class NNTPError < Exception
  attr :message

  def initialize(message)
    @message = message
  end
end

class NNTPSession
  attr_reader :group, :article, :user, :auth_user_name

  def initialize(socket, logger)
    @socket = socket
    @logger = logger
  end

  def write(s)
    @socket.write s
  end

  def putline(line)
    @socket.write(line.chomp + "\r\n")
    @logger.debug { "Thread #{Thread.current.id}: > #{line.chomp}" }
  end

  # Read a single line from the client and return it.
  def getline
    line = @socket.gets("\n").chomp
    @logger.debug { "Thread #{Thread.current.id}: < #{line}" }
    return line
  end

  # Read a multi-line message from a client.
  def getarticle
    # TODO
  end

  def close
    @socket.close
  end

  def serve
    putline "200 server ready"
    while request = getline.strip
      cmd, *args = request.split(/\s+/)
      
      begin
        case request

        when /^LIST$/i
          write Forum.nntp_grouplist.join("\r\n") + "\r\n"
          putline '.'
      
        when /^LIST OVERVIEW\.FMT$/i
          write "Subject:\r\nFrom:\r\nDate:\r\nMessage-Id:\r\nReferences:\r\nBytes:\r\nLines:\r\n"
          putline '.'
      
        when /^GROUP (.+)$/i
          putline select_group($1)
    
        when /^AUTHINFO USER (.+)$/i
          @auth_user_name = $1
          @user = nil
          putline '381 More authentication information required'
    
        when /^AUTHINFO PASS (.+)$/i
          if @auth_user_name
            # try login
            @user = User.find_by_login(@auth_user_name, $1)
            if @user
              putline '281 Authentication accepted'
            else
              putline '502 No permission'
            end
          else
            # password without username
            putline '482 Authentication rejected'
          end
          
        when /^NEWNEWS/i
          putline '502 permission denied (command disabled)'

        when /^SLAVE$/i
          putline '202 ignored'

        when /^MODE READER$/i
          putline '200 ignored'
      
        when /^IHAVE/i
          putline '435 article not wanted - do not send it'
    
        when /^QUIT$/i
          putline '205 closing connection'
          close
          return

        else
          raise NNTPError, '500 unknown command'
        end
      rescue NNTPError => err
        putline err.message
      end
      
    end
  end

  def select_group(name)
    @group = Forum.find_by_groupname(name)
    '211 foo'
  rescue
    '411 group not found'
  end

end