# Copyright 2016 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 json
import logging
import os

import common
from autotest_lib.client.common_lib import hosts
from autotest_lib.server import afe_utils
from autotest_lib.server.hosts import label_verify
from autotest_lib.server.hosts import repair


class ACPowerVerifier(hosts.Verifier):
    """Check for AC power and a reasonable battery charge."""

    def verify(self, host):
        # Temporarily work around a problem caused by some old FSI
        # builds that don't have the power_supply_info command by
        # ignoring failures.  The repair triggers believe that this
        # verifier can't be fixed by re-installing, which means if a DUT
        # gets stuck with one of those old builds, it can't be repaired.
        #
        # TODO(jrbarnette): This is for crbug.com/599158; we need a
        # better solution.
        try:
            info = host.get_power_supply_info()
        except:
            logging.exception('get_power_supply_info() failed')
            return
        try:
            if info['Line Power']['online'] != 'yes':
                raise hosts.AutoservVerifyError(
                        'AC power is not plugged in')
        except KeyError:
            logging.info('Cannot determine AC power status - '
                         'skipping check.')
        try:
            if float(info['Battery']['percentage']) < 50.0:
                raise hosts.AutoservVerifyError(
                        'Battery is less than 50%')
        except KeyError:
            logging.info('Cannot determine battery status - '
                         'skipping check.')


    @property
    def description(self):
        return 'The DUT is plugged in to AC power'


class WritableVerifier(hosts.Verifier):
    """
    Confirm the stateful file systems are writable.

    The standard linux response to certain unexpected file system errors
    (including hardware errors in block devices) is to change the file
    system status to read-only.  This checks that that hasn't happened.

    The test covers the two file systems that need to be writable for
    critical operations like AU:
      * The (unencrypted) stateful system which includes
        /mnt/stateful_partition.
      * The encrypted stateful partition, which includes /var.

    The test doesn't check various bind mounts; those are expected to
    fail the same way as their underlying main mounts.  Whether the
    Linux kernel can guarantee that is untested...
    """

    # N.B. Order matters here:  Encrypted stateful is loop-mounted from
    # a file in unencrypted stateful, so we don't test for errors in
    # encrypted stateful if unencrypted fails.
    _TEST_DIRECTORIES = ['/mnt/stateful_partition', '/var/tmp']

    def verify(self, host):
        # This deliberately stops looking after the first error.
        # See above for the details.
        for testdir in self._TEST_DIRECTORIES:
            filename = os.path.join(testdir, 'writable_test')
            command = 'touch %s && rm %s' % (filename, filename)
            rv = host.run(command=command, ignore_status=True)
            if rv.exit_status != 0:
                msg = 'Can\'t create a file in %s' % testdir
                raise hosts.AutoservVerifyError(msg)


    @property
    def description(self):
        return 'The stateful filesystems are writable'


class UpdateSuccessVerifier(hosts.Verifier):
    """
    Checks that the DUT has not failed its last provision job.

    At the start of update (e.g. for a Provision job), the code touches
    the file named in `host.PROVISION_FAILED`.  The file is located
    in a part of the stateful partition that will be removed when the
    update finishes.  Thus, the presence of the file indicates that a
    prior update failed.

    @return: True if there exists file /var/tmp/provision_failed, which
             indicates the last provision job failed.
             False if the file does not exist or the dut can't be reached.
    """
    def verify(self, host):
        result = host.run('test -f %s' % host.PROVISION_FAILED,
                          ignore_status=True)
        if result.exit_status == 0:
            raise hosts.AutoservVerifyError(
                    'Last AU on this DUT failed')


    @property
    def description(self):
        return 'The most recent AU attempt on this DUT succeeded'


class TPMStatusVerifier(hosts.Verifier):
    """Verify that the host's TPM is in a good state."""

