/* TimeOfDay.java
** An instance of this class represents a time of day, precise to a minute.
** 
** Authors: R. McCloskey and < STUDENT's NAME >
** Collaborated with: ...
** Known Defects: ...
*/

public class TimeOfDay {

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

   public static final int MINUTES_PER_HOUR = 60;
   public static final int HOURS_PER_DAY = 24;

   // instance variables
   // ------------------

   // A time of day is represented by the pair (hour, minute) of integers,
   // where the value of 'hour' is the number of complete hours since midnight
   // and the value of 'minute' is the number of complete minutes since the
   // beginning of the current hour.

   protected int hour;    // class invariant: 0 <= hour < HOURS_PER_DAY
   protected int minute;  // class invariant: 0 <= minute < MINUTES_PER_HOUR


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

   /* Initializes this time of day to midnight.
   */
   public TimeOfDay() { setTo(0,0); }

   /* Initializes this time of day to that described by the two parameters,
   ** which indicate, respectively, the number of complete hours since
   ** midnight and the number of minutes since the beginning of the current
   ** hour.  
   ** An exception is thrown if 'h' is outside the range [0..HOURS_PER_DAY)
   ** or if 'm' is outside the range [0..MINUTES_PER_HOUR).
   */
   public TimeOfDay(int h, int m) { setTo(h, m); }


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

   /* Returns a string describing this time of day (e.g., "15:07", "09:45").
   */
   @Override
   public String toString() {
      return toTwoDigits(hour) + ":" + toTwoDigits(minute);
   }


   /* Reports whether or not this time of day and the given one represent
   ** the same minute of a day.
   */
   public boolean equals(TimeOfDay t) {
      return this.hour == t.hour  &&  this.minute == t.minute;
   }

   /* Reports whether or not this time of day occurs earlier in the day
   ** than the given time of day (t).
   */
   public boolean isEarlierThan(TimeOfDay t) {
      boolean result;
      if (this.hour != t.hour) { 
         result = this.hour < t.hour; 
      }
      else {   // this and t are in same hour of day
         result = this.minute < t.minute;
      }
      return result;
   }
   //Note: The statement 'result = this.hour < t.hour'
   //      is equivalent to this inferior way of saying the same thing:
   //
   //         if (this.hour < t.hour) { result = true; }
   //         else { result = false; }
   // 
   //      A similar remark applies to 'result = this.minute < t.minute'.
   

   /* Reports whether or not this time of day occurs between the given
   ** times 'start' and 'stop'.  To illustrate, consider these examples
   ** and take particular note of those in which 'start' is later in the 
   ** day than is 'stop'.
   **
   **            this     start      stop     result
   **          -------   -------   -------    ------
   **          10:37am    9:15am    2:40pm     true
   **           6:37pm    9:15am    2:40pm     false
   **           8:23am    9:15pm   10:35am     true
   **          12:02pm    9:15pm   10:35am     false
   */
   public boolean isBetween(TimeOfDay start, TimeOfDay stop) {
      return false;   // STUB!
   }


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

   /* Sets this time of day to that described by the two parameters, which
   ** indicate, respectively, the number of complete hours since midnight 
   ** and the number of minutes since the beginning of the current hour.  
   ** An exception is thrown if 'h' is outside the range [0..HOURS_PER_DAY)
   ** or if 'm' is outside the range [0..MINUTES_PER_HOUR).
   */
   public void setTo(int h, int m) {
      // Verify that the parameters have values within the respective
      // valid ranges; if not, throw an exception.
      if (h < 0  ||  h >= HOURS_PER_DAY) {
         throw new IllegalArgumentException(h + " is not a legal hour value");
      }
      if (m < 0  ||  h >= MINUTES_PER_HOUR) {
         throw new IllegalArgumentException(m + " is not a legal minute value");
      }

      // If the parameters are within the valid ranges, set them to the
      // specified values.
      this.hour = h;
      this.minute = m;
   }

   /* Changes this time of day by the specified number of minutes.
   ** A positive value means that the time is moved forward by that
   ** many minutes, which could advance it one or more days into the
   ** future.  A negative value means that the time is moved backward,
   ** which could place it one or more days in the past.
   */
   public void changeByMinutes(int mDelta) {
      final int MINUTES_PER_DAY = MINUTES_PER_HOUR * HOURS_PER_DAY;

      // STUB!
   }

   /* Changes this time of day by the specified number of hours.
   ** A positive value means that the time is moved forward by that
   ** many hours, which could advance it one or more days into the
   ** future.  A negative value means that the time is moved backward,
   ** which could place it one or more days in the past.
   */
   public void changeByHours(int hDelta) {
      // STUB!
   }


   /* Advances this time of day by a single minute, possibly resulting
   ** in it becoming the first minute of the following day.
   */
   public void advanceOneMinute() { 
      // STUB!
   }

   /* Retreats this time of day by a single minute, possibly resulting
   ** in it becoming the last minute of the preceding day.
   */
   public void retreatOneMinute() {
      // STUB!
   }



   // utilities
   // ---------


   /* Returns the String image of the given int value, with a 
   ** leading zero if its image is of length one.
   ** E.g., 5 --> "05", 21 --> "21".
   */
   protected String toTwoDigits(int k) { 
      if (k < 10) { return "0" + k; }
      else { return "" + k; }
   }

}