"""

Provides a 'pyramid' command as a replacement to the 'start' command.

The reloading strategy is heavily inspired by (and partially copied from)

the pyramid script 'pserve'.

"""

import atexit

import errno

import os

import signal

import sys

import time

import threading

import subprocess

from cubicweb import BadCommandUsage, ExecutionError

from pyramid_cubicweb import make_cubicweb_application

import waitress

MAXFD = 1024

          'help': 'start server in the foreground.'}),

        ('reload',

         {'action': 'store_true',

          'help': 'Restart the server if any source file is changed'}),

        ('reload-interval',

         {'type': 'int', 'default': 1,

          'help': 'Interval, in seconds, between file modifications checks'}),

    _reloader_environ_key = 'CW_RELOADER_SHOULD_RUN'

    def debug(self, msg):

        print('DEBUG - %s' % msg)

    def info(self, msg):

        print('INFO - %s' % msg)

    def ordered_instances(self):

        instances = super(PyramidStartHandler, self).ordered_instances()

        if (self['debug'] or self['reload']) and len(instances) > 1:

            raise BadCommandUsage(

                '--debug and --reload can be used on a single instance only')

        return instances

    def quote_first_command_arg(self, arg):

        """

        There's a bug in Windows when running an executable that's

        located inside a path with a space in it.  This method handles

        that case, or on non-Windows systems or an executable with no

        spaces, it just leaves well enough alone.

        """

        if (sys.platform != 'win32' or ' ' not in arg):

            # Problem does not apply:

            return arg

        try:

            import win32api

        except ImportError:

            raise ValueError(

                "The executable %r contains a space, and in order to "

                "handle this issue you must have the win32api module "

                "installed" % arg)

        arg = win32api.GetShortPathName(arg)

        return arg

    def _remove_pid_file(self, written_pid, filename):

        current_pid = os.getpid()

        if written_pid != current_pid:

            # A forked process must be exiting, not the process that

            # wrote the PID file

            return

        if not os.path.exists(filename):

            return

        with open(filename) as f:

            content = f.read().strip()

        try:

            pid_in_file = int(content)

        except ValueError:

            pass

        else:

            if pid_in_file != current_pid:

                msg = "PID file %s contains %s, not expected PID %s"

                self.out(msg % (filename, pid_in_file, current_pid))

                return

        self.info("Removing PID file %s" % filename)

        try:

            os.unlink(filename)

            return

        except OSError as e:

            # Record, but don't give traceback

            self.out("Cannot remove PID file: (%s)" % e)

        # well, at least lets not leave the invalid PID around...

        try:

            with open(filename, 'w') as f:

                f.write('')

        except OSError as e:

            self.out('Stale PID left in file: %s (%s)' % (filename, e))

        else:

            self.out('Stale PID removed')

    def record_pid(self, pid_file):

        pid = os.getpid()

        self.debug('Writing PID %s to %s' % (pid, pid_file))

        with open(pid_file, 'w') as f:

            f.write(str(pid))

        atexit.register(

            self._remove_pid_file, pid, pid_file)

    def daemonize(self, pid_file):

        pid = live_pidfile(pid_file)

        if pid:

            raise ExecutionError(

                "Daemon is already running (PID: %s from PID file %s)"

                % (pid, pid_file))

        self.debug('Entering daemon mode')

        pid = os.fork()

        if pid:

            # The forked process also has a handle on resources, so we

            # *don't* want proper termination of the process, we just

            # want to exit quick (which os._exit() does)

            os._exit(0)

        # Make this the session leader

        os.setsid()

        # Fork again for good measure!

        pid = os.fork()

        if pid:

            os._exit(0)

        # @@: Should we set the umask and cwd now?

        import resource  # Resource usage information.

        maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]

        if (maxfd == resource.RLIM_INFINITY):

            maxfd = MAXFD

        # Iterate through and close all file descriptors.

        for fd in range(0, maxfd):

            try:

                os.close(fd)

            except OSError:  # ERROR, fd wasn't open to begin with (ignored)

                pass

        if (hasattr(os, "devnull")):

            REDIRECT_TO = os.devnull

        else:

            REDIRECT_TO = "/dev/null"

        os.open(REDIRECT_TO, os.O_RDWR)  # standard input (0)

