Sinatra local directory server

server.rb

require 'sinatra'

$pwd = ENV['PWD']

configure do
  set :server, :puma
  set :root, File.dirname(__FILE__)
  set :port, 7777
end


get '/' do
 @files = Dir.entries($pwd)
 erb :index
end

get '/*' do
 files = params['splat'].join("")
 if Dir.exists?(files)
  @dir = "/" + files
  @files = Dir.entries($pwd + '/' + files)
  erb :index
 else
   send_file files
 end
end

__END__

@@ index
<% @files.each do |file| %>
  <a href="<%= @dir %>/<%=file %>"><%=file %></a><br>
<% end %>