from tornado import ioloop, web

from cStringIO import StringIO
import functools


class ChunkedHandler(web.RequestHandler):
    def post(self):
        # we assume that the wrapping server has not sent/flushed the
        # 100 (Continue) response
        if self.request.headers.get('Expect', None) == '100-continue' and \
            not 'Content-Length' in self.request.headers and \
            self.request.headers.get('Transfer-Encoding', None) == 'chunked':

            self._auto_finish = False

            self.chunks = StringIO()
            self._stream = self.request.connection.stream

            # cache callback proxies
            self._length_callback = lambda: \
                self._stream.read_until('\r\n', self._on_chunk_length)
            self._data_callback = lambda len: \
                lambda: self._stream.read_bytes(len + 2, self._on_chunk_data)

            self._stream.io_loop.add_callback(self._length_callback)

            self.request.write("HTTP/1.1 100 (Continue)\r\n\r\n")
        else:
            raise web.HTTPError(500, "non-chunked request")

    def _on_chunks(self, all_chunks):
        self.finish()
        print "got all chunks, total size=%d" % all_chunks.tell()

    def _on_chunk_length(self, data):
        assert data[-2:] == '\r\n', "chunk size ends with CRLF"
        chunk_length = int(data[:-2], 16)

        if chunk_length:
            self._stream.io_loop.add_callback(self._data_callback(chunk_length))
        else:
            self._on_chunks(self.chunks)

    def _on_chunk_data(self, data):
        assert data[-2:] == '\r\n', "chunk data ends with CRLF"
        self.chunks.write(data[:-2])

        self._stream.io_loop.add_callback(self._length_callback)