    def verify(self, host):
        # This cryptohome command emits status information in JSON format. It
        # looks something like this:
        # {
        #    "installattrs": {
        #       ...
        #    },
        #    "mounts": [ {
        #       ...
        #    } ],
        #    "tpm": {
        #       "being_owned": false,
        #       "can_connect": true,
        #       "can_decrypt": false,
        #       "can_encrypt": false,
        #       "can_load_srk": true,
        #       "can_load_srk_pubkey": true,
        #       "enabled": true,
        #       "has_context": true,
        #       "has_cryptohome_key": false,
        #       "has_key_handle": false,
        #       "last_error": 0,
        #       "owned": true
        #    }
        # }
        output = host.run('cryptohome --action=status').stdout.strip()
        try:
            status = json.loads(output)
        except ValueError:
            logging.info('Cannot determine the Crytohome valid status - '
                         'skipping check.')
            return
        try:
            tpm = status['tpm']
            if not tpm['enabled']:
                raise hosts.AutoservVerifyError(
                        'TPM is not enabled -- Hardware is not working.')
            if not tpm['can_connect']:
                raise hosts.AutoservVerifyError(
                        ('TPM connect failed -- '
                         'last_error=%d.' % tpm['last_error']))
            if (tpm['owned'] and not tpm['can_load_srk']):
                raise hosts.AutoservVerifyError(
                        'Cannot load the TPM SRK')
            if (tpm['can_load_srk'] and not tpm['can_load_srk_pubkey']):
                raise hosts.AutoservVerifyError(
                        'Cannot load the TPM SRK public key')
        except KeyError:
            logging.info('Cannot determine the Crytohome valid status - '
                         'skipping check.')


    @property
    def description(self):
        return 'The host\'s TPM is available and working'


class PythonVerifier(hosts.Verifier):
    """Confirm the presence of a working Python interpreter."""

    def verify(self, host):
        result = host.run('python -c "import cPickle"',
                          ignore_status=True)
        if result.exit_status != 0:
            message = 'The python interpreter is broken'
            if result.exit_status == 127:
                search = host.run('which python', ignore_status=True)
                if search.exit_status != 0 or not search.stdout:
                    message = ('Python is missing; may be caused by '
                               'powerwash')
            raise hosts.AutoservVerifyError(message)


    @property
    def description(self):
        return 'Python on the host is installed and working'


class ServoResetRepair(hosts.RepairAction):
    """Repair a Chrome device by resetting it with servo."""

    def repair(self, host):
        if not host.servo:
            raise hosts.AutoservRepairError(
                    '%s has no servo support.' % host.hostname)
        host.servo.get_power_state_controller().reset()
        if host.wait_up(host.BOOT_TIMEOUT):
            return
        raise hosts.AutoservRepairError(
                '%s is still offline after reset.' % host.hostname)


    @property
    def description(self):
        return 'Reset the DUT via servo'


class FirmwareRepair(hosts.RepairAction):
    """
    Reinstall the firmware image using servo.

    This repair function attempts to use servo to install the DUT's
    designated "stable firmware version".

    This repair method only applies to DUTs used for FAFT.
    """

    def repair(self, host):
        if not host._is_firmware_repair_supported():
            raise hosts.AutoservRepairError(
                    'Firmware repair is not applicable to host %s.' %
                    host.hostname)
        if not host.servo:
            raise hosts.AutoservRepairError(
                    '%s has no servo support.' % host.hostname)
        host.firmware_install()


    @property
    def description(self):
        return 'Re-install the stable firmware'


class AutoUpdateRepair(hosts.RepairAction):
    """
    Repair by re-installing a test image using autoupdate.

    Try to install the DUT's designated "stable test image" using the
    standard procedure for installing a new test image via autoupdate.
    """

    def repair(self, host):
        afe_utils.machine_install_and_update_labels(host, repair=True)


    @property
    def description(self):
        return 'Re-install the stable build via AU'


class PowerWashRepair(AutoUpdateRepair):
    """
    Powerwash the DUT, then re-install using autoupdate.

    Powerwash the DUT, then attempt to re-install a stable test image as
    for `AutoUpdateRepair`.
    """

    def repair(self, host):
        host.run('echo "fast safe" > '
                 '/mnt/stateful_partition/factory_install_reset')
        host.reboot(timeout=host.POWERWASH_BOOT_TIMEOUT, wait=True)
        super(PowerWashRepair, self).repair(host)


    @property
    def description(self):
        return 'Powerwash and then re-install the stable build via AU'


class ServoInstallRepair(hosts.RepairAction):
    """
    Reinstall a test image from USB using servo.