        # Duplicate standard input to standard output and standard error.

        os.dup2(0, 1)  # standard output (1)

        os.dup2(0, 2)  # standard error (2)

    def restart_with_reloader(self):

        self.debug('Starting subprocess with file monitor')

        while True:

            args = [self.quote_first_command_arg(sys.executable)] + sys.argv

            new_environ = os.environ.copy()

            new_environ[self._reloader_environ_key] = 'true'

            proc = None

            try:

                try:

                    proc = subprocess.Popen(args, env=new_environ)

                    exit_code = proc.wait()

                    proc = None

                    print "Process exited with ", exit_code

                except KeyboardInterrupt:

                    self.info('^C caught in monitor process')

                    return 1

            finally:

                if proc is not None:

                    proc.terminate()

                    self.info(

                        'Waiting for the server to stop. Hit CTRL-C to exit')

                    exit_code = proc.wait()

            if exit_code != 3:

                return exit_code

            self.info('%s %s %s' % ('-' * 20, 'Restarting', '-' * 20))

    def set_needreload(self):

        self._needreload = True

    def install_reloader(self, poll_interval, extra_files):

        mon = Monitor(

            poll_interval=poll_interval, extra_files=extra_files,

            atexit=self.set_needreload)

        mon_thread = threading.Thread(target=mon.periodic_reload)

        mon_thread.daemon = True

        mon_thread.start()

        self._needreload = False

        if self['reload'] and not os.environ.get(self._reloader_environ_key):

            return self.restart_with_reloader()

        if self['reload']:

            _turn_sigterm_into_systemexit()

            self.debug('Running reloading file monitor')

            extra_files = [sys.argv[0], cwconfig.main_config_file()]

            self.install_reloader(self['reload-interval'], extra_files)

        if not self['reload'] and not self['debug']:

            self.daemonize(cwconfig['pid-file'])

            self.record_pid(cwconfig['pid-file'])

            waitress.serve(

                pyramid_config.make_wsgi_app(), host=host, port=port)

        if self._needreload:

            return 3

        return 0

def live_pidfile(pidfile):  # pragma: no cover

    """(pidfile:str) -> int | None

    Returns an int found in the named file, if there is one,

    and if there is a running process with that process id.

    Return None if no such process exists.

    """

    pid = read_pidfile(pidfile)

    if pid:

        try:

            os.kill(int(pid), 0)

            return pid

        except OSError as e:

            if e.errno == errno.EPERM:

                return pid

    return None

def read_pidfile(filename):

    if os.path.exists(filename):

        try:

            with open(filename) as f:

                content = f.read()

            return int(content.strip())

        except (ValueError, IOError):

            return None

    else:

        return None

def _turn_sigterm_into_systemexit():

    """

    Attempts to turn a SIGTERM exception into a SystemExit exception.

    """

    try:

        import signal

    except ImportError:

        return

    def handle_term(signo, frame):

        raise SystemExit

    signal.signal(signal.SIGTERM, handle_term)

class Monitor(object):

    """

    A file monitor and server stopper.

    It is a simplified version of pyramid pserve.Monitor, with little changes:

    -   The constructor takes extra_files and atexit

    -   The process is stopped by auto-kill with signal SIGTERM

    """

    def __init__(self, poll_interval, extra_files=[], atexit=None):

        self.module_mtimes = {}

        self.keep_running = True

        self.poll_interval = poll_interval

        self.extra_files = extra_files

        self.atexit = atexit

    def _exit(self):

        if self.atexit:

            self.atexit()

        os.kill(os.getpid(), signal.SIGTERM)

    def periodic_reload(self):

        while True:

            if not self.check_reload():

                self._exit()

                break

            time.sleep(self.poll_interval)

    def check_reload(self):

        filenames = list(self.extra_files)

        for module in list(sys.modules.values()):

            try:

                filename = module.__file__

            except (AttributeError, ImportError):

                continue

            if filename is not None:

                filenames.append(filename)

        for filename in filenames:

            try:

                stat = os.stat(filename)

                if stat:

                    mtime = stat.st_mtime

                else:

                    mtime = 0

            except (OSError, IOError):

                continue

            if filename.endswith('.pyc') and os.path.exists(filename[:-1]):

                mtime = max(os.stat(filename[:-1]).st_mtime, mtime)

            if not filename in self.module_mtimes:

                self.module_mtimes[filename] = mtime

            elif self.module_mtimes[filename] < mtime:

                print('%s changed; reloading...' % filename)

                return False

        return True