# Copyright (c) 2013 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
import logging
import time

from autotest_lib.client.cros.networking import shill_proxy


class CellularProxy(shill_proxy.ShillProxy):
    """Wrapper around shill dbus interface used by cellular tests."""

    # Properties exposed by shill.
    DEVICE_PROPERTY_DBUS_OBJECT = 'DBus.Object'
    DEVICE_PROPERTY_ICCID = 'Cellular.ICCID'
    DEVICE_PROPERTY_SIM_LOCK_STATUS = 'Cellular.SIMLockStatus'

    # Keys into the dictionaries exposed as properties.
    PROPERTY_KEY_SIM_LOCK_TYPE = 'LockType'
    PROPERTY_KEY_SIM_LOCK_ENABLED = 'LockEnabled'
    PROPERTY_KEY_SIM_LOCK_RETRIES_LEFT = 'RetriesLeft'

    # Valid values taken by properties exposed by shill.
    VALUE_SIM_LOCK_TYPE_PIN = 'sim-pin'
    VALUE_SIM_LOCK_TYPE_PUK = 'sim-puk'

    # DBus errors raised by shill.
    ERROR_INCORRECT_PIN = 'org.chromium.flimflam.Error.IncorrectPin'
    ERROR_PIN_BLOCKED = 'org.chromium.flimflam.Error.PinBlocked'

    def set_logging_for_cellular_test(self):
        """Set the logging in shill for a test of cellular technology.

        Set the log level to |ShillProxy.LOG_LEVEL_FOR_TEST| and the log scopes
        to the ones defined in |ShillProxy.LOG_SCOPES_FOR_TEST| for
        |ShillProxy.TECHNOLOGY_CELLULAR|.

        """
        self.set_logging_for_test(self.TECHNOLOGY_CELLULAR)


    def find_cellular_service_object(self):
        """Returns the first dbus object found that is a cellular service.

        @return DBus object for the first cellular service found. None if no
                service found.

        """
        return self.find_object('Service', {'Type': self.TECHNOLOGY_CELLULAR})


    def find_cellular_device_object(self):
        """Returns the first dbus object found that is a cellular device.

        @return DBus object for the first cellular device found. None if no
                device found.

        """
        return self.find_object('Device', {'Type': self.TECHNOLOGY_CELLULAR})


    def reset_modem(self, modem, expect_device=True, expect_powered=True,
                    expect_service=True):
        """Reset |modem|.

        Do, in sequence,
        (1) Ensure that the current device object disappears.
        (2) If |expect_device|, ensure that the device reappears.
        (3) If |expect_powered|, ensure that the device is powered.
        (4) If |expect_service|, ensure that the service reappears.

        This function does not check the service state for the device after
        reset.

        @param modem: DBus object for the modem to reset.
        @param expect_device: If True, ensure that a DBus object reappears for
                the same modem after the reset.
        @param expect_powered: If True, ensure that the modem is powered on
                after the reset.
        @param expect_service: If True, ensure that a service managing the
                reappeared modem also reappears.

        @return (device, service)
                device: DBus object for the reappeared Device after the reset.
                service: DBus object for the reappeared Service after the reset.
                Either of these may be None, if the object is not expected to
                reappear.

        @raises ShillProxyError if any of the conditions (1)-(4) fail.

        """
        logging.info('Resetting modem')
        # Obtain identifying information about the modem.
        # ICCID is the only property we are guaranteed to obtain whenever the
        # device is present. Others, like imei/imsi are not present if the
        # device is locked.
        properties = modem.GetProperties(utf8_strings=True)
        iccid = properties.get(self.DEVICE_PROPERTY_ICCID)
        if not iccid:
            raise shill_proxy.ShillProxyError(
                    'Failed to get identifying information for the modem.')
        old_modem_path = modem.object_path
        old_modem_mm_object = properties.get(self.DEVICE_PROPERTY_DBUS_OBJECT)
        if not old_modem_mm_object:
            raise shill_proxy.ShillProxyError(
                    'Failed to get the mm object path for the modem.')

        modem.Reset()

        # (1) Wait for the old modem to disappear
        CellularProxy._poll_for_condition(
                lambda: self._is_old_modem_gone(old_modem_path,
                                                old_modem_mm_object),
                'Old modem disappeared')

        # (2) Wait for the device to reappear
        if not expect_device:
            return None, None
        # The timeout here should be sufficient for our slowest modem to
        # reappear.
        CellularProxy._poll_for_condition(
                lambda: self._get_reappeared_modem(iccid, old_modem_mm_object),
                desc='The modem reappeared after reset.',
                timeout=60)
        new_modem = self._get_reappeared_modem(iccid, old_modem_mm_object)

        # (3) Check powered state of the device
        if not expect_powered:
            return new_modem, None
        self.wait_for_property_in(new_modem, self.DEVICE_PROPERTY_POWERED,
                                  [self.VALUE_POWERED_ON], timeout_seconds=10)

        # (4) Check that service reappears
        if not expect_service:
            return new_modem, None
        new_service = self.get_service_for_device(new_modem)
        if not new_service:
            raise shill_proxy.ShillProxyError(
                    'Failed to find a shill service managing the reappeared '
                    'device.')
        return new_modem, new_service


    # TODO(pprabhu) Use utils.poll_for_condition instead
    SLEEP_INTERVAL = 0.1
    @staticmethod
    def _poll_for_condition(condition, desc, timeout=10):
        """Poll till |condition| is satisfied.

        @param condition: A function taking no arguments. The condition is
                met when the return value can be cast to the bool True.
        @param desc: The description given when we timeout waiting for
                |condition|.

        """
        start_time = time.time()
        while True:
            value = condition()
            if value:
                return value
            if(time.time() + CellularProxy.SLEEP_INTERVAL - start_time >
               timeout):
                raise shill_proxy.ShillProxyError(
                        'Timed out waiting for condition %s.' % desc)
            time.sleep(CellularProxy.SLEEP_INTERVAL)


    def _is_old_modem_gone(self, modem_path, modem_mm_object):
        """Tests if the DBus object for modem disappears after Reset.

        @param modem_path: The DBus path for the modem object that must vanish.
        @param modem_mm_object: The modemmanager object path reported by the
            old modem. This is unique everytime a new modem is (re)exposed.

        @return True if the object disappeared, false otherwise.

        """
        device = self.get_dbus_object(self.DBUS_TYPE_DEVICE, modem_path)
        try:
            properties = device.GetProperties()
            # DBus object exists, perhaps a reappeared device?
            return (properties.get(self.DEVICE_PROPERTY_DBUS_OBJECT) !=
                    modem_mm_object)
        except dbus.DBusException as e:
            if e.get_dbus_name() == self.DBUS_ERROR_UNKNOWN_OBJECT:
                return True
            return False


    def _get_reappeared_modem(self, iccid, old_modem_mm_object):
        """Check that a vanished modem reappers.

        @param iccid: The unique constant ICCID reported by the vanished modem.
        @param old_modem_mm_object: The previously reported modemmanager object
                path for this modem.

        @return The reappeared DBus object, if any. None otherwise.

        """
        # TODO(pprabhu) This will break if we have multiple cellular devices
        # in the system at the same time.
        device = self.find_cellular_device_object()
        if not device:
            return None
        properties = device.GetProperties(utf8_strings=True)
        if (iccid == properties.get(self.DEVICE_PROPERTY_ICCID) and
            (old_modem_mm_object !=
             properties.get(self.DEVICE_PROPERTY_DBUS_OBJECT))):
            return device
        return None