import atexit
import logging
import os
import re
import signal
import subprocess

import psutil
import tzlocal
from django.template.loader import render_to_string
from django.utils import timezone as tz
from django.utils.translation import gettext_lazy as _

from aircox.conf import settings
from aircox.utils import to_seconds

from .connector import Connector

__all__ = [
    "BaseMetadata",
    "Request",
    "Streamer",
    "Source",
    "PlaylistSource",
    "QueueSource",
]

# TODO: for the moment, update in station and program names do not update the
#       related fields.

# FIXME liquidsoap does not manage timezones -- we have to convert
#       'on_air' metadata we get from it into utc one in order to work
#       correctly.

local_tz = tzlocal.get_localzone()
logger = logging.getLogger("aircox")


class BaseMetadata:
    """Base class for handling request metadata."""

    controller = None
    """Controller."""
    rid = None
    """Request id."""
    uri = None
    """Request uri."""
    status = None
    """Current playing status."""
    request_status = None
    """Requests' status."""
    air_time = None
    """Launch datetime."""

    def __init__(self, controller=None, rid=None, data=None):
        self.controller = controller
        self.rid = rid
        if data is not None:
            self.validate(data)

    @property
    def is_playing(self):
        return self.status == "playing"

    @property
    def status_verbose(self):
        return self.validate_status(self.status, True)

    def fetch(self):
        data = self.controller.send("request.metadata ", self.rid, parse=True)
        if data:
            self.validate(data)

    def validate_status(self, status, i18n=False):
        on_air = self.controller.source
        if (
            on_air
            and status == "playing"
            and (on_air == self or on_air.rid == self.rid)
        ):
            return _("playing") if i18n else "playing"
        elif status == "playing":
            return _("paused") if i18n else "paused"
        else:
            return _("stopped") if i18n else "stopped"

    def validate_air_time(self, air_time):
        if air_time:
            air_time = tz.datetime.strptime(air_time, "%Y/%m/%d %H:%M:%S")
            return local_tz.localize(air_time)

    def validate(self, data):
        """Validate provided data and set as attribute (must already be
        declared)"""
        for key, value in data.items():
            if hasattr(self, key) and not callable(getattr(self, key)):
                setattr(self, key, value)
        self.uri = data.get("initial_uri")

        self.air_time = self.validate_air_time(data.get("on_air"))
        self.status = self.validate_status(data.get("status"))
        self.request_status = data.get("status")


class Request(BaseMetadata):
    title = None
    artist = None


class Streamer:
    connector = None
    process = None

    station = None
    template_name = "aircox_streamer/scripts/station.liq"
    path = None
    """Config path."""
    sources = None
    """List of all monitored sources."""
    source = None
    """Current source being played on air."""
    # note: we disable on_air rids since we don't have use of it for the
    # moment
    # on_air = None
    # """ On-air request ids (rid) """
    inputs = None
    """Queryset to input ports."""
    outputs = None
    """Queryset to output ports."""

    def __init__(self, station, connector=None):
        self.station = station
        self.inputs = self.station.port_set.active().input()
        self.outputs = self.station.port_set.active().output()

        self.id = self.station.slug.replace("-", "_")
        self.path = os.path.join(station.path, "station.liq")
        self.connector = Connector(os.path.join(station.path, "station.sock"))
        self.init_sources()

    @property
    def socket_path(self):
        """Path to Unix socket file."""
        return self.connector.address

    @property
    def is_ready(self):
        """If external program is ready to use, returns True."""
        return self.send("list") != ""

    @property
    def is_running(self):
        """True if holds a running process."""
        if self.process is None:
            return False

        returncode = self.process.poll()
        if returncode is None:
            return True

        self.process = None
        logger.debug("process died with return code %s" % returncode)
        return False

    @property
    def playlists(self):
        return (s for s in self.sources if isinstance(s, PlaylistSource))

    @property
    def queues(self):
        return (s for s in self.sources if isinstance(s, QueueSource))

    # Sources and config ###############################################
    def send(self, *args, **kwargs):
        return self.connector.send(*args, **kwargs) or ""

    def init_sources(self):
        streams = self.station.program_set.filter(stream__isnull=False)
        self.dealer = QueueSource(self, "dealer")
        self.sources = [self.dealer] + [
            PlaylistSource(self, program=program) for program in streams
        ]

    def make_config(self):
        """Make configuration files and directory (and sync sources)"""
        data = render_to_string(
            self.template_name,
            {
                "station": self.station,
                "streamer": self,
                "settings": settings,
            },
        )
        data = re.sub("[\t ]+\n", "\n", data)
        data = re.sub("\n{3,}", "\n\n", data)

        os.makedirs(os.path.dirname(self.path), exist_ok=True)
        with open(self.path, "w+") as file:
            file.write(data)

        self.sync()

    def sync(self):
        """Sync all sources."""
        for source in self.sources:
            source.sync()

    def fetch(self):
        """Fetch data from liquidsoap."""
        for source in self.sources:
            source.fetch()

