"""Socket.IO packet."""

# the format of the Socket.IO packet is as follows:

#

# packet type: 1 byte, values 0-6

# num_attachments: ASCII encoded, only if num_attachments != 0

# '-': only if num_attachments != 0

# namespace, followed by a ',': only if namespace != '/'

# id: ASCII encoded, only if id is not None

# data: JSON dump of data payload

uses_binary_events = True

json = _json

def __init__(self, packet_type=EVENT, data=None, namespace=None, id=None,

binary=None, encoded_packet=None):

self.packet_type = packet_type

self.data = data

self.namespace = namespace

self.id = id

if self.uses_binary_events and \

(binary or (binary is None and self._data_is_binary(

self.data))):

if self.packet_type == EVENT:

self.packet_type = BINARY_EVENT

elif self.packet_type == ACK:

self.packet_type = BINARY_ACK

else:

raise ValueError('Packet does not support binary payload.')

self.attachment_count = 0

self.attachments = []

if encoded_packet:

self.attachment_count = self.decode(encoded_packet) or 0

def encode(self):

"""Encode the packet for transmission.

encoded_packet = str(self.packet_type)

if self.packet_type == BINARY_EVENT or self.packet_type == BINARY_ACK:

data, attachments = self._deconstruct_binary(self.data)

encoded_packet += str(len(attachments)) + '-'

else:

data = self.data

attachments = None

if self.namespace is not None and self.namespace != '/':

encoded_packet += self.namespace + ','

if self.id is not None:

encoded_packet += str(self.id)

if data is not None:

encoded_packet += self.json.dumps(data, separators=(',', ':'))

if attachments is not None:

encoded_packet = [encoded_packet] + attachments

return encoded_packet

def decode(self, encoded_packet):

"""Decode a transmitted package.

ep = encoded_packet

try:

self.packet_type = int(ep[0:1])

except TypeError:

self.packet_type = ep

ep = ''

self.namespace = None

self.data = None

ep = ep[1:]

dash = ep.find('-')

attachment_count = 0

if dash > 0 and ep[0:dash].isdigit():

if dash > 10:

raise ValueError('too many attachments')

attachment_count = int(ep[0:dash])

ep = ep[dash + 1:]

if ep and ep[0:1] == '/':

sep = ep.find(',')

if sep == -1:

self.namespace = ep

ep = ''

else:

self.namespace = ep[0:sep]

ep = ep[sep + 1:]

q = self.namespace.find('?')

if q != -1:

self.namespace = self.namespace[0:q]

if ep and ep[0].isdigit():

i = 1

end = len(ep)

while i < end:

if not ep[i].isdigit() or i >= 100:

break

i += 1

self.id = int(ep[:i])

ep = ep[i:]

if len(ep) > 0 and ep[0].isdigit():

raise ValueError('id field is too long')

if ep:

self.data = self.json.loads(ep)

return attachment_count

def add_attachment(self, attachment):

if self.attachment_count <= len(self.attachments):

raise ValueError('Unexpected binary attachment')

self.attachments.append(attachment)

if self.attachment_count == len(self.attachments):

self.reconstruct_binary(self.attachments)

return True

return False

def reconstruct_binary(self, attachments):

"""Reconstruct a decoded packet using the given list of binary

self.data = self._reconstruct_binary_internal(self.data,

self.attachments)

def _reconstruct_binary_internal(self, data, attachments):

if isinstance(data, list):

return [self._reconstruct_binary_internal(item, attachments)

for item in data]

elif isinstance(data, dict):

if data.get('_placeholder') and 'num' in data:

return attachments[data['num']]

else:

return {key: self._reconstruct_binary_internal(value,

attachments)

for key, value in data.items()}

else:

return data

def _deconstruct_binary(self, data):

"""Extract binary components in the packet."""

attachments = []

data = self._deconstruct_binary_internal(data, attachments)

return data, attachments

def _deconstruct_binary_internal(self, data, attachments):

if isinstance(data, bytes):

attachments.append(data)

return {'_placeholder': True, 'num': len(attachments) - 1}

elif isinstance(data, list):

return [self._deconstruct_binary_internal(item, attachments)

for item in data]

elif isinstance(data, dict):

return {key: self._deconstruct_binary_internal(value, attachments)

for key, value in data.items()}

else:

return data

def _data_is_binary(self, data):

"""Check if the data contains binary components."""

if isinstance(data, bytes):

return True

elif isinstance(data, list):

return functools.reduce(

lambda a, b: a or b, [self._data_is_binary(item)

for item in data], False)

elif isinstance(data, dict):

return functools.reduce(

lambda a, b: a or b, [self._data_is_binary(item)

for item in data.values()],

False)

else:

return False

def _to_dict(self):

d = {

'type': self.packet_type,

'data': self.data,

'nsp': self.namespace,

}

if self.id is not None:

d['id'] = self.id