"""
# an API for Meshtastic devices

Primary class: StreamInterface
Install with pip: "[pip3 install meshtastic](https://pypi.org/project/meshtastic/)"
Source code on [github](https://github.com/meshtastic/Meshtastic-python)

properties of StreamInterface:

- radioConfig - Current radio configuration and device settings, if you write to this the new settings will be applied to
the device.
- nodes - The database of received nodes.  Includes always up-to-date location and username information for each
node in the mesh.  This is a read-only datastructure.
- myNodeInfo - Contains read-only information about the local radio device (software version, hardware version, etc)

# Published PubSub topics

We use a [publish-subscribe](https://pypubsub.readthedocs.io/en/v4.0.3/) model to communicate asynchronous events.  Available
topics:

- meshtastic.connection.established - published once we've successfully connected to the radio and downloaded the node DB
- meshtastic.connection.lost - published once we've lost our link to the radio
- meshtastic.receive.position(packet) - delivers a received packet as a dictionary, if you only care about a particular
type of packet, you should subscribe to the full topic name.  If you want to see all packets, simply subscribe to "meshtastic.receive".
- meshtastic.receive.user(packet)
- meshtastic.receive.data(packet)
- meshtastic.node.updated(node = NodeInfo) - published when a node in the DB changes (appears, location changed, username changed, etc...)

# Example Usage
```
import meshtastic
from pubsub import pub

def onReceive(packet, interface): # called when a packet arrives
    print(f"Received: {packet}")

def onConnection(interface, topic=pub.AUTO_TOPIC): # called when we (re)connect to the radio
    # defaults to broadcast, specify a destination ID if you wish
    interface.sendText("hello mesh")

pub.subscribe(onReceive, "meshtastic.receive")
pub.subscribe(onConnection, "meshtastic.connection.established")
# By default will try to find a meshtastic device, otherwise provide a device path like /dev/ttyUSB0
interface = meshtastic.StreamInterface()

```

"""

import pygatt
import google.protobuf.json_format
import serial
import threading
import logging
import time
import sys
import traceback
import time
import base64
import platform
from . import mesh_pb2
from . import util
from pubsub import pub
from dotmap import DotMap

START1 = 0x94
START2 = 0xc3
HEADER_LEN = 4
MAX_TO_FROM_RADIO_SIZE = 512

BROADCAST_ADDR = "^all"  # A special ID that means broadcast

# if using 8 bit nodenums this will be shortend on the target
BROADCAST_NUM = 0xffffffff

MY_CONFIG_ID = 42

"""The numeric buildnumber (shared with android apps) specifying the level of device code we are guaranteed to understand"""
OUR_APP_VERSION = 172


class MeshInterface:
    """Interface class for meshtastic devices

    Properties:

    isConnected
    nodes
    debugOut
    """

    def __init__(self, debugOut=None, noProto=False):
        """Constructor"""
        self.debugOut = debugOut
        self.nodes = None  # FIXME
        self.isConnected = False
        if not noProto:
            self._startConfig()

    def sendText(self, text, destinationId=BROADCAST_ADDR, wantAck=False, wantResponse=False):
        """Send a utf8 string to some other node, if the node has a display it will also be shown on the device.

        Arguments:
            text {string} -- The text to send

        Keyword Arguments:
            destinationId {nodeId or nodeNum} -- where to send this message (default: {BROADCAST_ADDR})
            wantAck -- True if you want the message sent in a reliable manner (with retries and ack/nak provided for delivery)

        Returns the sent packet. The id field will be populated in this packet and can be used to track future message acks/naks.
        """
        return self.sendData(text.encode("utf-8"), destinationId,
                             dataType=mesh_pb2.Data.CLEAR_TEXT, wantAck=wantAck, wantResponse=wantResponse)

    def sendData(self, byteData, destinationId=BROADCAST_ADDR, dataType=mesh_pb2.Data.OPAQUE, wantAck=False, wantResponse=False):
        """Send a data packet to some other node

