import java.text.DecimalFormat;

/** Class to represent a time of day.
*/
public class Time {

   // These are class-wide (shared) data members. 
   // Checkstyle requires us to declare them before the instance data.
   
   /** Format integer with 4 digits of precision. */
   private static DecimalFormat four0s = new DecimalFormat("0000");
   /** Format integer with 2 digits of precision. */
   private static DecimalFormat two0s = new DecimalFormat("00");
   
   // These are handy constants.
   
   /** Number of hours in half day. */
   private static final int HALFDAY = 12;
   /** Divisor for miliarty time computations. */
   private static final int DIVISOR = 100;
   /** Number of minutes in a day. */
   private static final int DAYMINS = 60;
         
         
   // These are the instance data members.
   // Checkstyle requires us to document each one.
    
   /** Hour in the day, in military format: 0-23 valid. */
   private int hours; 
   /** Minutes in the day, 0-59 valid. */
   private int mins;   
    
   /** Create a time object from a string, such as "2:04pm".
       @param tstr the time string, such as "12:14am"
   */
   public Time(String tstr) {
      int i = tstr.indexOf(':');
      String hrs = tstr.substring(0, i);
      tstr = tstr.substring(i + 1);
      String mns = tstr.substring(0, 2);
      char when = tstr.toLowerCase().charAt(2);  // 'a' or 'p'
      this.setHours(Integer.parseInt(hrs));
      this.setMins(Integer.parseInt(mns));
      if (when == 'a' && this.hours == HALFDAY) {
         this.hours = 0;  // midnight
      }
      if (when == 'p' && this.hours < HALFDAY) {
         this.hours = this.hours + HALFDAY;
      }
   }
   
   /** Create a time object from an integer, military style.
       @param mil the military time integer, such as 1445
   */
   public Time(int mil) {
      this.setHours(mil / DIVISOR);
      this.setMins(mil % DIVISOR);
   }
   
   /** Set the hours to a new value.
       @param hr the hours to use, must be 0 <= hr <= 23
   */
   public void setHours(int hr) {
      if (hr < 0 || hr >= 2 * HALFDAY) {
         hr = 0;
      }
      this.hours = hr;
   }

   /** Set the minutes to a new value.
       @param mns the minutes to use, must be 0 <= mins <= 59
   */   
   public void setMins(int mns) {
      if (mns < 0 || mns >= DAYMINS) {
         this.mins = 0;
      }
      this.mins = mns;
   }
   
   /** Get a string representation, in standard format.
       @return the string, such as "2:45pm"
   */
   public String toString() {
      String tstr = "";
      char when = 'a';
      if (this.hours >= HALFDAY) {
         when = 'p';
      }
      if (this.hours == 0) {
         tstr += HALFDAY;
      }
      else if (this.hours > HALFDAY) {
         tstr += this.hours - HALFDAY;
      }
      else {
         tstr += this.hours;
      }
      tstr += ":" + two0s.format(this.mins) + when + 'm';
      return tstr;
   }
   
   /** Get a military string representation.
       @return the string, such as "0405"
   */
   public String military() { 
      return four0s.format(this.hours * DIVISOR + this.mins);
   }
}