# 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 logging

from autotest_lib.server.cros import vboot_constants as vboot
from autotest_lib.server.cros.faft.firmware_test import FirmwareTest


class firmware_RollbackKernel(FirmwareTest):
    """
    Servo based kernel rollback test.

    This test requires a USB disk plugged-in, which contains a Chrome OS test
    image (built by "build_image --test"). In normal mode, this test rollbacks
    kernel A and results kernel B boot. It then rollbacks kernel B and
    results recovery boot. In developer mode, the firmware ignores kernel
    rollback check so it remains unchanged.
    """
    version = 1

    def ensure_kernel_on_non_recovery(self, part):
        """Ensure the requested kernel part on normal/dev boot path.

        If not, it may be a test failure during step 2 or 3, try to recover to
        the requested kernel on normal/dev mode by recovering the whole OS
        and rebooting.

        @param part: The expected kernel partition number.
        """
        if not self.check_root_part_on_non_recovery(part):
            logging.info('Recover the disk OS by running chromeos-install...')
            self.faft_client.system.run_shell_command('chromeos-install --yes')
            self.switcher.mode_aware_reboot()

    def initialize(self, host, cmdline_args, dev_mode=False):
        super(firmware_RollbackKernel, self).initialize(host, cmdline_args)
        self.backup_kernel()
        self.backup_cgpt_attributes()
        self.switcher.setup_mode('dev' if dev_mode else 'normal')
        self.setup_usbkey(usbkey=True, host=False)
        self.setup_kernel('a')

    def cleanup(self):
        self.ensure_kernel_on_non_recovery('a')
        self.restore_cgpt_attributes()
        self.restore_kernel()
        super(firmware_RollbackKernel, self).cleanup()

    def run_once(self, dev_mode=False):
        # Historical reason that the old models use a different value.
        if self.faft_client.system.get_platform_name() in (
                'Mario', 'Alex', 'ZGB'):
            recovery_reason = vboot.RECOVERY_REASON['RW_NO_OS']
        else:
            recovery_reason = (vboot.RECOVERY_REASON['DEP_RW_NO_DISK'],
                               vboot.RECOVERY_REASON['RW_NO_KERNEL'])

        if dev_mode:
            logging.info("Rollbacks kernel A.")
            self.check_state((self.check_root_part_on_non_recovery, 'a'))
            self.faft_client.kernel.move_version_backward('a')
            self.switcher.mode_aware_reboot()

            logging.info("Still kernel A boot since dev_mode ignores "
                         "kernel rollback check.")
            self.check_state((self.check_root_part_on_non_recovery, 'a'))
            self.faft_client.kernel.move_version_forward('a')
        else:
            logging.info("Rollbacks kernel A.")
            self.check_state((self.check_root_part_on_non_recovery, 'a'))
            self.faft_client.kernel.move_version_backward('a')
            self.switcher.mode_aware_reboot()

            logging.info("Expected kernel B boot and rollbacks kernel B.")
            self.check_state((self.check_root_part_on_non_recovery, 'b'))
            self.faft_client.kernel.move_version_backward('b')
            self.switcher.mode_aware_reboot()

            logging.info("Expected recovery boot and restores the OS image.")
            self.check_state((self.checkers.crossystem_checker, {
                                  'mainfw_type': 'recovery',
                                  'recovery_reason': recovery_reason,
                                  }))
            self.faft_client.kernel.move_version_forward(('a', 'b'))
            self.switcher.mode_aware_reboot()

            logging.info("Expected kernel A boot and done.")
            self.check_state((self.check_root_part_on_non_recovery, 'a'))