    Use servo to re-install the DUT's designated "stable test image"
    from servo-attached USB storage.
    """

    def repair(self, host):
        if not host.servo:
            raise hosts.AutoservRepairError(
                    '%s has no servo support.' % host.hostname)
        host.servo_install(host.stage_image_for_servo())


    @property
    def description(self):
        return 'Reinstall from USB using servo'


def create_cros_repair_strategy():
    """Return a `RepairStrategy` for a `CrosHost`."""
    verify_dag = [
        (repair.SshVerifier,         'ssh',      []),
        (ACPowerVerifier,            'power',    ['ssh']),
        (WritableVerifier,           'writable', ['ssh']),
        (TPMStatusVerifier,          'tpm',      ['ssh']),
        (UpdateSuccessVerifier,      'good_au',  ['ssh']),
        (PythonVerifier,             'python',   ['ssh']),
        (repair.LegacyHostVerifier,  'cros',     ['ssh']),
        (label_verify.LabelVerifier, 'label',    ['ssh']),
    ]

    # The dependencies and triggers for the 'au', 'powerwash', and 'usb'
    # repair actions stack up:  Each one is able to repair progressively
    # more verifiers than the one before.  The 'triggers' lists below
    # show the progression.
    #
    # N.B. AC power detection depends on software on the DUT, and there
    # have been bugs where detection failed even though the DUT really
    # did have power.  So, we make the 'power' verifier a trigger for
    # reinstall repair actions, too.
    #
    # TODO(jrbarnette):  AU repair can't fix all problems reported by
    # the 'cros' verifier; it's listed as an AU trigger as a
    # simplification.  The ultimate fix is to split the 'cros' verifier
    # into smaller individual verifiers.

    usb_triggers       = ['ssh', 'writable']
    powerwash_triggers = ['tpm', 'good_au']
    au_triggers        = ['python', 'cros', 'power']

    repair_actions = [
        # RPM cycling must precede Servo reset:  if the DUT has a dead
        # battery, we need to reattach AC power before we reset via servo.
        (repair.RPMCycleRepair, 'rpm', [], ['ssh', 'power']),
        (ServoResetRepair, 'reset', [], ['ssh']),

        # TODO(jrbarnette):  the real dependency for firmware isn't
        # 'cros', but rather a to-be-created verifier that replaces
        # CrosHost.verify_firmware_status()
        #
        # N.B. FirmwareRepair can't fix a 'good_au' failure directly,
        # because it doesn't remove the flag file that triggers the
        # failure.  We include it as a repair trigger because it's
        # possible the the last update failed because of the firmware,
        # and we want the repair steps below to be able to trust the
        # firmware.
        (FirmwareRepair, 'firmware', [], ['ssh', 'cros', 'good_au']),

        (repair.RebootRepair, 'reboot', ['ssh'], ['writable']),

        (AutoUpdateRepair, 'au',
                usb_triggers + powerwash_triggers, au_triggers),
        (PowerWashRepair, 'powerwash',
                usb_triggers, powerwash_triggers + au_triggers),
        (ServoInstallRepair, 'usb',
                [], usb_triggers + powerwash_triggers + au_triggers),
    ]
    return hosts.RepairStrategy(verify_dag, repair_actions)


def create_moblab_repair_strategy():
    """
    Return a `RepairStrategy` for a `MoblabHost`.

    Moblab is a subset of the CrOS verify and repair.  Several pieces
    are removed because they're not expected to be meaningful.  Some
    others are removed for more specific reasons:

    'tpm':  Moblab DUTs don't run the tests that matter to this
        verifier.  TODO(jrbarnette)  This assertion is unproven.

    'good_au':  This verifier can't pass, because the Moblab AU
        procedure doesn't properly delete CrosHost.PROVISION_FAILED.
        TODO(jrbarnette) We should refactor _machine_install() so that
        it can be different for Moblab.

    'firmware':  Moblab DUTs shouldn't be in FAFT pools, so we don't try
        this.

    'powerwash':  Powerwash on Moblab causes trouble with deleting the
        DHCP leases file, so we skip it.
    """
    verify_dag = [
        (repair.SshVerifier,         'ssh',     []),
        (ACPowerVerifier,            'power',   ['ssh']),
        (PythonVerifier,             'python',  ['ssh']),
        (repair.LegacyHostVerifier,  'cros',    ['ssh']),
    ]
    repair_actions = [
        (repair.RPMCycleRepair, 'rpm', [], ['ssh', 'power']),
        (AutoUpdateRepair, 'au', ['ssh'], ['python', 'cros', 'power']),
    ]
    return hosts.RepairStrategy(verify_dag, repair_actions)