import asyncio
import asyncio.subprocess
import socket
import dataclasses
import json
from typing import Any

import netifaces

from ... import tools
from ... import aiotools
from ... import aioproc

from ...logging import get_logger

from .stun import StunNatType
from .stun import Stun


# =====
@dataclasses.dataclass(frozen=True)
class _Netcfg:
    nat_type:  StunNatType = dataclasses.field(default=StunNatType.ERROR)
    src_ip:    str = dataclasses.field(default="")
    ext_ip:    str = dataclasses.field(default="")
    stun_host: str = dataclasses.field(default="")
    stun_ip:   str = dataclasses.field(default="")
    stun_port: int = dataclasses.field(default=0)


# =====
class JanusRunner:  # pylint: disable=too-many-instance-attributes
    def __init__(  # pylint: disable=too-many-arguments
        self,
        stun_host: str,
        stun_port: int,
        stun_timeout: float,
        stun_retries: int,
        stun_retries_delay: float,

        check_interval: int,
        check_retries: int,
        check_retries_delay: float,

        cmd: list[str],
        cmd_remove: list[str],
        cmd_append: list[str],
        ice_servers: list[dict[str, Any]],
    ) -> None:

        self.__stun = Stun(stun_host, stun_port, stun_timeout, stun_retries, stun_retries_delay)

        self.__check_interval = check_interval
        self.__check_retries = check_retries
        self.__check_retries_delay = check_retries_delay

        self.__cmd = tools.build_cmd(cmd, cmd_remove, cmd_append)
        self.__ice_servers = ice_servers

        self.__janus_task: (asyncio.Task | None) = None
        self.__janus_proc: (asyncio.subprocess.Process | None) = None  # pylint: disable=no-member

    def run(self) -> None:
        logger = get_logger(0)
        logger.info("Starting Janus Runner ...")
        aiotools.run(self.__run(), self.__stop_janus())
        logger.info("Bye-bye")

    # =====

    async def __run(self) -> None:
        logger = get_logger(0)
        logger.info("Probbing the network first time ...")

        prev_netcfg: (_Netcfg | None) = None
        while True:
            retry = 0
            netcfg = _Netcfg()
            for retry in range(1 if prev_netcfg is None else self.__check_retries):
                netcfg = await self.__get_netcfg()
                if netcfg.ext_ip:
                    break
                await asyncio.sleep(self.__check_retries_delay)
            if retry != 0 and netcfg.ext_ip:
                logger.info("I'm fine, continue working ...")

            if netcfg != prev_netcfg:
                logger.info("Got new %s", netcfg)
                if netcfg.src_ip:
                    await self.__stop_janus()
                    await self.__start_janus(netcfg)
                else:
                    logger.error("Empty src_ip; stopping Janus ...")
                    await self.__stop_janus()
                prev_netcfg = netcfg

            await asyncio.sleep(self.__check_interval)

    async def __get_netcfg(self) -> _Netcfg:
        src_ip = (self.__get_default_ip() or "0.0.0.0")
        info = await self.__stun.get_info(src_ip, 0)
        # В текущей реализации _Netcfg() это копия StunInfo()
        return _Netcfg(**dataclasses.asdict(info))

    def __get_default_ip(self) -> str:
        try:
            gws = netifaces.gateways()
            if "default" in gws:
                for proto in [socket.AF_INET, socket.AF_INET6]:
                    if proto in gws["default"]:
                        iface = gws["default"][proto][1]
                        addrs = netifaces.ifaddresses(iface)
                        return addrs[proto][0]["addr"]

            for iface in netifaces.interfaces():
                if not iface.startswith(("lo", "docker")):
                    addrs = netifaces.ifaddresses(iface)
                    for proto in [socket.AF_INET, socket.AF_INET6]:
                        if proto in addrs:
                            return addrs[proto][0]["addr"]
        except Exception as ex:
            get_logger().error("Can't get default IP: %s", tools.efmt(ex))
        return ""

    # =====

    @aiotools.atomic_fg
    async def __start_janus(self, netcfg: _Netcfg) -> None:
        get_logger(0).info("Starting Janus ...")
        assert not self.__janus_task
        self.__janus_task = asyncio.create_task(self.__janus_task_loop(netcfg))

    @aiotools.atomic_fg
    async def __stop_janus(self) -> None:
        if self.__janus_task:
            get_logger(0).info("Stopping Janus ...")
            self.__janus_task.cancel()
            await asyncio.gather(self.__janus_task, return_exceptions=True)
        await self.__kill_janus_proc()
        self.__janus_task = None

    # =====

    async def __janus_task_loop(self, netcfg: _Netcfg) -> None:  # pylint: disable=too-many-branches
        logger = get_logger(0)
        while True:  # pylint: disable=too-many-nested-blocks
            try:
                await self.__start_janus_proc(netcfg)
                assert self.__janus_proc is not None
                await aioproc.log_stdout_infinite(self.__janus_proc, logger)
                raise RuntimeError("Janus unexpectedly died")
            except asyncio.CancelledError:
                break
            except Exception:
                if self.__janus_proc:
                    logger.exception("Unexpected Janus error: pid=%d", self.__janus_proc.pid)
                else:
                    logger.exception("Can't start Janus")
                await self.__kill_janus_proc()
                await asyncio.sleep(1)

    async def __start_janus_proc(self, netcfg: _Netcfg) -> None:
        assert self.__janus_proc is None
        placeholders = {
            "o_stun_server": f"--stun-server={netcfg.stun_ip}:{netcfg.stun_port}",
            **{
                key: str(value)
                for (key, value) in dataclasses.asdict(netcfg).items()
            },
        }
        cmd = list(self.__cmd)
        if not netcfg.ext_ip:
            placeholders["o_stun_server"] = ""
            while "{o_stun_server}" in cmd:
                cmd.remove("{o_stun_server}")
        cmd = [
            part.format(**placeholders)
            for part in cmd
        ]
        env = {}
        ice_payload = self.__build_ice_payload(netcfg)
        if ice_payload:
            env["JANUS_USTREAMER_WEB_ICE_URL"] = ice_payload
        self.__janus_proc = await aioproc.run_process(cmd=cmd, env=env or None)
        get_logger(0).info("Started Janus pid=%d: %s", self.__janus_proc.pid, tools.cmdfmt(cmd))

    async def __kill_janus_proc(self) -> None:
        if self.__janus_proc:
            await aioproc.kill_process(self.__janus_proc, 5, get_logger(0))
        self.__janus_proc = None

    def __build_ice_payload(self, netcfg: _Netcfg) -> (str | None):
        if self.__ice_servers:
            try:
                return f"json:{json.dumps(self.__ice_servers, ensure_ascii=False)}"
            except Exception as ex:  # pragma: no cover
                get_logger(0).error("Can't encode ICE servers: %s", tools.efmt(ex))
                return None
        if netcfg.stun_host and netcfg.stun_port:
            return f"stun:{netcfg.stun_host}:{netcfg.stun_port}"
        return None