=begin

= net/protocol.rb version 1.2.0

  Copyright (C) 1999-2001 Yukihiro Matsumoto

  written & maintained by Minero Aoki <aamine@dp.u-netsurf.ne.jp>

  This program is free software. You can re-distribute and/or
  modify this program under the same terms as Ruby itself,
  GNU General Public License or Ruby License.

  Japanese version of this document is in "net" full package.
  You can get it from RAA (Ruby Application Archive). RAA is:
  http://www.ruby-lang.org/en/raa.html


== Net::Protocol

the abstract class for some internet protocols

=== Super Class

Object

=== Class Methods

: new( address = 'localhost', port = nil )
  This method Creates a new protocol object.

: start( address = 'localhost', port = nil, *protoargs )
: start( address = 'localhost', port = nil, *protoargs ) {|proto| .... }
  This method creates a new Protocol object and opens a session.
  equals to Net::Protocol.new( address, port ).start( *protoargs )

=== Methods

: address
  the address of connecting server (FQDN).

: port
  connecting port number

: start( *args )
: start( *args ) {|proto| .... }
  This method starts protocol. If protocol was already started,
  do nothing and returns false.

  '*args' are specified in subclasses.

  When is called with block, gives Protocol object to block and
  close session when block finished.

: finish
  This method ends protocol. If you call this method before protocol starts,
  it only return false without doing anything.

: active?
  true if session have been started

=end

require 'socket'
require 'timeout'


module Net

  module NetPrivate
  end

  def self.net_private( &block )
    ::Net::NetPrivate.module_eval( &block )
  end


  class Protocol

    Version = '1.2.0'


    class << self

      def start( address = 'localhost', port = nil, *args )
        instance = new( address, port )

        if block_given? then
          instance.start( *args ) { yield instance }
        else
          instance.start( *args )
          instance
        end
      end

      private

      def protocol_param( name, val )
        module_eval %-
          def self.#{name.id2name}
            #{val}
          end
        -
      end
        
    end


    #
    # sub-class requirements
    #
    # protocol_param command_type
    # protocol_param port
    #
    # private method do_start  (optional)
    # private method do_finish (optional)
    #

    protocol_param :port,         'nil'
    protocol_param :command_type, 'nil'
    protocol_param :socket_type,  '::Net::NetPrivate::Socket'


    def initialize( addr = nil, port = nil )
      @address = addr || 'localhost'
      @port    = port || type.port

      @command = nil
      @socket  = nil

      @active = false

      @open_timeout = nil
      @read_timeout = nil

      @dout = nil
    end

    attr_reader :address
    attr_reader :port

    attr_reader :command
    attr_reader :socket

    attr_accessor :open_timeout
    attr_accessor :read_timeout

    def active?
      @active
    end

    def set_debug_output( arg )   # un-documented
      @dout = arg
    end

    alias set_pipe set_debug_output

    def inspect
      "#<#{type} #{address}:#{port} open=#{active?}>"
    end

    #
    # open session
    #

    def start( *args )
      return false if active?

      if block_given? then
        begin
          _start args
          yield self
        ensure
          finish
        end
      else
        _start args
      end
    end

    private

    def _start( args )
      connect
      do_start( *args )
      @active = true
    end

    def connect
      conn_socket @address, @port
      conn_command @socket
      on_connect
    end

    def re_connect
      @socket.reopen @open_timeout
      on_connect
    end

    def conn_socket( addr, port )
      @socket = type.socket_type.open(
              addr, port, @open_timeout, @read_timeout, @dout )
    end

    def conn_command( sock )
      @command = type.command_type.new( sock )
    end

    def on_connect
    end

    def do_start
    end

    #
    # close session
    #

    public

    def finish
      return false unless active?

      do_finish if @command and not @command.critical?
      disconnect
      @active = false
      true
    end

    private

    def do_finish
      @command.quit
    end

    def disconnect
      @command = nil
      if @socket and not @socket.closed? then
        @socket.close
      end
      @socket = nil
      on_disconnect
    end

    def on_disconnect
    end
    
  end

  Session = Protocol


  net_private {

  class Response

    def initialize( ctype, cno, msg )
      @code_type = ctype
      @code      = cno
      @message   = msg
      super()
    end

    attr_reader :code_type, :code, :message
    alias msg message

    def inspect
      "#<#{type} #{code}>"
    end

    def error!( data = nil )
      raise code_type.error_type.new( code + ' ' + Net.quote(msg), data )
    end

  end

  }


  class ProtocolError          < StandardError; end
  class ProtoSyntaxError       < ProtocolError; end
  class ProtoFatalError        < ProtocolError; end
  class ProtoUnknownError      < ProtocolError; end
  class ProtoServerError       < ProtocolError; end
  class ProtoAuthError         < ProtocolError; end
  class ProtoCommandError      < ProtocolError; end
  class ProtoRetriableError    < ProtocolError; end
  ProtocRetryError = ProtoRetriableError

