//  MonthCalendars.kt  Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2024-01-20  File created.

/*  This program can print month calendars to a Terminal or
    Command Prompt window. There is a menu through which you
    can select printing operations.
    
    Standard class LocalDate is used to handle date information.
    
    Class EnglishCalendar is marked 'open' so that a new
    class can be derived from it.
*/

import java.time.LocalDate
import java.time.temporal.WeekFields


open class EnglishCalendar( var this_year : Int,
                            var this_month : Int )
{
   var names_of_months  =

      arrayOf( "January", "February", "March", "April", "May", "June",
               "July", "August", "September", "October", "November",
               "December" )
               
   var  week_description  =  " Week   Mon  Tue  Wed  Thu  Fri  Sat  Sun"

   fun get_calendar_year() : Int
   {
      return this_year
   }

   fun get_calendar_month() : Int
   {
      return this_month
   }


   fun increment_calendar_month()
   {
      this_month ++ 

      if ( this_month > 12 )
      {
         this_month = 1 
         this_year ++ 
      }
   }

   fun print()
   {
      var a_day_in_this_month = LocalDate.of( this_year, this_month, 1 ) ;

      // Days of week are numbered from 1 to 7.
      // The first day of week is Monday.

      var day_of_week_value = 1 

      var day_of_week_of_first_day  =
                          a_day_in_this_month.getDayOfWeek().getValue()

      print( "\n\n   "  +  names_of_months[ this_month - 1 ]
           +  "  "  +  this_year  +  "\n\n"  +  week_description   +  "\n\n" )

      print( String.format( "%4d  ",  a_day_in_this_month.get( 
                                      WeekFields.ISO.weekOfWeekBasedYear() ) ) )

      // The first week of a month is often an incomplete week, 
      // i.e., the first part of week belongs to the previous
      // month. In place of the days that belong to the previous
      // month we print just spaces.

      while ( day_of_week_value != day_of_week_of_first_day )
      {
         print( "     " ) 
         day_of_week_value  ++
      }

      while ( this_month  ==  a_day_in_this_month.getMonthValue() )
      {
         if ( day_of_week_value  >=  8 )
         {
            print( String.format( "\n%4d  ",
                               a_day_in_this_month.get(  
                                      WeekFields.ISO.weekOfWeekBasedYear() ) ) )

            day_of_week_value  =  1 
         }

         print( String.format( "%5d", a_day_in_this_month.getDayOfMonth() ) )

         a_day_in_this_month = a_day_in_this_month.plusDays( 1 )

         day_of_week_value  ++ 
      }

      System.out.print( "\n" )
   }
}

// SpanishCalendar will inherit from EnglishCalendar.

class SpanishCalendar( given_year : Int, given_month : Int ) 

        : EnglishCalendar( given_year, given_month )
{
   init
   {
      names_of_months = 

         arrayOf( "Enero", "Febrero", "Marzo", "Abril",
                  "Mayo", "Junio", "Julio", "Agosto",
                  "Septiembre", "Octubre", "Noviembre", "Diciembre" )

      week_description = "Semana  Lun  Mar  Mie  Jue  Vie  Sab  Dom" 
      
   }
}

fun main()
{
   val a_spanish_calendar = SpanishCalendar( 2023, 12 )

   a_spanish_calendar.print()

   var calendar_to_print = EnglishCalendar( 2024, 1 )

   calendar_to_print.print()

   var user_selection  =  "????" 

   print( "\n This program prints calendars. Please, select from"
       +  "\n the following menu by typing in a letter. " ) 

   while ( user_selection[ 0 ]  !=  'e' )
   {
      print( "\n\n   p   Print current calendar."
            +  "\n   n   Print next calendar."
            +  "\n   s   Switch to Spanish calendars."
            +  "\n   e   Exit the program.\n\n   " ) 

      user_selection  =  readLine()!!

      if ( user_selection[ 0 ]  ==  'p' )
      {
         calendar_to_print.print()
      }
      else if ( user_selection[ 0 ]  ==  'n' )
      {
         calendar_to_print.increment_calendar_month()

         calendar_to_print.print()
      }
      else if ( user_selection[ 0 ]  ==  's' )
      {
         // We'll take the calendar year and month from the old calendar
         // object and use them to create a SpanishCalendar object.

         calendar_to_print =
              SpanishCalendar( calendar_to_print.get_calendar_year(),
                               calendar_to_print.get_calendar_month() )

         calendar_to_print.print()
      }
   }
}