import httplib, socket

class ProgressReportingHTTPConnection(httplib.HTTPConnection):
  """An HTTPConnection which sends data in small blocks and
  calls an optional callback so you can see that it's making progress.
  
  Pass the callback function as progress_callback to constructor. The callback
  function takes two parameters, i and l; i is the amount of data transferred,
  l is the total amount of data being sent.
  
  Also allows you to abort connections.
  
  """
  def __init__(self, host, port=None, strict=None, progress_callback=None):
    httplib.HTTPConnection.__init__(self, host, port, strict)
    self.progress_callback = progress_callback
    self.ABORT_CONNECTION = False
    
  def abort_connection(self):
    self.ABORT_CONNECTION = True
    
  def send(self, str):
    """Send `str' to the server."""
    if self.sock is None:
      if self.auto_open:
        try:
          self.connect()
        except:
          self.connect() # try one more time!
      else:
        raise NotConnected()

    # send the data to the server. if we get a broken pipe, then close
    # the socket. we want to reconnect when somebody tries to send again.
    #
    # NOTE: we DO propagate the error, though, because we cannot simply
    #       ignore the error... the caller will know if they can retry.
    if self.debuglevel > 0:
      print "send:", repr(str)
    try:
      if self.progress_callback:
        BLOCK_SIZE = 2048 # 2K blocks
        l = len(str)
        for i in range(0,l,BLOCK_SIZE):
          self.sock.sendall(str[i:i+BLOCK_SIZE])
          self.progress_callback(i,l)
          if self.ABORT_CONNECTION:
            self.close()
            return

        # report completion
        self.progress_callback(l,l)
      else:
        self.sock.sendall(str)        
    except socket.error, v:
      if v[0] == 32:      # Broken pipe
        self.close()
      raise