# -*- coding: utf-8 -*-

# Copyright(C) 2010  Romain Bignon, Christophe Benz
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.


from __future__ import with_statement

import logging
from threading import Timer, Event, RLock


__all__ = ['Scheduler']


class IScheduler(object):
    def schedule(self, interval, function, *args):
        raise NotImplementedError()

    def repeat(self, interval, function, *args):
        raise NotImplementedError()

    def run(self):
        raise NotImplementedError()

    def want_stop(self):
        raise NotImplementedError()

class Scheduler(IScheduler):
    def __init__(self):
        self.mutex = RLock()
        self.stop_event = Event()
        self.count = 0
        self.queue = {}

    def schedule(self, interval, function, *args):
        if self.stop_event.isSet():
            return

        with self.mutex:
            self.count += 1
            logging.debug('function "%s" will be called in %s seconds' % (function.__name__, interval))
            timer = Timer(interval, self._callback, (self.count, function, args))
            self.queue[self.count] = timer
            timer.start()
            return self.count

    def _callback(self, count, function, args):
        with self.mutex:
            self.queue.pop(count)
        return function(*args)

    def repeat(self, interval, function, *args):
        return self._repeat(True, interval, function, *args)

    def _repeat(self, first, interval, function, *args):
        return self.schedule(0 if first else interval, self._repeated_cb, interval, function, args)

    def _wait_to_stop(self):
        self.want_stop()
        with self.mutex:
            for e in self.queue.itervalues():
                e.cancel()
                e.join()

    def run(self):
        try:
            while 1:
                self.stop_event.wait(0.1)
        except KeyboardInterrupt:
            self._wait_to_stop()
            raise
        else:
            self._wait_to_stop()
        return True

    def want_stop(self):
        self.stop_event.set()

    def _repeated_cb(self, interval, function, args):
        function(*args)
        self._repeat(False, interval, function, *args)