/* An instance of this class represents a time of day, precise to a
** particular minute.
*/
public class TimeOfDay {

   // symbolic constants
   // ------------------
   private static final int HOURS_PER_DAY = 24;
   private static final int MINUTES_PER_HOUR = 60;


   // instance variables
   // ------------------
   private int hour;   // # of full hours since midnight
   private int minute; // # of full minutes since beginning of current hour

   // class invariants: 
   //    0 <= hour < HOURS_PER_DAY
   //    0 <= minute < MINUTES_PER_HOUR


   // constructor
   // -----------

   /* Initializes this object to the specified hour and minute.
   ** pre-condition: 0 <= h < HOURS_PER_DAY  &&  0 <= m < MINUTES_PER_HOUR
   */
   public TimeOfDay(int h, int m) { 
      this.setTo(h,m);
      //hours = h;  minute = m;
   }


   // observers/queries
   // ------------------

   /* With respect to this time of day, returns the number of full hours
   ** that have passed since midnight.
   */
   public int hourOf() { return this.hour; }

   /* With respect to this time of day, returns the number of full minutes
   ** that have passed since the beginning of the current hour.
   */
   public int minuteOf() { return this.minute;  }


   /* Returns true iff this time of day is earlier in the day than is the
   ** given time of day (t).
   */
   public boolean isEarlierThan(TimeOfDay t) { 
      return this.compareTo(t) < 0;
   }

   /* Returns:
   ** --a negative number if THIS time of day is earlier in the day than t
   ** --zero if THIS and t are the same time of day
   ** --a positive number if THIS time of day is later in the day than t
   */
   public int compareTo(TimeOfDay t) {
      if (this.hour < t.hour) { return -1; }
      else if (this.hour > t.hour) { return 1; }
      else {  // this.hour == t.hour
         if (this.minute < t.minute) { return -1; }
         else if (this.minute > t.minute) { return 1; }
         else { return 0; }
      }
      // alernative method body:
      // int hourDiff = this.hour - t.hour;
      // if (hourDiff != 0) { return hourDiff; }
      // else { return this.minute - t.minute; }
   }

   /* Returns a string describing this time of day in 12-hour mode.
   ** Examples: "5:16AM", "12:05PM"
   */
   public String toString() {    
      if (this.hour == 0) {
         return "12:" + minute + "AM";
      }
      else if (0 < this.hour  &&  hour < 12) {
         return hour + ":" + minute + "AM";
      }
      else if (this.hour == 12) {
         return "12:" + minute + "PM";
      }
      else { // hour is in range 13..23
         return (hour - 12) + ":" + minute + "PM";
      }
   }


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

   /* Sets this time of day to that specified, where h indicates
   ** hours since midnight and m indicates minutes since the
   ** beginning of the current hour.
   ** pre-condition: 0 <= h < HOURS_PER_DAY  &&  0 <= h < MINUTES_PER_HOUR
   ** exception: ???
   */
   public void setTo(int h, int m) {
      this.hour = h;   this.minute = m;
   }

   /* Moves this time of day forward by one minute.  Note that going
   ** forward from 11:59pm results in "wrapping around" to the first
   ** minute of the next day, midnight (12:00am).
   */
   public void goForwardByOneMinute() {
      if (hour+1 == HOURS_PER_DAY  &&  minute+1 == MINUTES_PER_HOUR) {
         //hour = 0; minute = 0;
         setTo(0,0);
      }
      else {  // time is not 11:59pm
         if (minute+1 == MINUTES_PER_HOUR) {
            //minute = 0; hour = hour+1;
            setTo(hour+1, 0);
         }
         else {  // "normal" case (i.e., no wraparound occurs)
            //minute = minute + 1;
            setTo(hour, minute+1);
         }
      }
   } 

   /* Moves this time of day backward by one minute.  Note that going
   ** backwards from midnight (12:00am) results in "wrapping around" 
   ** the last minute of the previous day (11:59pm).
   */
   public void goBackwardByOneMinute() {


   } 

}