import logging
import threading
import time
import random
import socket
from owrx.config import PropertyManager
from owrx.version import openwebrx_version
from owrx.locator import Locator

logger = logging.getLogger(__name__)


class PskReporterDummy(object):
    """
    used in place of the PskReporter when reporting is disabled.
    does nothing.
    """

    def spot(self, spot):
        pass

    def cancelTimer(self):
        pass


class PskReporter(object):
    sharedInstance = None
    creationLock = threading.Lock()
    interval = 300
    supportedModes = ["FT8", "FT4", "JT9", "JT65"]

    @staticmethod
    def getSharedInstance():
        with PskReporter.creationLock:
            if PskReporter.sharedInstance is None:
                if PropertyManager.getSharedInstance()["pskreporter_enabled"]:
                    PskReporter.sharedInstance = PskReporter()
                else:
                    PskReporter.sharedInstance = PskReporterDummy()
        return PskReporter.sharedInstance

    @staticmethod
    def stop():
        if PskReporter.sharedInstance:
            PskReporter.sharedInstance.cancelTimer()

    def __init__(self):
        self.spots = []
        self.spotLock = threading.Lock()
        self.uploader = Uploader()
        self.timer = None

    def scheduleNextUpload(self):
        if self.timer:
            return
        delay = PskReporter.interval + random.uniform(0, 30)
        logger.debug("scheduling next pskreporter upload in %f seconds", delay)
        self.timer = threading.Timer(delay, self.upload)
        self.timer.start()

    def spot(self, spot):
        if not spot["mode"] in PskReporter.supportedModes:
            return
        with self.spotLock:
            self.spots.append(spot)
        self.scheduleNextUpload()

    def upload(self):
        try:
            with self.spotLock:
                spots = self.spots
                self.spots = []

            if spots:
                self.uploader.upload(spots)
        except Exception:
            logger.exception("Failed to upload spots")

        self.timer = None
        self.scheduleNextUpload()

    def cancelTimer(self):
        if self.timer:
            self.timer.cancel()


class Uploader(object):
    receieverDelimiter = [0x99, 0x92]
    senderDelimiter = [0x99, 0x93]

    def __init__(self):
        self.sequence = 0
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    def upload(self, spots):
        logger.debug("uploading %i spots", len(spots))
        for packet in self.getPackets(spots):
            self.socket.sendto(packet, ("report.pskreporter.info", 4739))

    def getPackets(self, spots):
        encoded = [self.encodeSpot(spot) for spot in spots]

        def chunks(l, n):
            """Yield successive n-sized chunks from l."""
            for i in range(0, len(l), n):
                yield l[i : i + n]

        rHeader = self.getReceiverInformationHeader()
        rInfo = self.getReceiverInformation()
        sHeader = self.getSenderInformationHeader()

        packets = []
        # 50 seems to be a safe bet
        for chunk in chunks(encoded, 50):
            sInfo = self.getSenderInformation(chunk)
            length = 16 + len(rHeader) + len(sHeader) + len(rInfo) + len(sInfo)
            header = self.getHeader(length)
            packets.append(header + rHeader + sHeader + rInfo + sInfo)

        return packets

    def getHeader(self, length):
        self.sequence += 1
        return bytes(
            # protocol version
            [0x00, 0x0A]
            + list(length.to_bytes(2, "big"))
            + list(int(time.time()).to_bytes(4, "big"))
            + list(self.sequence.to_bytes(4, "big"))
            + list((id(self) & 0xFFFFFFFF).to_bytes(4, "big"))
        )

    def encodeString(self, s):
        return [len(s)] + list(s.encode("utf-8"))

    def encodeSpot(self, spot):
        return bytes(
            self.encodeString(spot["callsign"])
            + list(spot["freq"].to_bytes(4, "big"))
            + list(int(spot["db"]).to_bytes(1, "big", signed=True))
            + self.encodeString(spot["mode"])
            + self.encodeString(spot["locator"])
            # informationsource. 1 means "automatically extracted
            + [0x01]
            + list(int(spot["timestamp"] / 1000).to_bytes(4, "big"))
        )

    def getReceiverInformationHeader(self):
        return bytes(
            # id, length
            [0x00, 0x03, 0x00, 0x24]
            + Uploader.receieverDelimiter
            # number of fields
            + [0x00, 0x03, 0x00, 0x00]
            # receiverCallsign
            + [0x80, 0x02, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # receiverLocator
            + [0x80, 0x04, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # decodingSoftware
            + [0x80, 0x08, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # padding
            + [0x00, 0x00]
        )

    def getReceiverInformation(self):
        pm = PropertyManager.getSharedInstance()
        callsign = pm["pskreporter_callsign"]
        locator = Locator.fromCoordinates(pm["receiver_gps"])
        decodingSoftware = "OpenWebRX " + openwebrx_version
        body = [b for s in [callsign, locator, decodingSoftware] for b in self.encodeString(s)]
        body = self.pad(body, 4)
        body = bytes(Uploader.receieverDelimiter + list((len(body) + 4).to_bytes(2, "big")) + body)
        return body

    def getSenderInformationHeader(self):
        return bytes(
            # id, length
            [0x00, 0x02, 0x00, 0x3C]
            + Uploader.senderDelimiter
            # number of fields
            + [0x00, 0x07]
            # senderCallsign
            + [0x80, 0x01, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # frequency
            + [0x80, 0x05, 0x00, 0x04, 0x00, 0x00, 0x76, 0x8F]
            # sNR
            + [0x80, 0x06, 0x00, 0x01, 0x00, 0x00, 0x76, 0x8F]
            # mode
            + [0x80, 0x0A, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # senderLocator
            + [0x80, 0x03, 0xFF, 0xFF, 0x00, 0x00, 0x76, 0x8F]
            # informationSource
            + [0x80, 0x0B, 0x00, 0x01, 0x00, 0x00, 0x76, 0x8F]
            # flowStartSeconds
            + [0x00, 0x96, 0x00, 0x04]
        )

    def getSenderInformation(self, chunk):
        sInfo = self.padBytes(b"".join(chunk), 4)
        sInfoLength = len(sInfo) + 4
        return bytes(Uploader.senderDelimiter) + sInfoLength.to_bytes(2, "big") + sInfo

    def pad(self, b, l):
        return b + [0x00 for _ in range(0, -1 * len(b) % l)]

    def padBytes(self, b, l):
        return b + bytes([0x00 for _ in range(0, -1 * len(b) % l)])