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import urlparse
from mod_pywebsocket.extensions import DeflateFrameExtensionProcessor
from mod_pywebsocket.extensions import ExtensionProcessorInterface
from mod_pywebsocket.common import ExtensionParameter


_GOODBYE_MESSAGE = u'Goodbye'
_ENABLE_MESSAGE = u'EnableCompression'
_DISABLE_MESSAGE = u'DisableCompression'


def _get_deflate_frame_extension_processor(request):
    for extension_processor in request.ws_extension_processors:
        if isinstance(extension_processor, DeflateFrameExtensionProcessor):
            return extension_processor
    return None


def web_socket_do_extra_handshake(request):
    processor = _get_deflate_frame_extension_processor(request)
    if not processor:
        return
    # Avoid extension conflict.
    request.ws_extension_processors = [processor]

    r = request.ws_resource.split('?', 1)
    if len(r) == 1:
        return
    parameters = urlparse.parse_qs(r[1], keep_blank_values=True)
    if 'max_window_bits' in parameters:
        window_bits = int(parameters['max_window_bits'][0])
        processor.set_response_window_bits(window_bits)
    if 'no_context_takeover' in parameters:
        processor.set_response_no_context_takeover(True)
    if 'set_bfinal' in parameters:
        processor.set_bfinal(True)


def web_socket_transfer_data(request):
    processor = _get_deflate_frame_extension_processor(request)
    while True:
        line = request.ws_stream.receive_message()
        if line is None:
            return
        if isinstance(line, unicode):
            if processor:
                if line == _ENABLE_MESSAGE:
                    processor.enable_outgoing_compression()
                elif line == _DISABLE_MESSAGE:
                    processor.disable_outgoing_compression()
            request.ws_stream.send_message(line, binary=False)
            if line == _GOODBYE_MESSAGE:
                return
        else:
            request.ws_stream.send_message(line, binary=True)


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