# This is a comment and will not be executed 
 # by the Ruby interpreter.
 #
 # This is not the usual 'Hello World' example, so 
 # don't worry if you don't understand everything. 
 # This example is meant to give you a general feeling 
 # of what it is like to write Ruby programs.
 
 require 'pathname'   # Here we're requiring an external library
                     # which is part of the Ruby Standard Library.

class FilePrinter

  # Constructor method
  def initialize(path)
    # This method expects a valid path, however Ruby is dynamically-typed
    # so anything can be passed to this method.
    # To check that the input value is valid, just check if if it behaves
    # like a path. This is called 'duck typing'.
    raise RuntimeError, "Invalid path: #{path}" unless path.respond_to? :basename
    @path = path
    @name = @path.basename
  end

  def show
    # Ruby objects and expressions can be interpolated in strings
    puts "  #@name -- #{@path.stat.size} bytes"
  end

end

class DirPrinter < FilePrinter # Definition of a child class

  def initialize(path)
    super # Call to the parent's constructur
    @children = @path.children
  end

  def show
    puts "  #@name/ -- #{@children.length} item(s)"
  end

end

# No parenthesis are required unless needed!
pwd = Pathname.new Dir.pwd

puts "Current Directory: #{pwd}"

# Get the children items of the current directory, 
# select only directories, 
# sort them alphabetically,
# and for each one of them...
pwd.children.select{|i| i.directory? }.sort.each do |item|
  # Call the show method, printing the 
  # directory name and the number of child items
  DirPrinter.new(item).show
end

pwd.children.select{|i| !i.directory? }.sort.each do |item|
  FilePrinter.new(item).show
end