (roster == null)  // first student in course
        {   
            roster = new Student[1];
            roster[0] = s;
        }
        else 
        {
            Student[] r = new Student[ roster.length+1 ];
            int i = 0;
            String str = s.getRollNum();
            while( i<roster.length && str.compareTo( ((Student)roster[i]).getRollNum() ) > 0) 
                r[i] = (Student)roster[i++];
            r[i] = s;
            for (i = i+1; i< r.length; i++)
                r[i] = (Student)roster[i-1];
            roster = r; 
        }
    }

    /**
     adds a new student to a course.  Maintains sorted roster
    */
    public void addBinary(Student s)
    {
        if (roster == null)  // first student in course
        {   
            roster = new Student[1];
            roster[0] = s;
        }
        else 
        {
            // binary search
            Student[] r = new Student[ roster.length+1 ];
            int insertPos = findPos (s, 0, roster.length);
            for (int i = 0; i<insertPos; i++)
                r[i] = (Student)roster[i];
            r[insertPos] = s;
            for (int i = insertPos+1; i< r.length; i++)
                r[i] = (Student)roster[i-1];
            roster = r;
        }            
    }

    /** returns the position s.t. s >= the item before it 
        uses binary search
    */
    public int findPos( Student s, int lo, int hi)
    {
        if (hi == lo)
            return hi;
        int mid = (hi+lo)/2;
        int grtr = s.getRollNum().compareTo( ((Student)roster[mid]).getRollNum() );
        if (grtr == 0) 
            return mid;
        else
        {
            if (grtr < 0) return findPos(s, lo, mid);
            else return findPos(s, mid+1, hi);
        }
    }


    /**
     adds a new student to a course.  Does not try to maintain the
        sorted position
    */

    /** sort entries in the roster in ascending order of roll number */
    public void sortRoster()
    {
        int minIndex = 0;
        int sortedUpto = 0;
        String minRollNum;

        while (sortedUpto < roster.length-1)
        {
            minRollNum=((Student)roster[sortedUpto]).getRollNum();
            minIndex = sortedUpto;
            for (int i=sortedUpto+1; i< roster.length; i++)
            {   if (((Student)roster[i]).getRollNum().compareTo(minRollNum) < 0)
                {
                    minIndex = i;
                    minRollNum = ((Student)roster[i]).getRollNum();
                }
            }
            if (minIndex != sortedUpto)
                exchangeRoster(sortedUpto, minIndex);
            sortedUpto++;
        }
    }

    /** exchange roster entries i and j */
    private void exchangeRoster(int i, int j)
    {
        Student exch = (Student)roster[i];
        roster[i] = roster[j];
        roster[j] = exch;
    }

    public String toString()
    {
        return (number + ":    " + name + "\n" );
    }

    /** print the roster */
    public void printRoster()
    {   for (int i = 0; i < roster.length ;i++)
            System.out.print(i + ": " + ((Student)roster[i]).getRollNum() + "  " );
        System.out.println();
    }

    /** Test function
    */
    public static void main(String args[])
    {   System.out.println();
        Student y2 = new Student("y2");
        Student y3 = new Student("y3");
        Student y0 = new Student("y0"); 
        Student a1 = new Student("a1"); 
        Course esc101 = new Course("esc101");
        esc101.add(y2); 
        esc101.printRoster();
        esc101.add(a1);
        esc101.printRoster();
        esc101.add(y3);
        esc101.printRoster();
        esc101.add(y0); 
        esc101.printRoster();
        esc101.add(y3); 
        esc101.printRoster();
    }
}