import functools

from newrelic.agent import (wrap_function_wrapper, current_transaction,
        ExternalTrace)
import newrelic.api.external_trace

def _nr_wrapper_httplib2_connect_wrapper(scheme):

    def _nr_wrapper_httplib2_connect_wrapper_inner(wrapped, instance, args,
            kwargs):
        transaction = current_transaction()

        if transaction is None:
            return wrapped(*args, **kwargs)

        def _connect_unbound(instance, *args, **kwargs):
            return instance

        if instance is None:
            instance = _connect_unbound(*args, **kwargs)

        connection = instance

        url = '%s://%s:%s' % (scheme, connection.host, connection.port)

        with ExternalTrace(transaction, library='httplib2', url=url) as tracer:
            # Add the tracer to the connection object. The tracer will be
            # used in getresponse() to add back into the external trace,
            # after the trace has already completed, details from the
            # response headers.

            connection._nr_external_tracer = tracer

            return wrapped(*args, **kwargs)

    return _nr_wrapper_httplib2_connect_wrapper_inner

def instrument(module):

    wrap_function_wrapper(module, 'HTTPConnectionWithTimeout.connect',
            _nr_wrapper_httplib2_connect_wrapper('http'))

    wrap_function_wrapper(module, 'HTTPSConnectionWithTimeout.connect',
            _nr_wrapper_httplib2_connect_wrapper('https'))

    def url_request(connection, uri, *args, **kwargs):
        return uri

    newrelic.api.external_trace.wrap_external_trace(
           module, 'Http.request', 'httplib2', url_request)