require 'uri'
require 'net/ssh/proxy/command'

module Net; module SSH; module Proxy

  # An implementation of a jump proxy. To use it, instantiate it,
  # then pass the instantiated object via the :proxy key to
  # Net::SSH.start:
  #
  #   require 'net/ssh/proxy/jump'
  #
  #   proxy = Net::SSH::Proxy::Jump.new('user@proxy')
  #   Net::SSH.start('host', 'user', :proxy => proxy) do |ssh|
  #     ...
  #   end
  class Jump < Command

    # The jump proxies
    attr_reader :jump_proxies

    # Create a new socket factory that tunnels via multiple jump proxes as
    # [user@]host[:port].
    def initialize(jump_proxies)
      @jump_proxies = jump_proxies
    end

    # Return a new socket connected to the given host and port via the jump
    # proxy that was requested when the socket factory was instantiated.
    def open(host, port, connection_options = nil)
      build_proxy_command_equivalent(connection_options)
      super
    end

    # We cannot build the ProxyCommand template until we know if the :config
    # option was specified during `Net::SSH.start`.
    def build_proxy_command_equivalent(connection_options = nil)
      first_jump, extra_jumps = jump_proxies.split(",", 2)
      config = connection_options && connection_options[:config]
      uri = URI.parse("ssh://#{first_jump}")

      template = "ssh"
      template << " -l #{uri.user}"    if uri.user
      template << " -p #{uri.port}"    if uri.port
      template << " -J #{extra_jumps}" if extra_jumps
      template << " -F #{config}" if config != true && config
      template << " -W %h:%p "
      template << uri.host

      @command_line_template = template
    end
  end

end; end; end