from abc import ABC, ABCMeta, abstractmethod
from owrx.config import Config
from owrx.metrics import Metrics, CounterMetric, DirectMetric
import threading
import wave
import subprocess
import os
from multiprocessing.connection import Pipe, wait
from datetime import datetime, timedelta
from queue import Queue, Full, Empty


import logging

logger = logging.getLogger(__name__)
logger.setLevel(logging.INFO)


class QueueJob(object):
    def __init__(self, decoder, file, freq):
        self.decoder = decoder
        self.file = file
        self.freq = freq

    def run(self):
        self.decoder.decode(self)

    def unlink(self):
        try:
            os.unlink(self.file)
        except FileNotFoundError:
            pass


PoisonPill = object()


class QueueWorker(threading.Thread):
    def __init__(self, queue):
        self.queue = queue
        self.doRun = True
        super().__init__()

    def run(self) -> None:
        while self.doRun:
            job = self.queue.get()
            if job is PoisonPill:
                self.doRun = False
                # put the poison pill back on the queue for the next worker
                self.queue.put(PoisonPill)
            else:
                try:
                    job.run()
                except Exception:
                    logger.exception("failed to decode job")
                    self.queue.onError()
                finally:
                    job.unlink()

            self.queue.task_done()


class DecoderQueue(Queue):
    sharedInstance = None
    creationLock = threading.Lock()

    @staticmethod
    def getSharedInstance():
        with DecoderQueue.creationLock:
            if DecoderQueue.sharedInstance is None:
                pm = Config.get()
                DecoderQueue.sharedInstance = DecoderQueue(maxsize=pm["decoding_queue_length"], workers=pm["decoding_queue_workers"])
        return DecoderQueue.sharedInstance

    @staticmethod
    def stopAll():
        with DecoderQueue.creationLock:
            if DecoderQueue.sharedInstance is not None:
                DecoderQueue.sharedInstance.stop()
                DecoderQueue.sharedInstance = None

    def __init__(self, maxsize, workers):
        super().__init__(maxsize)
        metrics = Metrics.getSharedInstance()
        metrics.addMetric("decoding.queue.length", DirectMetric(self.qsize))
        self.inCounter = CounterMetric()
        metrics.addMetric("decoding.queue.in", self.inCounter)
        self.outCounter = CounterMetric()
        metrics.addMetric("decoding.queue.out", self.outCounter)
        self.overflowCounter = CounterMetric()
        metrics.addMetric("decoding.queue.overflow", self.overflowCounter)
        self.errorCounter = CounterMetric()
        metrics.addMetric("decoding.queue.error", self.errorCounter)
        self.workers = [self.newWorker() for _ in range(0, workers)]

    def stop(self):
        logger.debug("shutting down the queue")
        try:
            # purge all remaining jobs
            while not self.empty():
                job = self.get()
                job.unlink()
        except Empty:
            pass
        # put() PoisonPill to tell workers to shut down
        self.put(PoisonPill)

    def put(self, item, **kwars):
        self.inCounter.inc()
        try:
            super(DecoderQueue, self).put(item, block=False)
        except Full:
            self.overflowCounter.inc()
            raise

    def get(self, **kwargs):
        # super.get() is blocking, so it would mess up the stats to inc() first
        out = super(DecoderQueue, self).get(**kwargs)
        self.outCounter.inc()
        return out

    def newWorker(self):
        worker = QueueWorker(self)
        worker.start()
        return worker

    def onError(self):
        self.errorCounter.inc()


class AudioChopperProfile(ABC):
    @abstractmethod
    def getInterval(self):
        pass

    @abstractmethod
    def getFileTimestampFormat(self):
        pass

    @abstractmethod
    def decoder_commandline(self, file):
        pass


class AudioWriter(object):
    def __init__(self, dsp, source, profile: AudioChopperProfile):
        self.dsp = dsp
        self.source = source
        self.profile = profile
        self.tmp_dir = Config.get()["temporary_directory"]
        self.wavefile = None
        self.wavefilename = None
        self.switchingLock = threading.Lock()
        self.timer = None
        (self.outputReader, self.outputWriter) = Pipe()

