Without using any date/time library, write a function or method that accepts two mandatory arguments. The first argument is a string of the format[H]H:MM {AM|PM} and the second argument is an integer. Assume the integer is the number of minutes to add to the string. The return value of the function should be a string of the same format as the fi…

people_test.rb

#! /usr/bin/env ruby

# Without using any date/time library, write a function or method that accepts
# two mandatory arguments. The first argument is a string of the format[H]H:MM
# {AM|PM} and the second argument is an integer. Assume the integer is the
# number of minutes to add to the string. The return value of the function
# should be a string of the same format as the first argument. For example
# add_minutes('9:13 AM', 10) would return 9:23 AM.

# To run:
# $ ruby peoples_test.rb <string="9:45 PM"> <int=60>


def format_time(hours,minutes,period)
  return "#{hours}:#{minutes} #{period}"
end

def add_minutes (time, append = 0)
  # check time formatting
  unless /^(?<hours>[0-9]{1,2}):(?<minutes>[0-9]{2})\s(?<period>(AM|PM))$/i =~ time
    raise ArgumentError, 'First argument: time (string) is invalid. (Inproper date format)'
  end
  # check that hours is proper format
  if hours.to_i > 12
    raise ArgumentError, 'First argument: time (string) is invalid. (Inproper date format)'
  end
  # check minutes is integer
  unless append.is_a? Integer
    raise ArgumentError, 'Second argument: minutes (int) is invalid.'
  end
  # Evaluate input time
  output       = ""
  hours        = hours.to_i
  minutes      = minutes.to_i
  period       = period.upcase
  long_hours   = (hours % 12) + (period == 'AM' ? 0 : 12)       # Convert 12 hour format to 24 hour format
  
  return format_time(hours,minutes+append,period) if (minutes + append) <= 59
  
  more_hours   = (minutes + append) / 60                        # retrieve leftover hours
  more_minutes = (minutes + append) % 60                        # retreive leftover minutes
  mod_hours    = (long_hours + more_hours) % 24                 # combine leftover hours and maintain 24 hour format
  period       = (mod_hours > 11 ? "PM" : "AM")                 # convert period based on long hour
  short_hours  = ((mod_hours % 12) > 0 ? (mod_hours % 12) : 12) # convert to 12 hour format
  
  return format_time(short_hours, more_minutes, period)
end

input_time    = ARGV[0]
input_minutes = ARGV[1]

print "#{add_minutes input_time, input_minutes.to_i}\n"