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# -*- coding: utf-8 -*-
#!/usr/bin/env ruby
 
require 'faker'
require 'optparse'
require 'ostruct'
 
module Options
  VERSION = [0, 1]
 
  def self.parse(args)
    options = OpenStruct.new num_samples: 1000, generate: false
 
    opts = OptionParser.new do |op|
      op.version = VERSION
      op.banner = "Usage: #{op.program_name} [OPTION] FILE"
      op.separator """Display unique students listed in FILE. If `--generate' switch is given,
write sample students to FILE instead.
 
"""
 
      op.on("-n", "--num-samples NUMBER", Integer,
         "Number of samples to generate (default 1000)",
         "Ignored unless `--generate' is given") do |num|
        options.num_samples = num
      end
 
      op.on("--generate", "Generate sample file rather then read it") do
        options.generate = true
      end
 
      op.on_tail("-h", "--help", "Show this message and exit") do
        puts opts
        exit
      end
 
      op.on_tail("-v", "--version", "Show version information and exit") do
        puts op.version.join('.')
        exit
      end
    end
    opts.parse! args
 
    raise "Missing filename (use `--help' for help)" unless args.size == 1
 
    options.file = args.first
    options
  end
end
 
module Students
  GENDER = ["male", "female"]
  AGE = (17..70).to_a
  COURSE = (1..5).to_a
  UNIQUE_RATIO = 0.8
 
  def self.generate(num_samples)
    num_unique_names = (UNIQUE_RATIO * num_samples).to_i
    unique_names = Array.new(num_unique_names).collect { Faker::Name.last_name }
    Array.new(num_samples) do
      "#{unique_names.sample} #{GENDER.sample} #{AGE.sample} #{COURSE.sample}"
    end
  end
 
  def self.unique(file)
    file.readlines.uniq { |s| s.split.first }
  end
end
 
if $0 == __FILE__
  begin
    options = Options.parse ARGV
 
    if options.generate
      File.open(options.file, 'w') do |f|
        f.puts Students.generate(options.num_samples)
      end
    else
      File.open(options.file, "r") do |f|
        Students.unique(f).each do |s|
          printf "%-30s%-10s%-5s%-3s\n", *s.split
        end
      end
    end
  rescue StandardError => err
    abort err.to_s
  end
end