# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

import base64
import ConfigParser
import json
import os
import socket
import StringIO
import traceback
import warnings

from contextlib import contextmanager

from application_cache import ApplicationCache
from decorators import do_crash_check
from keys import Keys
from marionette_transport import MarionetteTransport

from mozrunner import B2GEmulatorRunner

import geckoinstance
import errors

class HTMLElement(object):
    """
    Represents a DOM Element.
    """

    CLASS = "class name"
    SELECTOR = "css selector"
    ID = "id"
    NAME = "name"
    LINK_TEXT = "link text"
    PARTIAL_LINK_TEXT = "partial link text"
    TAG = "tag name"
    XPATH = "xpath"

    def __init__(self, marionette, id):
        self.marionette = marionette
        assert(id is not None)
        self.id = id

    def __str__(self):
        return self.id

    def __eq__(self, other_element):
        return self.id == other_element.id

    def find_element(self, method, target):
        '''
        Returns an HTMLElement instance that matches the specified method and target, relative to the current element.

        For more details on this function, see the find_element method in the
        Marionette class.
        '''
        return self.marionette.find_element(method, target, self.id)

    def find_elements(self, method, target):
        '''
        Returns a list of all HTMLElement instances that match the specified method and target in the current context.

        For more details on this function, see the find_elements method in the
        Marionette class.
        '''
        return self.marionette.find_elements(method, target, self.id)

    def get_attribute(self, attribute):
        '''
        Returns the requested attribute (or None, if no attribute is set).

        :param attribute: The name of the attribute.
        '''
        return self.marionette._send_message('getElementAttribute', 'value', id=self.id, name=attribute)

    def click(self):
        return self.marionette._send_message('clickElement', 'ok', id=self.id)

    def tap(self, x=None, y=None):
        '''
        Simulates a set of tap events on the element.

        :param x: X-coordinate of tap event. If not given, default to the
         center of the element.
        :param y: Y-coordinate of tap event. If not given, default to the
         center of the element.
        '''
        return self.marionette._send_message('singleTap', 'ok', id=self.id, x=x, y=y)

    @property
    def text(self):
        '''
        Returns the visible text of the element, and its child elements.
        '''
        return self.marionette._send_message('getElementText', 'value', id=self.id)

    def send_keys(self, *string):
        '''
        Sends the string via synthesized keypresses to the element.
        '''
        typing = []
        for val in string:
            if isinstance(val, Keys):
                typing.append(val)
            elif isinstance(val, int):
                val = str(val)
                for i in range(len(val)):
                    typing.append(val[i])
            else:
                for i in range(len(val)):
                    typing.append(val[i])
        return self.marionette._send_message('sendKeysToElement', 'ok', id=self.id, value=typing)

    def clear(self):
        '''
        Clears the input of the element.
        '''
        return self.marionette._send_message('clearElement', 'ok', id=self.id)

    def is_selected(self):
        '''
        Returns True if the element is selected.
        '''
        return self.marionette._send_message('isElementSelected', 'value', id=self.id)

    def is_enabled(self):
        '''
        This command will return False if all the following criteria are met otherwise return True:

        * A form control is disabled.
        * A HtmlElement has a disabled boolean attribute.

        '''
        return self.marionette._send_message('isElementEnabled', 'value', id=self.id)

    def is_displayed(self):
        '''
        Returns True if the element is displayed.
        '''
        return self.marionette._send_message('isElementDisplayed', 'value', id=self.id)

    @property
    def size(self):
        '''
        A dictionary with the size of the element.
        '''
        warnings.warn("The size property has been deprecated and will be removed in a future version. \
            Please use HTMLElement#rect", DeprecationWarning)
        return self.marionette._send_message('getElementSize', 'value', id=self.id)

    @property
    def tag_name(self):
        '''
        The tag name of the element.
        '''
        return self.marionette._send_message('getElementTagName', 'value', id=self.id)

    @property
    def location(self):
        """Get an element's location on the page.

        The returned point will contain the x and y coordinates of the
        top left-hand corner of the given element.  The point (0,0)
        refers to the upper-left corner of the document.

        :returns: a dictionary containing x and y as entries

        """
        warnings.warn("The location property has been deprecated and will be removed in a future version. \
            Please use HTMLElement#rect", DeprecationWarning)
        return self.marionette._send_message("getElementLocation", "value", id=self.id)

    @property
    def rect(self):
        """
            this will return a dictionary with the following:

            * x and y represent the top left coordinates of the WebElement relative to top left corner of the document.
            * height and the width will contain the height and the width of the DOMRect of the WebElement.

        """

        return self.marionette._send_message("getElementRect", "value", id=self.id)

    def value_of_css_property(self, property_name):
        '''
        Gets the value of the specified CSS property name.

