#!/usr/bin/python3

# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 3 of the License, or (at your option) any
# later version.  See http://www.gnu.org/copyleft/lgpl.html for the full text
# of the license.

__author__ = 'Bastien Nocera'
__email__ = 'hadess@hadess.net'
__copyright__ = '(c) 2019 Red Hat Inc.'
__license__ = 'LGPL 3+'

import unittest
import sys
import subprocess
import fcntl
import os
import time

import taptestrunner

try:
    # Do all non-standard imports here so we can skip the tests if any
    # needed packages are not available.
    import dbus
    import dbus.mainloop.glib
    import dbusmock
    from gi.repository import GLib
    from gi.repository import Gio

    dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)

    class TestLowMemoryMonitor(dbusmock.DBusTestCase):
        '''Test GMemoryMonitorDBus'''

        @classmethod
        def setUpClass(klass):
            klass.start_system_bus()
            klass.dbus_con = klass.get_dbus(True)

        @unittest.skipIf('DEB_ALLOW_FLAKY_TESTS' not in os.environ,
                         'https://bugs.debian.org/995178')
        def setUp(self):
            try:
                Gio.MemoryMonitor
            except AttributeError:
                raise unittest.SkipTest('Low memory monitor not in '
                                        'introspection data. Requires '
                                        'GObject-Introspection ≥ 1.63.2')
            try:
                (self.p_mock, self.obj_lmm) = self.spawn_server_template(
                    'low_memory_monitor', {}, stdout=subprocess.PIPE)
            except ModuleNotFoundError:
                raise unittest.SkipTest("Low memory monitor dbusmock template not "
                                        "found. Requires dbusmock ≥ 0.18.4.")
            # set log to nonblocking
            flags = fcntl.fcntl(self.p_mock.stdout, fcntl.F_GETFL)
            fcntl.fcntl(self.p_mock.stdout, fcntl.F_SETFL, flags | os.O_NONBLOCK)
            self.last_warning = -1
            self.dbusmock = dbus.Interface(self.obj_lmm, dbusmock.MOCK_IFACE)
            self.memory_monitor = Gio.MemoryMonitor.dup_default()
            self.memory_monitor.connect("low-memory-warning", self.memory_warning_cb)
            self.mainloop = GLib.MainLoop()
            self.main_context = self.mainloop.get_context()

        def tearDown(self):
            self.p_mock.terminate()
            self.p_mock.wait()

        def assertEventually(self, condition, message=None, timeout=50):
            '''Assert that condition function eventually returns True.

            Timeout is in deciseconds, defaulting to 50 (5 seconds). message is
            printed on failure.
            '''
            print('Waiting up to {}/10 seconds for {!r} to be true'.format(timeout, condition))
            orig_timeout = timeout

            while timeout >= 0:
                print('Loop iteration')
                context = GLib.MainContext.default()
                while context.iteration(False):
                    print('Iterating main loop')
                    pass
                if condition():
                    print('Condition reached')
                    break
                timeout -= 1
                time.sleep(0.1)
            else:
                print('Condition not reached in {}/10 seconds'.format(orig_timeout))
                self.fail(message or 'timed out waiting for ' + str(condition))

        def memory_warning_cb(self, monitor, level):
            print('low-memory-warning: monitor {!r} reports level {}'.format(
                monitor,
                level,
            ))
            self.last_warning = level
            self.main_context.wakeup()

        def test_low_memory_warning_signal(self):
            '''LowMemoryWarning signal'''

            # Wait 2 seconds
            timeout = 2
            while timeout > 0:
                print('Waiting 0.5s for stray events...')
                time.sleep(0.5)
                timeout -= 0.5
                self.main_context.iteration(False)

            print('Emitting mock low-memory warning, level 100: try to free memory')
            self.dbusmock.EmitWarning(100)
            # Wait 2 seconds or until warning
            self.assertEventually(lambda: self.last_warning == 100, "'100' low-memory warning not received", 100)

            print('Emitting mock low-memory warning, level 255: OOM imminent')
            self.dbusmock.EmitWarning(255)
            # Wait 2 seconds or until warning
            self.assertEventually(lambda: self.last_warning == 255, "'255' low-memory warning not received", 100)

except ImportError as e:
    @unittest.skip("Cannot import %s" % e.name)
    class TestLowMemoryMonitor(unittest.TestCase):
        def test_low_memory_warning_signal(self):
            pass

if __name__ == '__main__':
    unittest.main(testRunner=taptestrunner.TAPTestRunner())