    def getWaveFile(self):
        filename = "{tmp_dir}/openwebrx-audiochopper-{id}-{timestamp}.wav".format(
            tmp_dir=self.tmp_dir,
            id=id(self),
            timestamp=datetime.utcnow().strftime(self.profile.getFileTimestampFormat()),
        )
        wavefile = wave.open(filename, "wb")
        wavefile.setnchannels(1)
        wavefile.setsampwidth(2)
        wavefile.setframerate(12000)
        return filename, wavefile

    def getNextDecodingTime(self):
        t = datetime.utcnow()
        zeroed = t.replace(minute=0, second=0, microsecond=0)
        delta = t - zeroed
        interval = self.profile.getInterval()
        seconds = (int(delta.total_seconds() / interval) + 1) * interval
        t = zeroed + timedelta(seconds=seconds)
        logger.debug("scheduling: {0}".format(t))
        return t

    def cancelTimer(self):
        if self.timer:
            self.timer.cancel()
            self.timer = None

    def _scheduleNextSwitch(self):
        self.cancelTimer()
        delta = self.getNextDecodingTime() - datetime.utcnow()
        self.timer = threading.Timer(delta.total_seconds(), self.switchFiles)
        self.timer.start()

    def switchFiles(self):
        with self.switchingLock:
            file = self.wavefile
            filename = self.wavefilename
            (self.wavefilename, self.wavefile) = self.getWaveFile()

        file.close()
        job = QueueJob(self, filename, self.dsp.get_operating_freq())
        try:
            DecoderQueue.getSharedInstance().put(job)
        except Full:
            logger.warning("decoding queue overflow; dropping one file")
            job.unlink()
        self._scheduleNextSwitch()

    def decode(self, job: QueueJob):
        logger.debug("processing file %s", job.file)
        decoder = subprocess.Popen(
            ["nice", "-n", "10"] + self.profile.decoder_commandline(job.file),
            stdout=subprocess.PIPE,
            cwd=self.tmp_dir,
            close_fds=True,
        )
        try:
            for line in decoder.stdout:
                self.outputWriter.send((self.profile, job.freq, line))
        except (OSError, AttributeError):
            decoder.stdout.flush()
            # TODO uncouple parsing from the output so that decodes can still go to the map and the spotters
            logger.debug("output has gone away while decoding job.")
        try:
            rc = decoder.wait(timeout=10)
            if rc != 0:
                raise RuntimeError("decoder return code: {0}".format(rc))
        except subprocess.TimeoutExpired:
            logger.warning("subprocess (pid=%i}) did not terminate correctly; sending kill signal.", decoder.pid)
            decoder.kill()
            raise

    def start(self):
        (self.wavefilename, self.wavefile) = self.getWaveFile()
        self._scheduleNextSwitch()

    def write(self, data):
        with self.switchingLock:
            self.wavefile.writeframes(data)

    def stop(self):
        self.outputWriter.close()
        self.outputWriter = None

        # drain messages left in the queue so that the queue can be successfully closed
        # this is necessary since python keeps the file descriptors open otherwise
        try:
            while True:
                self.outputReader.recv()
        except EOFError:
            pass
        self.outputReader.close()
        self.outputReader = None

        self.cancelTimer()
        try:
            self.wavefile.close()
        except Exception:
            logger.exception("error closing wave file")
        try:
            with self.switchingLock:
                os.unlink(self.wavefilename)
        except Exception:
            logger.exception("error removing undecoded file")
        self.wavefile = None
        self.wavefilename = None


class AudioChopper(threading.Thread, metaclass=ABCMeta):
    def __init__(self, dsp, source, *profiles: AudioChopperProfile):
        self.source = source
        self.writers = [AudioWriter(dsp, source, p) for p in profiles]
        self.doRun = True
        super().__init__()

    def run(self) -> None:
        logger.debug("Audio chopper starting up")
        for w in self.writers:
            w.start()
        while self.doRun:
            data = None
            try:
                data = self.source.read(256)
            except ValueError:
                pass
            if data is None or (isinstance(data, bytes) and len(data) == 0):
                self.doRun = False
            else:
                for w in self.writers:
                    w.write(data)

        logger.debug("Audio chopper shutting down")
        for w in self.writers:
            w.stop()

    def read(self):
        try:
            readers = wait([w.outputReader for w in self.writers])
            return [r.recv() for r in readers]
        except (EOFError, OSError):
            return None