//  Times.swift  Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2014-10-10  File created.
//  2016-11-09  Last modification.

//  This program demonstrates:
//     - inheritance and overriding of methods
//     - how to get the current system time

import Foundation

//  Swift does not have abstract classes, i.e., classes that would
//  have methods without implementation. The following class is
//  a kind of imitation of an abstract class, as it should be used
//  only as a superclass for other classes.

class CurrentTime
{
   var current_hours : Int = 0 
   var current_minutes : Int = 0
   var current_seconds : Int = 0

   init()
   {
      // This initializer reads the current computer time

      let current_date = Date()
      let calendar = Calendar.current

      current_hours = calendar.component( Calendar.Component.hour,
                                          from: current_date )
                                           
      current_minutes = calendar.component( Calendar.Component.minute,
                                            from: current_date )
                                           
      current_seconds = calendar.component( Calendar.Component.second,
                                            from: current_date )
   }

   func print_time()
   {
      print( "\n Objects of class CurrentTime should not be created.\n")
   }
}

//  It is not entirely true that the 12-hour a.m./p.m. time
//  would be used everywhere in America, and the 24-hour time
//  would be used everywhere in Europe. The names AmericanTime
//  and EuropeanTime just happen to be nice names to
//  distinguish these two different ways to display time.

class  AmericanTime  :  CurrentTime
{
   override func print_time()
   {
      let  american_hours  =

        [ 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
          12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11  ]

      print( String( format: "%d:%02d:%02d", american_hours[ current_hours ],
                             current_minutes, current_seconds ), terminator: "" )

      if  current_hours  <  12
      {
         print( " a.m." )
      }
      else
      {
         print( " p.m." )
      }
   }
}

class  EuropeanTime  :  CurrentTime
{
   override func print_time()
   {
      print( String( format: "%d:%02d:%02d", current_hours,
                             current_minutes, current_seconds ) )
   }
}


//  Here begins the main program.
//  time_to_show will refer either to an EuropeanTime object or to
//  an AmericanTime object, depending on what the user wants to see.

var time_to_show : CurrentTime 

print( "\n Type 12 to see the time in 12-hour a.m./p.m format."
    +  "\n Any other number gives the 24-hour format. ", terminator: "" )

let user_response  =  Int( readLine()! )!

if  user_response  ==  12
{
   time_to_show  =  AmericanTime()
}
else
{
   time_to_show  =  EuropeanTime()
}

print( "\n  The time is now ", terminator: "" )

time_to_show.print_time()

print( "\n" )