#!/usr/bin/env ruby
##Assignment 3
###Justin Beitz

def create_array(data)
  data.chomp.split(' ').map(&:to_i) # returns array of ints
end

def calc_average(data)
  data = (data.reduce(:+) / data.size.to_f).round(4)
end

def calc_standard_deviation(data)
  average = data.reduce(:+) / data.size.to_f
  sum = data.inject(0){|accum, i| accum +(i-average)**2 }
  s_deviation = sum/(data.length - 1).to_f
  s_deviation = Math.sqrt(s_deviation).round(4)
end

def calc_median(data)
    return nil if data.empty?
    data.sort!
    mid = (data.length-1) / 2.0
    (data[mid.floor] + data[mid.ceil]).fdiv(2)
end

def create_writefile(file, average, sd, median, data)
  File.open(ARGV[1], 'a') do |file|
    file.write("%-10s %-25s %-15s %-16s\n" % [average, sd, median, data])
  end
end

unless ARGV.size == 2
  STDERR.puts "Error: Incorrect number of arguements\n\nOK. Goodbye."
else
  puts "Processing: " + ARGV[0] + " (input), " + ARGV[1] + " (output)"
  row = 0
  # set command line argument1 and argument2 to in_file and out_file respectivley
  in_file = File.new(ARGV[0], 'r')
  out_file = File.new(ARGV[1], 'w')
 # out_file.puts "Average		Standard Deviation		Median		Data"
  out_file.puts " "
  in_file.each_line do |line|
    row = row + 1
    data = create_array(line)
    average = calc_average(data)
    s_deviation = calc_standard_deviation(data)
    median = calc_median(data)

  create_writefile(ARGV[1], average, s_deviation, median, data)
  end
  puts "Processing: Complete"
end