  class ProtocolError
  
    def initialize( msg, data = nil )
      super msg
      @data = data
    end

    attr :data

    def inspect
      "#<#{type}>"
    end
  
  end


  class Code

    def initialize( paren, err )
      @parents = paren
      @err = err

      @parents.push self
    end

    attr_reader :parents

    def inspect
      "#<#{type}>"
    end

    def error_type
      @err
    end

    def ===( response )
      response.code_type.parents.reverse_each {|i| return true if i == self }
      false
    end

    def mkchild( err = nil )
      type.new( @parents + [self], err || @err )
    end
  
  end
  
  ReplyCode       = Code.new( [], ProtoUnknownError )
  InformationCode = ReplyCode.mkchild( ProtoUnknownError )
  SuccessCode     = ReplyCode.mkchild( ProtoUnknownError )
  ContinueCode    = ReplyCode.mkchild( ProtoUnknownError )
  ErrorCode       = ReplyCode.mkchild( ProtocolError )
  SyntaxErrorCode = ErrorCode.mkchild( ProtoSyntaxError )
  FatalErrorCode  = ErrorCode.mkchild( ProtoFatalError )
  ServerErrorCode = ErrorCode.mkchild( ProtoServerError )
  AuthErrorCode   = ErrorCode.mkchild( ProtoAuthError )
  RetriableCode   = ReplyCode.mkchild( ProtoRetriableError )
  UnknownCode     = ReplyCode.mkchild( ProtoUnknownError )



  net_private {

  class WriteAdapter

    def initialize( sock, mid )
      @sock = sock
      @mid = mid
    end

    def inspect
      "#<#{type}>"
    end

    def write( str )
      @sock.__send__ @mid, str
    end

    alias << write
  
  end

  class ReadAdapter

    def initialize( block )
      @block = block
    end

    def inspect
      "#<#{type}>"
    end

    def <<( str )
      callblock( str, &@block ) if @block
    end

    private

    def callblock( str )
      begin
        user_break = true
        yield str
        user_break = false
      rescue Exception
        user_break = false
        raise
      ensure
        if user_break then
          @block = nil
          return   # stop break
        end
      end
    end
  
  end



  class Command

    def initialize( sock )
      @socket = sock
      @last_reply = nil
      @critical = false
    end

    attr_accessor :socket
    attr_reader :last_reply

    def inspect
      "#<#{type}>"
    end

    # abstract quit


    private

    # abstract get_reply()

    def check_reply( *oks )
      @last_reply = get_reply
      reply_must( @last_reply, *oks )
    end

    def reply_must( rep, *oks )
      oks.each do |i|
        if i === rep then
          return rep
        end
      end
      rep.error!
    end

    def getok( line, expect = SuccessCode )
      @socket.writeline line
      check_reply expect
    end


    #
    # error handle
    #

    public

    def critical?
      @critical
    end

    def error_ok
      @critical = false
    end


    private

    def critical
      @critical = true
      ret = yield
      @critical = false
      ret
    end

    def begin_critical
      ret = @critical
      @critical = true
      not ret
    end

    def end_critical
      @critical = false
    end

  end


  class Socket

    def initialize( addr, port, otime = nil, rtime = nil, dout = nil )
      @addr = addr
      @port = port

      @read_timeout = rtime

      @debugout = dout

      @socket = nil
      @sending = ''
      @buffer  = ''

      connect otime
      D 'opened'
    end

    def connect( otime )
      D "opening connection to #{@addr}..."
      timeout( otime ) {
        @socket = TCPsocket.new( @addr, @port )
      }
    end
    private :connect

    attr :pipe, true

    class << self
      alias open new
    end

    def inspect
      "#<#{type} #{closed? ? 'closed' : 'opened'}>"
    end

    def reopen( otime = nil )
      D 'reopening...'
      close
      connect otime
      D 'reopened'
    end

    attr :socket, true

    def close
      if @socket then
        @socket.close
        D 'closed'
      else
        D 'close call for already closed socket'
      end
      @socket = nil
      @buffer = ''
    end

    def closed?
      not @socket
    end

    def address
      @addr.dup
    end

    alias addr address

    attr_reader :port

    def ip_address
      @socket or return ''
      @socket.addr[3]
    end

    alias ipaddr ip_address

    attr_reader :sending


    #
    # read
    #

    public

    CRLF = "\r\n"

    def read( len, dest = '', ignerr = false )
      D_off "reading #{len} bytes..."

      rsize = 0
      begin
        while rsize + @buffer.size < len do
          rsize += rbuf_moveto( dest, @buffer.size )
          rbuf_fill
        end
        rbuf_moveto dest, len - rsize
      rescue EOFError
        raise unless igneof
      end

      D_on "read #{len} bytes"
      dest
    end

    def read_all( dest = '' )
      D_off 'reading all...'

      rsize = 0
      begin
        while true do
          rsize += rbuf_moveto( dest, @buffer.size )
          rbuf_fill
        end
      rescue EOFError
        ;
      end

