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# mqtt/client.py

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from __future__ import absolute_import

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import os

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from POULibrary import POULibrary

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import util.paths as paths

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mqtt_python_lib_code = """

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def MQTT_publish(clientname, topic, payload, QoS = 1, Retained = False):

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    c_function_name = "__mqtt_python_publish_" + clientname

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    c_function = getattr(PLCBinary, c_function_name)

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    c_function.restype = ctypes.c_int # error or 0

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    c_function.argtypes = [

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        ctypes.c_char_p,  # topic

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        ctypes.c_char_p,  # data

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        ctypes.c_uint32,  # datalen

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        ctypes.c_uint8,   # QoS

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        ctypes.c_uint8,   # Retained

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    ]

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    res = c_function(topic, payload, len(payload), QoS, Retained)

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    return res

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# C per client CallBack type for __mqtt_python_onmsg_{name}

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mqtt_c_cb_onmsg_type = ctypes.CFUNCTYPE(ctypes.c_int,                   # return

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                                        ctypes.c_char_p,                # topic

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                                        ctypes.POINTER(ctypes.c_char),  # data

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                                        ctypes.c_uint32)                # data length

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# C per client CallBack type for __mqtt_python_resub_{name}

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mqtt_c_cb_resub_type = ctypes.CFUNCTYPE(ctypes.c_int)                  # return

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# CallBacks management

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# - each call to MQTT_subscribe registers a callback

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MQTT_subscribers_cbs = {}

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# - one callback registered to C side per client

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MQTT_client_cbs = {}

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def mqtt_per_client_cb_factory(clientname):

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    def per_client_onmsg_cb(topic, dataptr, datalen):

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        payload = ctypes.string_at(dataptr, datalen)

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        subscriber,_Qos = MQTT_subscribers_cbs[clientname].get(topic, None)

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        if subscriber:

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            subscriber(topic, payload)

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            return 0

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        return 1

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    def per_client_resub_cb():

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        for topic,(_cb,QoS) in MQTT_subscribers_cbs[clientname].items():

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            _MQTT_subscribe(clientname, topic, QoS)

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        return 1

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    return per_client_onmsg_cb,per_client_resub_cb

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def _MQTT_subscribe(clientname, topic, QoS):

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    c_function_name = "__mqtt_python_subscribe_" + clientname

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    c_function = getattr(PLCBinary, c_function_name)

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    c_function.restype = ctypes.c_int # error or 0

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    c_function.argtypes = [

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        ctypes.c_char_p,  # topic

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        ctypes.c_uint8]   # QoS

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    return c_function(topic, QoS)

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def MQTT_subscribe(clientname, topic, cb, QoS = 1):

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    global MQTT_client_cbs, MQTT_subscribers_cbs

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    MQTT_subscribers_cbs.setdefault(clientname, {})[topic] = (cb, QoS)

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    res = _MQTT_subscribe(clientname, topic, QoS)

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    c_cbs = MQTT_client_cbs.get(clientname, None)

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    if c_cbs is None:

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        cb_onmsg, cb_resub = mqtt_per_client_cb_factory(clientname)

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        c_cbs = (mqtt_c_cb_onmsg_type(cb_onmsg),

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                 mqtt_c_cb_resub_type(cb_resub))

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        MQTT_client_cbs[clientname] = c_cbs

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        register_c_function = getattr(PLCBinary, "__mqtt_python_callback_setter_"+clientname )

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        register_c_function.argtypes = [mqtt_c_cb_onmsg_type, mqtt_c_cb_resub_type]

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        register_c_function(*c_cbs)

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    return res

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"""

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class MQTTLibrary(POULibrary):

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    def GetLibraryPath(self):

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        return paths.AbsNeighbourFile(__file__, "pous.xml")

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    def Generate_C(self, buildpath, varlist, IECCFLAGS):

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        runtimefile_path = os.path.join(buildpath, "runtime_00_mqtt.py")

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        runtimefile = open(runtimefile_path, 'w')

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        runtimefile.write(mqtt_python_lib_code)

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        runtimefile.close()

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        return ((["mqtt"], [], False), "",

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                ("runtime_00_mqtt.py", open(runtimefile_path, "rb")))