/* TimeOfDay.java
** An instance of this class represents a time of day, precise to a minute.
** 
** Authors: R. McCloskey
** Known Defects: ...
*/

public class TimeOfDay {

   // 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.

   private int hour;    // class invariant: 0 <= hour < 24
   private int minute;  // class invariant: 0 <= minute < 60


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

   /* Initializes this time of day to that described by the three
   ** parameters, which are assumed to express the time in the traditional
   ** 12-hour mode.  An exception is thrown if 'h' is outside the range
   ** [1..12] or if 'm' is outside the range [0..60).
   */
   public TimeOfDay(int h, int m, boolean isPM) {
      // Verify that the parameters have values within the respective
      // valid ranges; if not, throw an exception.
      if (h < 1  ||  h > 12) {
         throw new IllegalArgumentException(h + " is not a legal hour value");
      }
      if (m < 0  ||  h >= 60) {
         throw new IllegalArgumentException(m + " is not a legal minute value");
      }

      this.minute = m;
      this.hour = from12To24(h, isPM);
   }


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

   /* Returns a string describing this time of day, in the traditional
   ** 12-hour (AM/PM) mode/format.  Examples: "5:37am", "12:04pm".
   */
   public String toString() {
      String hourStr, minuteStr, amPmStr;

      if (minute < 10)
         { minuteStr = "0" + minute; }
      else 
         { minuteStr = "" + minute; }

      if (hour < 12)
         { amPmStr = "am"; }
      else
         { amPmStr = "pm"; }

      hourStr = "" + from24To12(this.hour);

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

   /* Returns a string describing this time of day, in the 24-hour mode,
   ** which has this form:  hh:mm.
   ** Examples: "05:37", "12:04".
   */
   public String toString24() {
      return "hh:mm";   // STUB
   }

   /* 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 {
         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 true;   // STUB
   }


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

   /* Advances this time of day by a single minute, possibly resulting
   ** in it becoming the first minute of the following day.
   */
   public void advanceOneMinute() {
      minute = (minute + 1) % 60;
      if (minute == 0) {
         hour = (hour + 1) % 24;
      }
   }

   /* 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
   }


   /* Sets the "display mode" of this time of day to 24-hour mode, so
   ** that the toString() method will yield a string of the form hh:mm.
   */
   public void setTo24Mode() {
      // STUB
   }

   /* Sets the "display mode" of this time of day to 12-hour mode, so
   ** that the toString() method will yield a string of the traditional
   ** 12-hour mode form (e.g., "8:05pm", "11:37am").
   */
   public void setTo12Mode() { 
      // STUB
   }



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

   /* Translates the given 24-hour mode hour value into the corresponding
   ** 12-hour mode hour value.  E.g., 15 translates to 3 because 15 hours
   ** past midnight corresponds to the 3pm hour.
   ** 
   ** pre: 0 <= h < 24
   */
   private int from24To12(int h) {
      int result;
      if (h == 0)
         { result = 12; }
      else if (h <= 12)
         { result = h; }
      else 
         { result = h - 12; }

      return result;
   }

   /* Translates the given 12-mode hour value into the corresponding
   ** 24-mode hour value.  E.g., 3pm translates to 15 because the 3pm
   ** hour is 15 complete hours past midnight.
   ** 
   ** pre: 1 <= h <= 12 
   */
   private int from12To24(int h, boolean isPM) {
      int result;
      if (isPM) {
         if (h == 12) { result = 12; }
         else { result = h + 12; }
      }
      else {  // !isPM
         if (h == 12) { result = 0; }
         else { result = h; }
      }

      return result;
   }

}