Copy files from a nested structure to a flat structure while preserving naming

flat_rename.rb

#!/usr/bin/env ruby

require 'fileutils'

def create_filename(item, source, separator)
  parents = File.dirname(item).split('/').last(2)
  root = source.split('/').last

  name = parents.first == root ? parents.last : parents.join(separator)
  name += separator + File.basename(item)
end

def create_pattern(file_type)
  file_type == '' ? '*.{jpg,png}' : "*.{#{file_type}}"
end

def empty_destination(destination)
  FileUtils.rm_rf(Dir["#{destination}/*"])
end

def get_input(msg)
  puts msg
  STDIN.gets.strip
end

def help_prompt(args)
  if (args.first == '--help' || args.count != 2)
    puts "Usage: #{__FILE__} [source] [destination]\n"
    exit
  end
end

help_prompt(ARGV)

VALID_INPUT = %w(y yes)

# Getting source and destination from the shell so that I get
# auto completion and path expansion
# e.g. ~/Desktop -> /Users/me/Desktop
SOURCE      = ARGV[0]
DESTINATION = ARGV[1]

# For all other input prompt to make it easier to use
empty        = get_input "Do you want to empty '#{DESTINATION}'? (n)"
file_type    = get_input("\nWhat kind of files do you want? (jpg png)").gsub(/\s+/, ',')
separator    = get_input "\nHow would you like to separate words? ()"
glob_pattern = create_pattern(file_type)

empty_destination DESTINATION if VALID_INPUT.include? empty.downcase

Dir.glob("#{SOURCE}/**/#{glob_pattern}").each do |item|
  name = create_filename(item, SOURCE, separator)

  FileUtils.cp(item, "#{DESTINATION}/#{name}")
end