import importlib
import os
import signal
import struct
import time
import subprocess
from typing import Optional, List, ValuesView
from abc import ABC, abstractmethod
from multiprocessing import Process

from setproctitle import setproctitle  # pylint: disable=no-name-in-module

import cereal.messaging as messaging
import selfdrive.sentry as sentry
from common.basedir import BASEDIR
from common.params import Params
from common.realtime import sec_since_boot
from selfdrive.swaglog import cloudlog
from selfdrive.hardware import HARDWARE
from cereal import log

WATCHDOG_FN = "/dev/shm/wd_"
ENABLE_WATCHDOG = os.getenv("NO_WATCHDOG") is None


def launcher(proc: str, name: str) -> None:
  try:
    # import the process
    mod = importlib.import_module(proc)

    # rename the process
    setproctitle(proc)

    # create new context since we forked
    messaging.context = messaging.Context()

    # add daemon name tag to logs
    cloudlog.bind(daemon=name)
    sentry.set_tag("daemon", name)

    # exec the process
    getattr(mod, 'main')()
  except KeyboardInterrupt:
    cloudlog.warning(f"child {proc} got SIGINT")
  except Exception:
    # can't install the crash handler because sys.excepthook doesn't play nice
    # with threads, so catch it here.
    sentry.capture_exception()
    raise


def nativelauncher(pargs: List[str], cwd: str, name: str) -> None:
  os.environ['MANAGER_DAEMON'] = name

  # exec the process
  os.chdir(cwd)
  os.execvp(pargs[0], pargs)


def join_process(process: Process, timeout: float) -> None:
  # Process().join(timeout) will hang due to a python 3 bug: https://bugs.python.org/issue28382
  # We have to poll the exitcode instead
  t = time.monotonic()
  while time.monotonic() - t < timeout and process.exitcode is None:
    time.sleep(0.001)


class ManagerProcess(ABC):
  unkillable = False
  daemon = False
  sigkill = False
  persistent = False
  driverview = False
  proc: Optional[Process] = None
  enabled = True
  name = ""

  last_watchdog_time = 0
  watchdog_max_dt = None
  watchdog_seen = False
  shutting_down = False

  @abstractmethod
  def prepare(self) -> None:
    pass

  @abstractmethod
  def start(self) -> None:
    pass

  def restart(self) -> None:
    self.stop()
    self.start()

  def check_watchdog(self, started: bool) -> None:
    if self.watchdog_max_dt is None or self.proc is None:
      return

    try:
      fn = WATCHDOG_FN + str(self.proc.pid)
      # TODO: why can't pylint find struct.unpack?
      self.last_watchdog_time = struct.unpack('Q', open(fn, "rb").read())[0] # pylint: disable=no-member
    except Exception:
      pass

    dt = sec_since_boot() - self.last_watchdog_time / 1e9

    if dt > self.watchdog_max_dt:
      # Only restart while offroad for now
      if self.watchdog_seen and ENABLE_WATCHDOG:
        cloudlog.error(f"Watchdog timeout for {self.name} (exitcode {self.proc.exitcode}) restarting ({started=})")
        self.restart()
    else:
      self.watchdog_seen = True

  def stop(self, retry: bool=True, block: bool=True) -> Optional[int]:
    if self.proc is None:
      return None

    if self.proc.exitcode is None:
      if not self.shutting_down:
        cloudlog.info(f"killing {self.name}")
        sig = signal.SIGKILL if self.sigkill else signal.SIGINT
        self.signal(sig)
        self.shutting_down = True

        if not block:
          return None

      join_process(self.proc, 5)

      # If process failed to die send SIGKILL or reboot
      if self.proc.exitcode is None and retry:
        if self.unkillable:
          cloudlog.critical(f"unkillable process {self.name} failed to exit! rebooting in 15 if it doesn't die")
          join_process(self.proc, 15)

          if self.proc.exitcode is None:
            cloudlog.critical(f"unkillable process {self.name} failed to die!")
            os.system("date >> /data/unkillable_reboot")
            os.sync()
            HARDWARE.reboot()
            raise RuntimeError
        else:
          cloudlog.info(f"killing {self.name} with SIGKILL")
          self.signal(signal.SIGKILL)
          self.proc.join()

    ret = self.proc.exitcode
    cloudlog.info(f"{self.name} is dead with {ret}")

    if self.proc.exitcode is not None:
      self.shutting_down = False
      self.proc = None

