# coding=utf-8

import os
import platform
import signal
import subprocess
import sys
import time

from bazarr.get_args import args
from libs.six import PY3


def check_python_version():
    python_version = platform.python_version_tuple()
    minimum_py2_tuple = (2, 7, 13)
    minimum_py3_tuple = (3, 7, 0)
    minimum_py2_str = ".".join(str(i) for i in minimum_py2_tuple)
    minimum_py3_str = ".".join(str(i) for i in minimum_py3_tuple)

    if int(python_version[0]) < 3:
        print("Python " + minimum_py3_str + " or greater required. "
              "Current version is " + platform.python_version() + ". Please upgrade Python.")
        sys.exit(1)
    elif (int(python_version[0]) == minimum_py3_tuple[0] and int(python_version[1]) < minimum_py3_tuple[1]) or \
            (int(python_version[0]) != minimum_py3_tuple[0] and int(python_version[0]) != minimum_py2_tuple[0]):
        print("Python " + minimum_py3_str + " or greater required. "
              "Current version is " + platform.python_version() + ". Please upgrade Python.")
        sys.exit(1)


check_python_version()

dir_name = os.path.dirname(__file__)


class ProcessRegistry:

    def register(self, process):
        pass

    def unregister(self, process):
        pass


class DaemonStatus(ProcessRegistry):

    def __init__(self):
        self.__should_stop = False
        self.__processes = set()

    def register(self, process):
        self.__processes.add(process)

    def unregister(self, process):
        self.__processes.remove(process)

    @staticmethod
    def __send_signal(processes, signal_no, live_processes=None):
        """
        Sends to every single of the specified processes the given signal and (if live_processes is not None) append to
        it processes which are still alive.
        """
        for ep in processes:
            if ep.poll() is None:
                if live_processes is not None:
                    live_processes.append(ep)
                try:
                    ep.send_signal(signal_no)
                except Exception as e:
                    print('Failed sending signal %s to process %s because of an unexpected error: %s' % (
                        signal_no, ep.pid, e))
        return live_processes

    def stop(self):
        """
        Flags this instance as should stop and terminates as smoothly as possible children processes.
        """
        self.__should_stop = True
        DaemonStatus.__send_signal(self.__processes, signal.SIGINT, list())

    def force_stop(self):
        self.__should_stop = True
        DaemonStatus.__send_signal(self.__processes, signal.SIGTERM)

    def should_stop(self):
        return self.__should_stop


def start_bazarr(process_registry=ProcessRegistry()):
    script = [sys.executable, "-u", os.path.normcase(os.path.join(dir_name, 'bazarr', 'main.py'))] + sys.argv[1:]

    print("Bazarr starting...")
    if PY3:
        ep = subprocess.Popen(script, stdout=None, stderr=None, stdin=subprocess.DEVNULL)
    else:
        ep = subprocess.Popen(script, stdout=None, stderr=None, stdin=None)
    process_registry.register(ep)
    try:
        ep.wait()
        process_registry.unregister(ep)
    except KeyboardInterrupt:
        pass


if __name__ == '__main__':
    restartfile = os.path.normcase(os.path.join(args.config_dir, 'bazarr.restart'))
    stopfile = os.path.normcase(os.path.join(args.config_dir, 'bazarr.stop'))

    try:
        os.remove(restartfile)
    except Exception:
        pass

    try:
        os.remove(stopfile)
    except Exception:
        pass


    def daemon(bazarr_runner=lambda: start_bazarr()):
        if os.path.exists(stopfile):
            try:
                os.remove(stopfile)
            except Exception:
                print('Unable to delete stop file.')
            else:
                print('Bazarr exited.')
                sys.exit(0)

        if os.path.exists(restartfile):
            try:
                os.remove(restartfile)
            except Exception:
                print('Unable to delete restart file.')
            else:
                bazarr_runner()


    bazarr_runner = lambda: start_bazarr()

    should_stop = lambda: False

    if PY3:
        daemonStatus = DaemonStatus()

        def force_shutdown():
            # force the killing of children processes
            daemonStatus.force_stop()
            # if a new SIGTERM signal is caught the standard behaviour should be followed
            signal.signal(signal.SIGTERM, signal.SIG_DFL)
            # emulate a Ctrl C command on itself (bypasses the signal thing but, then, emulates the "Ctrl+C break")
            os.kill(os.getpid(), signal.SIGINT)
    
        def shutdown():
            # indicates that everything should stop
            daemonStatus.stop()
            # if a new sigterm signal is caught it should force the shutdown of children processes
            signal.signal(signal.SIGTERM, lambda signal_no, frame: force_shutdown())

        signal.signal(signal.SIGTERM, lambda signal_no, frame: shutdown())

        should_stop = lambda: daemonStatus.should_stop()
        bazarr_runner = lambda: start_bazarr(daemonStatus)

    bazarr_runner()

    # Keep the script running forever until stop is requested through term or keyboard interrupt
    while not should_stop():
        daemon(bazarr_runner)
        time.sleep(1)