/* An instance of this class represents a time of day, precise to the
** minute (e.g., 7:38am).
**
** Authors: R. McCloskey and < STUDENTS' NAMES >
*/

public class TimeOfDay {

   // class constants
   // ---------------

   static final int MINUTES_PER_HOUR = 60;
   static final int HOURS_PER_HALF_DAY = 12;
   static final int MINUTES_PER_DAY = 2 * HOURS_PER_HALF_DAY * MINUTES_PER_HOUR;

   // instance variable
   // -----------------
   int minutesSinceMidnight;  // class invariant:
                              // 0 <= minutesSinceMidnight < MINUTES_PER_DAY
  

   // constructors
   // ------------

   /* Initializes this TimeOfDay object to represent the time of day 
   ** described by the three parameters.
   ** precondition: 1 <= h <= HOURS_PER_HALF_DAY && 0 <= m < MINUTES_PER_HOUR
   */
   public TimeOfDay(int h, int m, boolean isAM) {
      setTo(h,m,isAM);
   }

   /* Initializes this object to represent noon.
   */
   public TimeOfDay() {
      this(HOURS_PER_HALF_DAY, 0, false);
   }


   // observers
   // ---------

   /* Returns a String describing the time of day represented by this object.
   ** Examples:  "7:38AM", "11:06PM"
   */
   public String toString() {
      String hourStr, minuteStr, amPmStr;

      // MISSING code to assign appropriate values to the 
      // three local variables declared above.

      return hourStr + ':' + minuteStr + amPmStr;
   }

   /* Returns a String describing the time of day represented by this object,
   ** in the 24-hour format (sometimes referred to as the "military" format).
   ** Such a string has the form hh:mm, where hh is a two-digit numeral
   ** (with a leading zero if necessary) indicating the number of full hours
   ** to have passed since midnight and mm is a two-digit numeral
   ** (with leading zero if necessary) indicating the number of full minutes
   ** to have passed since the beginning of the current hour.
   ** (E.g., 3:27PM is "15:27", 12:08AM is "00:08").
   */
   public String toString24Format() {
      return "???";  // STUB
   }

   /* Reports whether or not this time of day falls earlier in the day
   ** than does the time of day represented by (formal parameter) t.
   */
   public boolean isEarlierThan(TimeOfDay t) {
      return true;   // STUB
   }
   

   // mutators
   // --------

   /* Sets this time of day to that described by the three parameters.
   ** precondition: 1 <= h <= HOURS_PER_HALF_DAY && 0 <= m < MINUTES_PER_HOUR
   */
   public void setTo(int h, int m, boolean isAM) {
      // STUB
   }

   /* Advances this time of day by one minute (possibly rolling over into
   ** the following day).
   */
   public void goForwardByMinute() {
      // INCORRECT when rolling over from one day to the next!!
      minutesSinceMidnight = minutesSinceMidnight + 1;
   }

   /* Advances this time of day by one hour (possibly rolling over into
   ** the following day).
   */
   public void goForwardByHour() {
      // INCORRECT when rolling over from one day to the next!!
      minutesSinceMidnight = minutesSinceMidnight + MINUTES_PER_HOUR;
   }

   /* Backs up this time of day by one minute (possibly rolling over into
   ** the previous day).
   */
   public void goBackwardsByMinute() {
      // INCORRECT when rolling over from one day to the previous day!!
      minutesSinceMidnight = minutesSinceMidnight - 1;
   }

   /* Backs up this time of day by one hour (possibly rolling over into
   ** the previous day).
   */
   public void goBackwardsByHour() {
      // INCORRECT when rolling over from one day to the previous day!!
      minutesSinceMidnight = minutesSinceMidnight - MINUTES_PER_HOUR;
   }

}