        Keyword Arguments:
            destinationId {nodeId or nodeNum} -- where to send this message (default: {BROADCAST_ADDR})
            wantAck -- True if you want the message sent in a reliable manner (with retries and ack/nak provided for delivery)

        Returns the sent packet. The id field will be populated in this packet and can be used to track future message acks/naks.
        """
        meshPacket = mesh_pb2.MeshPacket()
        meshPacket.decoded.data.payload = byteData
        meshPacket.decoded.data.typ = dataType
        meshPacket.decoded.want_response = wantResponse
        return self.sendPacket(meshPacket, destinationId, wantAck=wantAck)

    def sendPosition(self, latitude=0.0, longitude=0.0, altitude=0, timeSec=0, destinationId=BROADCAST_ADDR, wantAck=False, wantResponse=False):
        """
        Send a position packet to some other node (normally a broadcast)

        Also, the device software will notice this packet and use it to automatically set its notion of
        the local position.

        If timeSec is not specified (recommended), we will use the local machine time.

        Returns the sent packet. The id field will be populated in this packet and can be used to track future message acks/naks.
        """
        meshPacket = mesh_pb2.MeshPacket()
        if(latitude != 0.0):
            meshPacket.decoded.position.latitude_i = int(latitude / 1e-7)

        if(longitude != 0.0):
            meshPacket.decoded.position.longitude_i = int(longitude / 1e-7)

        if(altitude != 0):
            meshPacket.decoded.position.altitude = int(altitude)

        if timeSec == 0:
            timeSec = time.time()  # returns unix timestamp in seconds
        meshPacket.decoded.position.time = int(timeSec)

        meshPacket.decoded.want_response = wantResponse
        return self.sendPacket(meshPacket, destinationId, wantAck=wantAck)

    def sendPacket(self, meshPacket, destinationId=BROADCAST_ADDR, wantAck=False):
        """Send a MeshPacket to the specified node (or if unspecified, broadcast).
        You probably don't want this - use sendData instead.

        Returns the sent packet. The id field will be populated in this packet and can be used to track future message acks/naks.
        """
        toRadio = mesh_pb2.ToRadio()
        # FIXME add support for non broadcast addresses

        if isinstance(destinationId, int):
            nodeNum = destinationId
        elif destinationId == BROADCAST_ADDR:
            nodeNum = BROADCAST_NUM
        else:
            nodeNum = self.nodes[destinationId]['num']

        meshPacket.to = nodeNum
        meshPacket.want_ack = wantAck

        # if the user hasn't set an ID for this packet (likely and recommended), we should pick a new unique ID
        # so the message can be tracked.
        if meshPacket.id == 0:
            meshPacket.id = self._generatePacketId()

        toRadio.packet.CopyFrom(meshPacket)
        self._sendToRadio(toRadio)
        return meshPacket

    def writeConfig(self):
        """Write the current (edited) radioConfig to the device"""
        if self.radioConfig == None:
            raise Exception("No RadioConfig has been read")

        t = mesh_pb2.ToRadio()
        t.set_radio.CopyFrom(self.radioConfig)
        self._sendToRadio(t)

    @property
    def channelURL(self):
        """The sharable URL that describes the current channel
        """
        bytes = self.radioConfig.channel_settings.SerializeToString()
        s = base64.urlsafe_b64encode(bytes).decode('ascii')
        return f"https://www.meshtastic.org/c/#{s}"

    def _generatePacketId(self):
        """Get a new unique packet ID"""
        if self.currentPacketId is None:
            raise Exception("Not connected yet, can not generate packet")
        else:
            self.currentPacketId = (self.currentPacketId + 1) & 0xffffffff
            return self.currentPacketId

    def _disconnected(self):
        """Called by subclasses to tell clients this interface has disconnected"""
        self.isConnected = False
        pub.sendMessage("meshtastic.connection.lost", interface=self)

    def _connected(self):
        """Called by this class to tell clients we are now fully connected to a node
        """
        self.isConnected = True
        pub.sendMessage("meshtastic.connection.established", interface=self)

    def _startConfig(self):
        """Start device packets flowing"""
        self.myInfo = None
        self.nodes = {}  # nodes keyed by ID
        self._nodesByNum = {}  # nodes keyed by nodenum
        self.radioConfig = None
        self.currentPacketId = None

        startConfig = mesh_pb2.ToRadio()
        startConfig.want_config_id = MY_CONFIG_ID  # we don't use this value
        self._sendToRadio(startConfig)

    def _sendToRadio(self, toRadio):
        """Send a ToRadio protobuf to the device"""
        logging.error(f"Subclass must provide toradio: {toRadio}")

    def _handleFromRadio(self, fromRadioBytes):
        """
        Handle a packet that arrived from the radio(update model and publish events)

