# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import dbus, logging, os, random, time

from autotest_lib.client.bin import test, utils
from autotest_lib.client.common_lib import error
from autotest_lib.client.cros import backchannel

from autotest_lib.client.cros import flimflam_test_path
import flimflam
import mm


class ResetAuthorizedContext(object):
    def __init__(self, test):
        self.test = test

    def __enter__(self):
        pass

    def __exit__(self, exception, value, traceback):
        if exception:
            self.test.SetAuthorized(1)
        return False


class network_3GRebootStress(test.test):
    version = 1

    def CountModems(self):
        count = len(mm.EnumerateDevices(''))
        logging.debug('Modem count is %d' % count)
        return count

    def EnsureModemAbsent(self):
        utils.poll_for_condition(
            lambda: self.CountModems() == 0,
            error.TestFail('Modem failed to disappear'))

    def EnsureModemPresent(self):
        utils.poll_for_condition(
            lambda: self.CountModems() == 1,
            error.TestFail('Modem failed to reappear'))

    def FindUsbDevicePath(self, modem_manager, modem_path):
        logging.info('Modem path: %s' % modem_path)

        props = modem_manager.Properties(modem_path)
        net_device = props['Device']
        logging.info('Network device: %s' % net_device)

        usb_interface_path = os.path.realpath('/sys/class/net/%s/device'
                                              % net_device)
        self.usb_device_path, _ = usb_interface_path.rsplit('/', 1)
        logging.info('USB device path: %s' % self.usb_device_path)

    def SetAuthorized(self, authorized):
        logging.debug('Setting authorized to %d' % authorized)
        authorized_path = '%s/authorized' % self.usb_device_path
        authorized_file = open(authorized_path, 'w')
        authorized_file.write('%d' % authorized)
        authorized_file.close()

    def ShouldContinue(self):
        should_continue = True
        message = 'Starting loop %d' % (self.loops_done + 1)

        if self.max_loops != None:
            if self.loops_done >= self.max_loops:
                return False
            loops_left = self.max_loops - self.loops_done
            message += '; %d loops left' % loops_left

        if self.max_seconds != None:
            seconds_done = time.time() - self.start_time
            if seconds_done >= self.max_seconds:
                return False
            seconds_left = self.max_seconds - seconds_done
            message += '; %d seconds left' % seconds_left

        message += '.'
        logging.info(message)

        return True


    # It takes a Gobi about 1.5 seconds to cycle away and back, on average.
    # Assume 2, to have a margin of error.  (If we run out of time, it's
    # fine, but we'd like to run the same number of loops every time.)
    def run_once(self, max_loops=300, max_seconds=600):
        # Use a backchannel so that flimflam will restart when the
        # test is over.  This ensures flimflam is in a known good
        # state even if this test fails.
        with backchannel.Backchannel():
            self.flim = flimflam.FlimFlam()

            # Enabling flimflam debugging makes it easier to debug
            # problems.  Tags will be cleared when the Backchannel
            # context exits and flimflam is restarted.
            self.flim.SetDebugTags('service+device+modem+portal+network')

            modem_manager, modem_path = mm.PickOneModem('')
            self.FindUsbDevicePath(modem_manager, modem_path)

            self.max_loops = max_loops
            self.max_seconds = max_seconds

            self.loops_done = 0
            self.start_time = time.time()

            # Use a context to ensure that we don't leave the modem
            # unauthorized if we die with an exception.
            with ResetAuthorizedContext(self):
                while self.ShouldContinue():
                    self.SetAuthorized(0)
                    self.EnsureModemAbsent()
                    self.SetAuthorized(1)
                    self.EnsureModemPresent()
                    self.loops_done += 1

            if self.loops_done < self.max_loops:
                logging.warning('Only got %d loops done in %d seconds. :(' %
                                (self.loops_done, max_seconds))