      D_on "read #{rsize} bytes"
      dest
    end

    def readuntil( target, igneof = false )
      dest = ''
      begin
        while true do
          idx = @buffer.index( target )
          break if idx
          rbuf_fill
        end
        rbuf_moveto dest, idx + target.size
      rescue EOFError
        raise unless igneof
        rbuf_moveto dest, @buffer.size
      end
      dest
    end
        
    def readline
      ret = readuntil( "\n" )
      ret.chop!
      ret
    end

    def read_pendstr( dest )
      D_off 'reading text...'

      rsize = 0
      while (str = readuntil("\r\n")) != ".\r\n" do
        rsize += str.size
        str.gsub!( /\A\./, '' )
        dest << str
      end

      D_on "read #{rsize} bytes"
      dest
    end

    # private use only (can not handle 'break')
    def read_pendlist
      D_off 'reading list...'

      str = nil
      i = 0
      while (str = readuntil("\r\n")) != ".\r\n" do
        i += 1
        str.chop!
        yield str
      end

      D_on "read #{i} items"
    end


    private


    READ_SIZE = 1024 * 4

    def rbuf_fill
      unless IO.select [@socket], nil, nil, @read_timeout then
        on_read_timeout
      end
      @buffer << @socket.sysread( READ_SIZE )
    end

    def on_read_timeout
      raise TimeoutError, "socket read timeout (#{@read_timeout} sec)"
    end

    def rbuf_moveto( dest, len )
      bsi = @buffer.size
      s = @buffer[ 0, len ]
      dest << s
      @buffer = @buffer[ len, bsi - len ]

      @debugout << %<read  "#{Net.quote s}"\n> if @debugout
      len
    end


    #
    # write interfece
    #

    public

    def write( str )
      writing {
        do_write str
      }
    end

    def writeline( str )
      writing {
        do_write str + "\r\n"
      }
    end

    def write_bin( src, block )
      writing {
        if block then
          block.call ::Net::NetPrivate::WriteAdapter.new( self, :do_write )
        else
          src.each do |bin|
            do_write bin
          end
        end
      }
    end

    def write_pendstr( src, block )
      D_off "writing text from #{src.type}"

      wsize = use_each_crlf_line {
        if block then
          block.call ::Net::NetPrivate::WriteAdapter.new( self, :wpend_in )
        else
          wpend_in src
        end
      }

      D_on "wrote #{wsize} bytes text"
      wsize
    end


    private


    def wpend_in( src )
      line = nil
      pre = @writtensize
      each_crlf_line( src ) do |line|
        do_write '.' if line[0] == ?.
        do_write line
      end

      @writtensize - pre
    end

    def use_each_crlf_line
      writing {
        @wbuf = ''

        yield

        if not @wbuf.empty? then       # un-terminated last line
          if @wbuf[-1] == ?\r then
            @wbuf.chop!
          end
          @wbuf.concat "\r\n"
          do_write @wbuf
        elsif @writtensize == 0 then   # empty src
          do_write "\r\n"
        end
        do_write ".\r\n"

        @wbuf = nil
      }
    end

    def each_crlf_line( src )
      str = m = beg = nil

      adding( src ) do
        beg = 0
        buf = @wbuf
        while buf.index( /\n|\r\n|\r/, beg ) do
          m = Regexp.last_match
          if m.begin(0) == buf.size - 1 and buf[-1] == ?\r then
            # "...\r" : can follow "\n..."
            break
          end
          str = buf[ beg ... m.begin(0) ]
          str.concat "\r\n"
          yield str
          beg = m.end(0)
        end
        @wbuf = buf[ beg ... buf.size ]
      end
    end

    def adding( src )
      i = nil

      case src
      when String
        0.step( src.size - 1, 2048 ) do |i|
          @wbuf << src[i,2048]
          yield
        end

      when File
        while true do
          i = src.read( 2048 )
          break unless i
          i[0,0] = @wbuf
          @wbuf = i
          yield
        end

      else
        src.each do |i|
          @wbuf << i
          if @wbuf.size > 2048 then
            yield
          end
        end
        yield unless @wbuf.empty?
      end
    end


    def writing
      @writtensize = 0
      @sending = ''

      yield

      if @debugout then
        @debugout << 'write "'
        @debugout << @sending
        @debugout << "\"\n"
      end
      @socket.flush
      @writtensize
    end

    def do_write( arg )
      if @debugout or @sending.size < 128 then
        @sending << Net.quote( arg )
      else
        @sending << '...' unless @sending[-1] == ?.
      end

      s = @socket.write( arg )
      @writtensize += s
      s
    end


    def D_off( msg )
      D msg
      @savedo, @debugout = @debugout, nil
    end

    def D_on( msg )
      @debugout = @savedo
      D msg
    end

    def D( msg )
      @debugout or return
      @debugout << msg
      @debugout << "\n"
    end

  end

  }


  def Net.quote( str )
    str = str.gsub( "\n", '\\n' )
    str.gsub!( "\r", '\\r' )
    str.gsub!( "\t", '\\t' )
    str
  end

end   # module Net