#
# = net/ftp.rb - FTP Client Library
#
# Written by Shugo Maeda <shugo@ruby-lang.org>.
#
# Documentation by Gavin Sinclair, sourced from "Programming Ruby" (Hunt/Thomas)
# and "Ruby In a Nutshell" (Matsumoto), used with permission.
#
# This library is distributed under the terms of the Ruby license.
# You can freely distribute/modify this library.
#
# It is included in the Ruby standard library.
#
# See the Net::FTP class for an overview.
#

require "socket"
require "monitor"

module Net

  # :stopdoc:
  class FTPError < StandardError; end
  class FTPReplyError < FTPError; end
  class FTPTempError < FTPError; end
  class FTPPermError < FTPError; end
  class FTPProtoError < FTPError; end
  class FTPConnectionError < FTPError; end
  # :startdoc:

  #
  # This class implements the File Transfer Protocol.  If you have used a
  # command-line FTP program, and are familiar with the commands, you will be
  # able to use this class easily.  Some extra features are included to take
  # advantage of Ruby's style and strengths.
  #
  # == Example
  #
  #   require 'net/ftp'
  #
  # === Example 1
  #
  #   ftp = Net::FTP.new('ftp.netlab.co.jp')
  #   ftp.login
  #   files = ftp.chdir('pub/lang/ruby/contrib')
  #   files = ftp.list('n*')
  #   ftp.getbinaryfile('nif.rb-0.91.gz', 'nif.gz', 1024)
  #   ftp.close
  #
  # === Example 2
  #
  #   Net::FTP.open('ftp.netlab.co.jp') do |ftp|
  #     ftp.login
  #     files = ftp.chdir('pub/lang/ruby/contrib')
  #     files = ftp.list('n*')
  #     ftp.getbinaryfile('nif.rb-0.91.gz', 'nif.gz', 1024)
  #   end
  #
  # == Major Methods
  #
  # The following are the methods most likely to be useful to users:
  # - FTP.open
  # - #getbinaryfile
  # - #gettextfile
  # - #putbinaryfile
  # - #puttextfile
  # - #chdir
  # - #nlst
  # - #size
  # - #rename
  # - #delete
  #
  class FTP
    include MonitorMixin

    # :stopdoc:
    FTP_PORT = 21
    CRLF = "\r\n"
    DEFAULT_BLOCKSIZE = 4096
    # :startdoc:

    # When +true+, transfers are performed in binary mode.  Default: +true+.
    attr_reader :binary

    # When +true+, the connection is in passive mode.  Default: +false+.
    attr_accessor :passive

    # When +true+, all traffic to and from the server is written
    # to +$stdout+.  Default: +false+.
    attr_accessor :debug_mode

    # Sets or retrieves the +resume+ status, which decides whether incomplete
    # transfers are resumed or restarted.  Default: +false+.
    attr_accessor :resume

    # The server's welcome message.
    attr_reader :welcome

    # The server's last response code.
    attr_reader :last_response_code
    alias lastresp last_response_code

    # The server's last response.
    attr_reader :last_response

    #
    # A synonym for <tt>FTP.new</tt>, but with a mandatory host parameter.
    #
    # If a block is given, it is passed the +FTP+ object, which will be closed
    # when the block finishes, or when an exception is raised.
    #
    def FTP.open(host, user = nil, passwd = nil, acct = nil)
      if block_given?
        ftp = new(host, user, passwd, acct)
        begin
          yield ftp
        ensure
          ftp.close
        end
      else
        new(host, user, passwd, acct)
      end
    end

    #
    # Creates and returns a new +FTP+ object. If a +host+ is given, a connection
    # is made. Additionally, if the +user+ is given, the given user name,
    # password, and (optionally) account are used to log in.  See #login.
    #
    def initialize(host = nil, user = nil, passwd = nil, acct = nil)
      super()
      @binary = true
      @passive = false
      @debug_mode = false
      @resume = false
      @sock = NullSocket.new
      @logged_in = false
      if host
        connect(host)
        if user
          login(user, passwd, acct)
        end
      end
    end

    # A setter to toggle transfers in binary mode.
    # +newmode+ is either +true+ or +false+
    def binary=(newmode)
      if newmode != @binary
        @binary = newmode
        send_type_command if @logged_in
      end
    end

    # Sends a command to destination host, with the current binary sendmode
    # type.
    #
    # If binary mode is +true+, then "TYPE I" (image) is sent, otherwise "TYPE
    # A" (ascii) is sent.
    def send_type_command # :nodoc:
      if @binary
        voidcmd("TYPE I")
      else
        voidcmd("TYPE A")
      end
    end
    private :send_type_command

