class WebSocket::Handshake::Handler::Server76

def challenge_response
  # Refer to 5.2 4-9 of the draft 76
  first = numbers_over_spaces(@handshake.headers['sec-websocket-key1'].to_s)
  second = numbers_over_spaces(@handshake.headers['sec-websocket-key2'].to_s)
  third = @handshake.leftovers
  sum = [first].pack('N*') +
        [second].pack('N*') +
        third
  Digest::MD5.digest(sum)
end

def finishing_line
  @finishing_line ||= challenge_response
end

def header_line
  'HTTP/1.1 101 WebSocket Protocol Handshake'
end

def headers
  {
    origin: 'Sec-WebSocket-Origin',
    location: 'Sec-WebSocket-Location',
    protocol: 'Sec-WebSocket-Protocol'
  }.freeze
end

def numbers_over_spaces(string)
  numbers = string.scan(/[0-9]/).join.to_i
  spaces = string.scan(/ /).size
  # As per 5.2.5, abort the connection if spaces are zero.
  raise WebSocket::Error::Handshake::InvalidAuthentication if spaces.zero?
  # As per 5.2.6, abort if numbers is not an integral multiple of spaces
  raise WebSocket::Error::Handshake::InvalidAuthentication if numbers % spaces != 0
  quotient = numbers / spaces
  raise WebSocket::Error::Handshake::InvalidAuthentication if quotient > 2**32 - 1
  quotient
end

def reserved_leftover_lines
  1
end

def valid?
  super && !finishing_line.nil?
end