    return ret

  def signal(self, sig: int) -> None:
    if self.proc is None:
      return

    # Don't signal if already exited
    if self.proc.exitcode is not None and self.proc.pid is not None:
      return

    # Can't signal if we don't have a pid
    if self.proc.pid is None:
      return

    cloudlog.info(f"sending signal {sig} to {self.name}")
    os.kill(self.proc.pid, sig)

  def get_process_state_msg(self):
    state = log.ManagerState.ProcessState.new_message()
    state.name = self.name
    if self.proc:
      state.running = self.proc.is_alive()
      state.shouldBeRunning = self.proc is not None and not self.shutting_down
      state.pid = self.proc.pid or 0
      state.exitCode = self.proc.exitcode or 0
    return state


class NativeProcess(ManagerProcess):
  def __init__(self, name, cwd, cmdline, enabled=True, persistent=False, driverview=False, unkillable=False, sigkill=False, watchdog_max_dt=None):
    self.name = name
    self.cwd = cwd
    self.cmdline = cmdline
    self.enabled = enabled
    self.persistent = persistent
    self.driverview = driverview
    self.unkillable = unkillable
    self.sigkill = sigkill
    self.watchdog_max_dt = watchdog_max_dt

  def prepare(self) -> None:
    pass

  def start(self) -> None:
    # In case we only tried a non blocking stop we need to stop it before restarting
    if self.shutting_down:
      self.stop()

    if self.proc is not None:
      return

    cwd = os.path.join(BASEDIR, self.cwd)
    cloudlog.info(f"starting process {self.name}")
    self.proc = Process(name=self.name, target=nativelauncher, args=(self.cmdline, cwd, self.name))
    self.proc.start()
    self.watchdog_seen = False
    self.shutting_down = False


class PythonProcess(ManagerProcess):
  def __init__(self, name, module, enabled=True, persistent=False, driverview=False, unkillable=False, sigkill=False, watchdog_max_dt=None):
    self.name = name
    self.module = module
    self.enabled = enabled
    self.persistent = persistent
    self.driverview = driverview
    self.unkillable = unkillable
    self.sigkill = sigkill
    self.watchdog_max_dt = watchdog_max_dt

  def prepare(self) -> None:
    if self.enabled:
      cloudlog.info(f"preimporting {self.module}")
      importlib.import_module(self.module)

  def start(self) -> None:
    # In case we only tried a non blocking stop we need to stop it before restarting
    if self.shutting_down:
      self.stop()

    if self.proc is not None:
      return

    cloudlog.info(f"starting python {self.module}")
    self.proc = Process(name=self.name, target=launcher, args=(self.module, self.name))
    self.proc.start()
    self.watchdog_seen = False
    self.shutting_down = False


class DaemonProcess(ManagerProcess):
  """Python process that has to stay running across manager restart.
  This is used for athena so you don't lose SSH access when restarting manager."""
  def __init__(self, name, module, param_name, enabled=True):
    self.name = name
    self.module = module
    self.param_name = param_name
    self.enabled = enabled
    self.persistent = True

  def prepare(self) -> None:
    pass

  def start(self) -> None:
    params = Params()
    pid = params.get(self.param_name, encoding='utf-8')

    if pid is not None:
      try:
        os.kill(int(pid), 0)
        with open(f'/proc/{pid}/cmdline') as f:
          if self.module in f.read():
            # daemon is running
            return
      except (OSError, FileNotFoundError):
        # process is dead
        pass

    cloudlog.info(f"starting daemon {self.name}")
    proc = subprocess.Popen(['python', '-m', self.module],  # pylint: disable=subprocess-popen-preexec-fn
                               stdin=open('/dev/null'),
                               stdout=open('/dev/null', 'w'),
                               stderr=open('/dev/null', 'w'),
                               preexec_fn=os.setpgrp)

    params.put(self.param_name, str(proc.pid))

  def stop(self, retry=True, block=True) -> None:
    pass


def ensure_running(procs: ValuesView[ManagerProcess], started: bool, driverview: bool=False, not_run: Optional[List[str]]=None) -> None:
  if not_run is None:
    not_run = []

  for p in procs:
    if p.name in not_run:
      p.stop(block=False)
    elif not p.enabled:
      p.stop(block=False)
    elif p.persistent:
      p.start()
    elif p.driverview and driverview:
      p.start()
    elif started:
      p.start()
    else:
      p.stop(block=False)

    p.check_watchdog(started)