//  ImportantBirthdays.swift  Copyright (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2015-10-08  File created.
//  2016-11-09  Last modification.

//  This program demonstrates:
//    - use of standard types Date, Calendar, etc.

import Foundation

// The following extension to Date was written based on
// the advice in address
// http://stackoverflow.com/questions/24089999/how-do-you-create-a-swift-date-object

extension Date
{
   init( _ date_as_string: String )
   {
      let date_formatter = DateFormatter()
      date_formatter.dateFormat = "yyyy-MM-dd"
      date_formatter.locale = Locale( identifier: "en_US_POSIX" )
      let date_object = date_formatter.date( from: date_as_string )!
      self.init( timeInterval: 0, since: date_object )
   }
}


let calendar = Calendar.current

print( "\n Type in your date of birth as YYYY-MM-DD"
    +  "\n Use four digits for the year and two digits"
    +  "\n for the month and day:  ", terminator: "" )

let date_of_birth_as_string = readLine()!

let date_of_birth = Date( date_of_birth_as_string )

let day_of_week_of_birthday  = calendar.component( Calendar.Component.weekday,
                                                   from: date_of_birth )
let date_formatter = DateFormatter()

print( "\n You were born on a "
    +  date_formatter.weekdaySymbols[ day_of_week_of_birthday - 1 ]  )
print( " Here are your days to celebrate. You are \n" )

let year_of_birthday = calendar.component( Calendar.Component.year,
                                           from: date_of_birth )

let month_of_birthday = calendar.component( Calendar.Component.month,
                                            from: date_of_birth )

let day_of_birthday = calendar.component( Calendar.Component.day,
                                          from: date_of_birth )

var years_to_celebrate  =  10 

while  years_to_celebrate  <  80
{
   var celebration_day_components = DateComponents()
   celebration_day_components.year = year_of_birthday + years_to_celebrate
   celebration_day_components.month = month_of_birthday
   celebration_day_components.day = day_of_birthday
   celebration_day_components.hour = 14  // Two o'clock in the afternoon.

   let date_to_celebrate = calendar.date( from: celebration_day_components )!

   print( String( format: "   %d years old on %04d-%02d-%02d (",
                  years_to_celebrate, year_of_birthday + years_to_celebrate,
                  month_of_birthday, day_of_birthday ), terminator: ""  )

   let day_of_week_of_celebration_date  =
                            calendar.component( Calendar.Component.weekday,
                                                from: date_to_celebrate )

   print( date_formatter.weekdaySymbols[ day_of_week_of_celebration_date - 1 ]
          + ")" )

   years_to_celebrate  =  years_to_celebrate  +  10 
}

print( "\n" )