Flatten a directory structure and its hierarchy. This script moves every file in a subfolder to its parent and then delete the subfolder

flatten.rb

# frozen_string_literal: true

# Put me in a folder where you want to get rid of all the subfolders
# Run: ruby flatten.rb

def move_and_delete(dir)
  puts "Cleaning \"#{dir}\""

  Dir.foreach(dir) do |file|
    next if ['.', '..'].include?(file)

    source = File.join(dir, file)
    parent_path = File.dirname(dir)
    target = File.join(parent_path, file)

    if Dir.exist?(source)
      puts "\"#{source}\" is a folder, emptying it"
      move_and_delete(source)
    elsif File.file?(source)
      File.rename(source, target)
      puts "Moved \"#{file}\" to \"#{File.dirname(dir)}\""
    end
  end

  return move_and_delete(dir) unless Dir.empty?(dir)

  Dir.rmdir(dir)
  puts "Deleted directory: \"#{dir}\""
end

current_dir = ARGV.empty? ? Dir.pwd : File.expand_path(ARGV[0])
puts "Flattening all subdirectories in folder \"#{current_dir}\""
print 'Press any key to continue'
STDIN.gets.chomp

Dir.foreach(current_dir) do |entry|
  next if ['.', '..'].include?(entry)

  full_path = File.join(current_dir, entry)
  move_and_delete(full_path) if File.directory?(full_path)
end