    # Toggles transfers in binary mode and yields to a block.
    # This preserves your current binary send mode, but allows a temporary
    # transaction with binary sendmode of +newmode+.
    #
    # +newmode+ is either +true+ or +false+
    def with_binary(newmode) # :nodoc:
      oldmode = binary
      self.binary = newmode
      begin
        yield
      ensure
        self.binary = oldmode
      end
    end
    private :with_binary

    # Obsolete
    def return_code # :nodoc:
      $stderr.puts("warning: Net::FTP#return_code is obsolete and do nothing")
      return "\n"
    end

    # Obsolete
    def return_code=(s) # :nodoc:
      $stderr.puts("warning: Net::FTP#return_code= is obsolete and do nothing")
    end

    # Contructs a socket with +host+ and +port+.
    #
    # If SOCKSSocket is defined and the environment (ENV) defines
    # SOCKS_SERVER, then a SOCKSSocket is returned, else a TCPSocket is
    # returned.
    def open_socket(host, port) # :nodoc:
      if defined? SOCKSSocket and ENV["SOCKS_SERVER"]
        @passive = true
        return SOCKSSocket.open(host, port)
      else
        return TCPSocket.open(host, port)
      end
    end
    private :open_socket

    #
    # Establishes an FTP connection to host, optionally overriding the default
    # port. If the environment variable +SOCKS_SERVER+ is set, sets up the
    # connection through a SOCKS proxy. Raises an exception (typically
    # <tt>Errno::ECONNREFUSED</tt>) if the connection cannot be established.
    #
    def connect(host, port = FTP_PORT)
      if @debug_mode
        print "connect: ", host, ", ", port, "\n"
      end
      synchronize do
        @sock = open_socket(host, port)
        voidresp
      end
    end

    #
    # WRITEME or make private
    #
    def set_socket(sock, get_greeting = true)
      synchronize do
        @sock = sock
        if get_greeting
          voidresp
        end
      end
    end

    # If string +s+ includes the PASS command (password), then the contents of
    # the password are cleaned from the string using "*"
    def sanitize(s) # :nodoc:
      if s =~ /^PASS /i
        return s[0, 5] + "*" * (s.length - 5)
      else
        return s
      end
    end
    private :sanitize

    # Ensures that +line+ has a control return / line feed (CRLF) and writes
    # it to the socket.
    def putline(line) # :nodoc:
      if @debug_mode
        print "put: ", sanitize(line), "\n"
      end
      line = line + CRLF
      @sock.write(line)
    end
    private :putline

    # Reads a line from the sock.  If EOF, then it will raise EOFError
    def getline # :nodoc:
      line = @sock.readline # if get EOF, raise EOFError
      line.sub!(/(\r\n|\n|\r)\z/n, "")
      if @debug_mode
        print "get: ", sanitize(line), "\n"
      end
      return line
    end
    private :getline

    # Receive a section of lines until the response code's match.
    def getmultiline # :nodoc:
      line = getline
      buff = line
      if line[3] == ?-
          code = line[0, 3]
        begin
          line = getline
          buff << "\n" << line
        end until line[0, 3] == code and line[3] != ?-
      end
      return buff << "\n"
    end
    private :getmultiline

    # Recieves a response from the destination host.
    #
    # Returns the response code or raises FTPTempError, FTPPermError, or
    # FTPProtoError
    def getresp # :nodoc:
      @last_response = getmultiline
      @last_response_code = @last_response[0, 3]
      case @last_response_code
      when /\A[123]/
        return @last_response
      when /\A4/
        raise FTPTempError, @last_response
      when /\A5/
        raise FTPPermError, @last_response
      else
        raise FTPProtoError, @last_response
      end
    end
    private :getresp

    # Recieves a response.
    #
    # Raises FTPReplyError if the first position of the response code is not
    # equal 2.
    def voidresp # :nodoc:
      resp = getresp
      if resp[0] != ?2
        raise FTPReplyError, resp
      end
    end
    private :voidresp

    #
    # Sends a command and returns the response.
    #
    def sendcmd(cmd)
      synchronize do
        putline(cmd)
        return getresp
      end
    end

    #
    # Sends a command and expect a response beginning with '2'.
    #
    def voidcmd(cmd)
      synchronize do
        putline(cmd)
        voidresp
      end
    end

    # Constructs and send the appropriate PORT (or EPRT) command
    def sendport(host, port) # :nodoc:
      af = (@sock.peeraddr)[0]
      if af == "AF_INET"
        cmd = "PORT " + (host.split(".") + port.divmod(256)).join(",")
      elsif af == "AF_INET6"
        cmd = sprintf("EPRT |2|%s|%d|", host, port)