# Copyright (C) 2009, Tutorius.org
#
# 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; either version 2 of the License, or
# (at your option) any later version.
#
# 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

import gobject

from ..filters import EventFilter
from ..properties import TIntProperty

class TimerEvent(EventFilter):
    """
    TimerEvent is a special EventFilter that uses gobject
    timeouts to trigger a state change after a specified amount
    of time. It must be used inside a gobject main loop to work.
    """
    timeout = TIntProperty(15, 0)

    def __init__(self, timeout=None):
        """Constructor.

        @param timeout timeout in seconds
        """
        super(TimerEvent,self).__init__()
        if timeout:
            self.timeout = timeout
        self._handler_id = None

    def install_handlers(self, callback, **kwargs):
        """install_handlers creates the timer and starts it"""
        super(TimerEvent,self).install_handlers(callback, **kwargs)
        #Create the timer
        self._handler_id = gobject.timeout_add_seconds(self.timeout, self._timeout_cb)

    def remove_handlers(self):
        """remove handler removes the timer"""
        super(TimerEvent,self).remove_handlers()
        if self._handler_id:
            try:
                #XXX What happens if this was already triggered?
                #remove the timer
                gobject.source_remove(self._handler_id)
            except:
                pass

    def _timeout_cb(self):
        """
        _timeout_cb triggers the eventfilter callback.

        It is necessary because gobject timers only stop if the callback they
        trigger returns False
        """
        self.do_callback()
        return False #Stops timeout

__event__ = {
    "name" : "TimerEvent",
    "display_name" : "Timed transition",
    "icon" : "clock",
    "class" : TimerEvent,
    "mandatory_props" : ["timeout"]
}