        Called by subclasses."""
        fromRadio = mesh_pb2.FromRadio()
        fromRadio.ParseFromString(fromRadioBytes)
        asDict = google.protobuf.json_format.MessageToDict(fromRadio)
        logging.debug(f"Received: {asDict}")
        if fromRadio.HasField("my_info"):
            self.myInfo = fromRadio.my_info
            if self.myInfo.min_app_version > OUR_APP_VERSION:
                raise Exception(
                    "This device needs a newer python client, please \"pip install --upgrade meshtastic\"")
            # start assigning our packet IDs from the opposite side of where our local device is assigning them
            self.currentPacketId = (
                self.myInfo.current_packet_id + 0x80000000) & 0xffffffff
        elif fromRadio.HasField("radio"):
            self.radioConfig = fromRadio.radio
        elif fromRadio.HasField("node_info"):
            node = asDict["nodeInfo"]
            try:
                self._fixupPosition(node["position"])
            except:
                logging.debug("Node without position")
            self._nodesByNum[node["num"]] = node
            if "user" in node:  # Some nodes might not have user/ids assigned yet
                self.nodes[node["user"]["id"]] = node
        elif fromRadio.config_complete_id == MY_CONFIG_ID:
            # we ignore the config_complete_id, it is unneeded for our stream API fromRadio.config_complete_id
            self._connected()
        elif fromRadio.HasField("packet"):
            self._handlePacketFromRadio(fromRadio.packet)
        elif fromRadio.rebooted:
            self._disconnected()
            self._startConfig()  # redownload the node db etc...
        else:
            logging.warn("Unexpected FromRadio payload")

    def _fixupPosition(self, position):
        """Convert integer lat/lon into floats

        Arguments:
            position {Position dictionary} -- object ot fix up
        """
        if "latitudeI" in position:
            position["latitude"] = position["latitudeI"] * 1e-7
        if "longitudeI" in position:
            position["longitude"] = position["longitudeI"] * 1e-7

    def _nodeNumToId(self, num):
        """Map a node node number to a node ID

        Arguments:
            num {int} -- Node number

        Returns:
            string -- Node ID
        """
        if num == BROADCAST_NUM:
            return BROADCAST_ADDR

        try:
            return self._nodesByNum[num]["user"]["id"]
        except:
            logging.warn("Node not found for fromId")
            return None

    def _getOrCreateByNum(self, nodeNum):
        """Given a nodenum find the NodeInfo in the DB (or create if necessary)"""
        if nodeNum == BROADCAST_NUM:
            raise Exception("Can not create/find nodenum by the broadcast num")

        if nodeNum in self._nodesByNum:
            return self._nodesByNum[nodeNum]
        else:
            n = {"num": nodeNum}  # Create a minimial node db entry
            self._nodesByNum[nodeNum] = n
            return n

    def _handlePacketFromRadio(self, meshPacket):
        """Handle a MeshPacket that just arrived from the radio

        Will publish one of the following events:
        - meshtastic.receive.position(packet = MeshPacket dictionary)
        - meshtastic.receive.user(packet = MeshPacket dictionary)
        - meshtastic.receive.data(packet = MeshPacket dictionary)
        """

        asDict = google.protobuf.json_format.MessageToDict(meshPacket)
        # /add fromId and toId fields based on the node ID
        asDict["fromId"] = self._nodeNumToId(asDict["from"])
        asDict["toId"] = self._nodeNumToId(asDict["to"])