        # request.on_air is not ordered: we need to do it manually
        self.source = next(
            iter(
                sorted(
                    (
                        source
                        for source in self.sources
                        if source.request_status == "playing"
                        and source.air_time
                    ),
                    key=lambda o: o.air_time,
                    reverse=True,
                )
            ),
            None,
        )

    # Process ##########################################################
    def get_process_args(self):
        return ["liquidsoap", "-v", self.path]

    def check_zombie_process(self):
        if not os.path.exists(self.socket_path):
            return

        conns = [
            conn
            for conn in psutil.net_connections(kind="unix")
            if conn.laddr == self.socket_path
        ]
        for conn in conns:
            if conn.pid is not None:
                os.kill(conn.pid, signal.SIGKILL)

    def run_process(self):
        """Execute the external application with corresponding informations.

        This function must make sure that all needed files have been
        generated.
        """
        if self.process:
            return

        args = self.get_process_args()
        if not args:
            return

        self.check_zombie_process()
        self.process = subprocess.Popen(args, stderr=subprocess.STDOUT)
        atexit.register(lambda: self.kill_process())

    def kill_process(self):
        if self.process:
            logger.debug(
                "kill process %s: %s",
                self.process.pid,
                " ".join(self.get_process_args()),
            )
            self.process.kill()
            self.process = None

    def wait_process(self):
        """Wait for the process to terminate if there is a process."""
        if self.process:
            self.process.wait()
            self.process = None


class Source(BaseMetadata):
    controller = None
    """Parent controller."""
    id = None
    """Source id."""
    remaining = 0.0
    """Remaining time."""
    status = "stopped"

    @property
    def station(self):
        return self.controller.station

    def __init__(self, controller=None, id=None, *args, **kwargs):
        super().__init__(controller, *args, **kwargs)
        self.id = id

    def sync(self):
        """Synchronize what should be synchronized."""

    def fetch(self):
        try:
            data = self.controller.send(self.id, ".remaining")
            if data:
                self.remaining = float(data)
        except ValueError:
            self.remaining = None

        data = self.controller.send(self.id, ".get", parse=True)
        if data:
            self.validate(data if data and isinstance(data, dict) else {})

    def skip(self):
        """Skip the current source sound."""
        self.controller.send(self.id, ".skip")

    def restart(self):
        """Restart current sound."""
        # seek 10 hours back since there is not possibility to get current pos
        self.seek(-216000 * 10)

    def seek(self, n):
        """Seeks into the sound."""
        self.controller.send(self.id, ".seek ", str(n))


class PlaylistSource(Source):
    """Source handling playlists (program streams)"""

    path = None
    """Path to playlist."""
    program = None
    """Related program."""
    playlist = None
    """The playlist."""

    def __init__(self, controller, id=None, program=None, **kwargs):
        id = program.slug.replace("-", "_") if id is None else id
        self.program = program

        super().__init__(controller, id=id, **kwargs)
        self.path = os.path.join(self.station.path, self.id + ".m3u")

    def get_sound_queryset(self):
        """Get playlist's sounds queryset."""
        return self.program.sound_set.archive()

    def get_playlist(self):
        """Get playlist from db."""
        return self.get_sound_queryset().playlist()

    def write_playlist(self, playlist=[]):
        """Write playlist to file."""
        os.makedirs(os.path.dirname(self.path), exist_ok=True)
        with open(self.path, "w") as file:
            file.write("\n".join(playlist or []))

    def stream(self):
        """Return program's stream info if any (or None) as dict."""
        # used in templates
        # TODO: multiple streams
        stream = self.program.stream_set.all().first()
        if not stream or (not stream.begin and not stream.delay):
            return

        return {
            "begin": stream.begin.strftime("%Hh%M") if stream.begin else None,
            "end": stream.end.strftime("%Hh%M") if stream.end else None,
            "delay": to_seconds(stream.delay) if stream.delay else 0,
        }

    def sync(self):
        playlist = self.get_playlist()
        self.write_playlist(playlist)


class QueueSource(Source):
    queue = None
    """Source's queue (excluded on_air request)"""

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def push(self, *paths):
        """Add the provided paths to source's play queue."""
        for path in paths:
            self.controller.send(self.id, "_queue.push ", path)

    def fetch(self):
        super().fetch()
        queue = self.controller.send(self.id, "_queue.queue").strip()
        if not queue:
            self.queue = []
            return

        self.queue = queue.split(" ")

    @property
    def requests(self):
        """Queue as requests metadata."""
        requests = [Request(self.controller, rid) for rid in self.queue]
        for request in requests:
            request.fetch()
        return requests