# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
This module provides support for Twisted to interact with the gtk3 mainloop
via Gobject introspection. This is like gi, but slightly slower and requires a
working $DISPLAY.

In order to use this support, simply do the following::

from twisted.internet import gtk3reactor
gtk3reactor.install()

If you wish to use a GApplication, register it with the reactor::

from twisted.internet import reactor
reactor.registerGApplication(app)

Then use twisted.internet APIs as usual.
"""

from __future__ import division, absolute_import

import os

from twisted.internet import gireactor
from twisted.python import runtime

# Newer versions of gtk3/pygoject raise a RuntimeError, or just break in a
# confusing manner, if the program is not running under X11. We therefore try
# to fail in a more reasonable manner, and check for $DISPLAY as a reasonable
# approximation of availability of X11. This is somewhat over-aggressive,
# since some older versions of gtk3/pygobject do work with missing $DISPLAY,
# but it's too hard to figure out which, so we always require it.
if (runtime.platform.getType() == 'posix' and
not runtime.platform.isMacOSX() and not os.environ.get("DISPLAY")):
raise ImportError(
"Gtk3 requires X11, and no DISPLAY environment variable is set")


class Gtk3Reactor(gireactor.GIReactor):
"""
A reactor using the gtk3+ event loop.
"""

def __init__(self):
"""
Override init to set the C{useGtk} flag.
"""
gireactor.GIReactor.__init__(self, useGtk=True)



class PortableGtk3Reactor(gireactor.PortableGIReactor):
"""
Portable GTK+ 3.x reactor.
"""
def __init__(self):
"""
Override init to set the C{useGtk} flag.
"""
gireactor.PortableGIReactor.__init__(self, useGtk=True)



def install():
"""
Configure the Twisted mainloop to be run inside the gtk3+ mainloop.
"""
if runtime.platform.getType() == 'posix':
reactor = Gtk3Reactor()
else:
reactor = PortableGtk3Reactor()

from twisted.internet.main import installReactor
installReactor(reactor)
return reactor


__all__ = ['install']