        # We could provide our objects as DotMaps - which work with . notation or as dictionaries
        # asObj = DotMap(asDict)
        topic = "meshtastic.receive"  # Generic unknown packet type
        if meshPacket.decoded.HasField("position"):
            topic = "meshtastic.receive.position"
            p = asDict["decoded"]["position"]
            self._fixupPosition(p)
            # update node DB as needed
            self._getOrCreateByNum(asDict["from"])["position"] = p

        if meshPacket.decoded.HasField("user"):
            topic = "meshtastic.receive.user"
            u = asDict["decoded"]["user"]
            # update node DB as needed
            n = self._getOrCreateByNum(asDict["from"])
            n["user"] = u
            # We now have a node ID, make sure it is uptodate in that table
            self.nodes[u["id"]] = u

        if meshPacket.decoded.HasField("data"):
            topic = "meshtastic.receive.data"

            # OPAQUE is the default protobuf typ value, and therefore if not set it will not be populated at all
            # to make API usage easier, set it to prevent confusion
            if not "typ" in asDict["decoded"]["data"]:
                asDict["decoded"]["data"]["typ"] = "OPAQUE"

            # For text messages, we go ahead and decode the text to ascii for our users
            if asDict["decoded"]["data"]["typ"] == "CLEAR_TEXT":
                asDict["decoded"]["data"]["text"] = meshPacket.decoded.data.payload.decode(
                    "utf-8")

        pub.sendMessage(topic, packet=asDict, interface=self)


# Our standard BLE characteristics
TORADIO_UUID = "f75c76d2-129e-4dad-a1dd-7866124401e7"
FROMRADIO_UUID = "8ba2bcc2-ee02-4a55-a531-c525c5e454d5"
FROMNUM_UUID = "ed9da18c-a800-4f66-a670-aa7547e34453"


class BLEInterface(MeshInterface):
    """A not quite ready - FIXME - BLE interface to devices"""

    def __init__(self, address, debugOut=None):
        self.address = address
        self.adapter = pygatt.GATTToolBackend()  # BGAPIBackend()
        self.adapter.start()
        logging.debug(f"Connecting to {self.address}")
        self.device = self.adapter.connect(address)
        logging.debug("Connected to device")
        # fromradio = self.device.char_read(FROMRADIO_UUID)
        MeshInterface.__init__(self, debugOut=debugOut)

        self._readFromRadio()  # read the initial responses

        def handle_data(handle, data):
            self._handleFromRadio(data)

        self.device.subscribe(FROMNUM_UUID, callback=handle_data)

    def _sendToRadio(self, toRadio):
        """Send a ToRadio protobuf to the device"""
        logging.debug(f"Sending: {toRadio}")
        b = toRadio.SerializeToString()
        self.device.char_write(TORADIO_UUID, b)

    def close(self):
        self.adapter.stop()

    def _readFromRadio(self):
        wasEmpty = False
        while not wasEmpty:
            b = self.device.char_read(FROMRADIO_UUID)
            wasEmpty = len(b) == 0
            if not wasEmpty:
                self._handleFromRadio(b)


class StreamInterface(MeshInterface):
    """Interface class for meshtastic devices over a stream link (serial, TCP, etc)"""

    def __init__(self, devPath=None, debugOut=None, noProto=False, connectNow=True):
        """Constructor, opens a connection to a specified serial port, or if unspecified try to
        find one Meshtastic device by probing

        Keyword Arguments:
            devPath {string} -- A filepath to a device, i.e. /dev/ttyUSB0 (default: {None})
            debugOut {stream} -- If a stream is provided, any debug serial output from the device will be emitted to that stream. (default: {None})

        Raises:
            Exception: [description]
            Exception: [description]
        """

        if devPath is None:
            ports = util.findPorts()
            if len(ports) == 0:
                raise Exception("No Meshtastic devices detected")
            elif len(ports) > 1:
                raise Exception(
                    f"Multiple ports detected, you must specify a device, such as {ports[0].device}")
            else:
                devPath = ports[0]

        logging.debug(f"Connecting to {devPath}")
        self.devPath = devPath
        self._rxBuf = bytes()  # empty
        self._wantExit = False

