# Copyright 2018 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 logging
import os

from autotest_lib.client.bin import utils
from autotest_lib.client.common_lib import error
from autotest_lib.client.cros.update_engine import nano_omaha_devserver
from autotest_lib.client.cros.update_engine import update_engine_test

class autoupdate_Backoff(update_engine_test.UpdateEngineTest):
    """
    Tests update_engine's backoff mechanism.

    When an update fails, update_engine will not allow another update to the
    same URL for a certain backoff period. The backoff period is stored in
    /var/lib/update_engine/prefs/backoff-expiry-time. It is stored as an
    integer representing the number of microseconds since 1/1/1601.

    By default, backoff is disabled on test images but by creating a
    'no-ignore-backoff' pref we can test it.

    """
    version = 1

    _BACKOFF_DISABLED = 'Resetting backoff expiry time as payload backoff is ' \
                        'disabled'
    _BACKOFF_ENABLED = 'Incrementing the backoff expiry time'
    _BACKOFF_ERROR = 'Updating payload state for error code: 40 (' \
                     'ErrorCode::kOmahaUpdateDeferredForBackoff)'
    _BACKOFF_EXPIRY_TIME_PREF = 'backoff-expiry-time'
    _NO_IGNORE_BACKOFF_PREF = 'no-ignore-backoff'


    def cleanup(self):
        utils.run('rm %s' % self._no_ignore_backoff, ignore_status=True)
        utils.run('rm %s' % self._backoff_expiry_time, ignore_status=True)
        super(autoupdate_Backoff, self).cleanup()


    def run_once(self, image_url, image_size, sha256, backoff):
        self._no_ignore_backoff = os.path.join(
            self._UPDATE_ENGINE_PREFS_DIR, self._NO_IGNORE_BACKOFF_PREF)
        self._backoff_expiry_time = os.path.join(
            self._UPDATE_ENGINE_PREFS_DIR, self._BACKOFF_EXPIRY_TIME_PREF)
        utils.run('touch %s' % self._no_ignore_backoff, ignore_status=True)

        # Only set one URL in the omaha response so we can test the backoff
        # functionality quicker.
        self._omaha = nano_omaha_devserver.NanoOmahaDevserver(
            backoff=backoff, num_urls=1)
        self._omaha.set_image_params(image_url, image_size, sha256)
        self._omaha.start()

        # Start the update.
        self._check_for_update(port=self._omaha.get_port(), interactive=False)
        self._wait_for_progress(0.2)

        # Disable internet so the update fails.
        self._disable_internet()
        self._wait_for_update_to_fail()
        self._enable_internet()

        if backoff:
            self._check_update_engine_log_for_entry(self._BACKOFF_ENABLED,
                                                    raise_error=True)
            utils.run('cat %s' % self._backoff_expiry_time)
            try:
                self._check_for_update(port=self._omaha.get_port(),
                                       interactive=False,
                                       wait_for_completion=True)
            except error.CmdError as e:
                logging.info('Update failed as expected.')
                logging.error(e)
                self._check_update_engine_log_for_entry(self._BACKOFF_ERROR,
                                                        raise_error=True)
                return

            raise error.TestFail('Second update attempt succeeded. It was '
                                 'supposed to have failed due to backoff.')
        else:
            self._check_update_engine_log_for_entry(self._BACKOFF_DISABLED,
                                                    raise_error=True)
            self._check_for_update(port=self._omaha.get_port(),
                                   interactive=False)
            self._wait_for_update_to_complete()