        # Note: we provide None for port here, because we will be opening it later
        self.stream = serial.Serial(
            None, 921600, exclusive=True, timeout=0.5)

        # rts=False Needed to prevent TBEAMs resetting on OSX, because rts is connected to reset
        self.stream.port = devPath
        # OS-X seems to have a bug in its serial driver.  It ignores that we asked for no RTSCTS
        # control and will always drive RTS either high or low (rather than letting the CP102 leave
        # it as an open-collector floating pin).  Since it is going to drive it anyways we want to make
        # sure it is driven low, so that the TBEAM won't reset
        if platform.system() == 'Darwin':
            self.stream.rts = False
        self.stream.open()

        self._rxThread = threading.Thread(target=self.__reader, args=())

        MeshInterface.__init__(self, debugOut=debugOut, noProto=noProto)

        # Start the reader thread after superclass constructor completes init
        if connectNow:
            self.connect()

    def connect(self):
        """Connect to our radio

        Normally this is called automatically by the constructor, but if you passed in connectNow=False you can manually
        start the reading thread later.
        """

        # Send some bogus UART characters to force a sleeping device to wake
        self.stream.write(bytes([START1, START1, START1, START1]))
        self.stream.flush()
        time.sleep(0.1)  # wait 100ms to give device time to start running

        self._rxThread.start()

    def _sendToRadio(self, toRadio):
        """Send a ToRadio protobuf to the device"""
        logging.debug(f"Sending: {toRadio}")
        b = toRadio.SerializeToString()
        bufLen = len(b)
        header = bytes([START1, START2, (bufLen >> 8) & 0xff,  bufLen & 0xff])
        self.stream.write(header)
        self.stream.write(b)
        self.stream.flush()

    def close(self):
        """Close a connection to the device"""
        logging.debug("Closing serial stream")
        # pyserial cancel_read doesn't seem to work, therefore we ask the reader thread to close things for us
        self._wantExit = True
        if self._rxThread != threading.current_thread():
            self._rxThread.join()  # wait for it to exit

    def __reader(self):
        """The reader thread that reads bytes from our stream"""
        empty = bytes()

        try:
            while not self._wantExit:
                b = self.stream.read(1)
                if len(b) > 0:
                    # logging.debug(f"read returned {b}")
                    c = b[0]
                    ptr = len(self._rxBuf)

                    # Assume we want to append this byte, fixme use bytearray instead
                    self._rxBuf = self._rxBuf + b

                    if ptr == 0:  # looking for START1
                        if c != START1:
                            self._rxBuf = empty  # failed to find start
                            if self.debugOut != None:
                                try:
                                    self.debugOut.write(b.decode("utf-8"))
                                except:
                                    self.debugOut.write('?')

                    elif ptr == 1:  # looking for START2
                        if c != START2:
                            self._rxBuf = empty  # failed to find start2
                    elif ptr >= HEADER_LEN:  # we've at least got a header
                        # big endian length follos header
                        packetlen = (self._rxBuf[2] << 8) + self._rxBuf[3]

                        if ptr == HEADER_LEN:  # we _just_ finished reading the header, validate length
                            if packetlen > MAX_TO_FROM_RADIO_SIZE:
                                self._rxBuf = empty  # length ws out out bounds, restart

                        if len(self._rxBuf) != 0 and ptr + 1 == packetlen + HEADER_LEN:
                            try:
                                self._handleFromRadio(self._rxBuf[HEADER_LEN:])
                            except Exception as ex:
                                logging.error(
                                    f"Error while handling message from radio {ex}")
                                traceback.print_exc()
                            self._rxBuf = empty
                else:
                    # logging.debug(f"timeout on {self.devPath}")
                    pass
        except serial.SerialException as ex:
            logging.warn(
                f"Meshtastic serial port disconnected, disconnecting... {ex}")
        finally:
            logging.debug("reader is exiting")
            if platform.system() == 'Darwin':
                self.stream.rts = True  # Return RTS high, so that the reset button still works
            self.stream.close()
            self._disconnected()