        :param property_name: Property name to get the value of.
        '''
        return self.marionette._send_message('getElementValueOfCssProperty', 'value',
                                             id=self.id,
                                             propertyName=property_name)
    def submit(self):
        '''
        Submits if the element is a form or is within a form
        '''
        return self.marionette._send_message('submitElement', 'ok', id=self.id)

class Actions(object):
    '''
    An Action object represents a set of actions that are executed in a particular order.

    All action methods (press, etc.) return the Actions object itself, to make
    it easy to create a chain of events.

    Example usage:

    ::

        # get html file
        testAction = marionette.absolute_url("testFool.html")
        # navigate to the file
        marionette.navigate(testAction)
        # find element1 and element2
        element1 = marionette.find_element("id", "element1")
        element2 = marionette.find_element("id", "element2")
        # create action object
        action = Actions(marionette)
        # add actions (press, wait, move, release) into the object
        action.press(element1).wait(5). move(element2).release()
        # fire all the added events
        action.perform()
    '''

    def __init__(self, marionette):
        self.action_chain = []
        self.marionette = marionette
        self.current_id = None

    def press(self, element, x=None, y=None):
        '''
        Sends a 'touchstart' event to this element.

        If no coordinates are given, it will be targeted at the center of the
        element. If given, it will be targeted at the (x,y) coordinates
        relative to the top-left corner of the element.

        :param element: The element to press on.
        :param x: Optional, x-coordinate to tap, relative to the top-left
         corner of the element.
        :param y: Optional, y-coordinate to tap, relative to the top-left
         corner of the element.
        '''
        element=element.id
        self.action_chain.append(['press', element, x, y])
        return self

    def release(self):
        '''
        Sends a 'touchend' event to this element.

        May only be called if press() has already be called on this element.

        If press and release are chained without a move action between them,
        then it will be processed as a 'tap' event, and will dispatch the
        expected mouse events ('mousemove' (if necessary), 'mousedown',
        'mouseup', 'mouseclick') after the touch events. If there is a wait
        period between press and release that will trigger a contextmenu,
        then the 'contextmenu' menu event will be fired instead of the
        touch/mouse events.
        '''
        self.action_chain.append(['release'])
        return self

    def move(self, element):
        '''
        Sends a 'touchmove' event at the center of the target element.

        :param element: Element to move towards.

        May only be called if press() has already be called.
        '''
        element=element.id
        self.action_chain.append(['move', element])
        return self

    def move_by_offset(self, x, y):
        '''
        Sends 'touchmove' event to the given x, y coordinates relative to the top-left of the currently touched element.

        May only be called if press() has already be called.

        :param x: Specifies x-coordinate of move event, relative to the
         top-left corner of the element.
        :param y: Specifies y-coordinate of move event, relative to the
         top-left corner of the element.
        '''
        self.action_chain.append(['moveByOffset', x, y])
        return self

    def wait(self, time=None):
        '''
        Waits for specified time period.

        :param time: Time in seconds to wait. If time is None then this has no effect for a single action chain. If used inside a multi-action chain, then time being None indicates that we should wait for all other currently executing actions that are part of the chain to complete.
        '''
        self.action_chain.append(['wait', time])
        return self

    def cancel(self):
        '''
        Sends 'touchcancel' event to the target of the original 'touchstart' event.

        May only be called if press() has already be called.
        '''
        self.action_chain.append(['cancel'])
        return self

    def tap(self, element, x=None, y=None):
        '''
        Performs a quick tap on the target element.

        :param element: The element to tap.
        :param x: Optional, x-coordinate of tap, relative to the top-left
         corner of the element. If not specified, default to center of
         element.
        :param y: Optional, y-coordinate of tap, relative to the top-left
         corner of the element. If not specified, default to center of
         element.

        This is equivalent to calling:

        ::

          action.press(element, x, y).release()
        '''
        element=element.id
        self.action_chain.append(['press', element, x, y])
        self.action_chain.append(['release'])
        return self

    def double_tap(self, element, x=None, y=None):
        '''
        Performs a double tap on the target element.

        :param element: The element to double tap.
        :param x: Optional, x-coordinate of double tap, relative to the
         top-left corner of the element.
        :param y: Optional, y-coordinate of double tap, relative to the
         top-left corner of the element.
        '''
        element=element.id
        self.action_chain.append(['press', element, x, y])
        self.action_chain.append(['release'])
        self.action_chain.append(['press', element, x, y])
        self.action_chain.append(['release'])
        return self

    def flick(self, element, x1, y1, x2, y2, duration=200):
        '''
        Performs a flick gesture on the target element.

        :param element: The element to perform the flick gesture on.
        :param x1: Starting x-coordinate of flick, relative to the top left
         corner of the element.
        :param y1: Starting y-coordinate of flick, relative to the top left
         corner of the element.
        :param x2: Ending x-coordinate of flick, relative to the top left
         corner of the element.
        :param y2: Ending y-coordinate of flick, relative to the top left
         corner of the element.
        :param duration: Time needed for the flick gesture for complete (in
         milliseconds).
        '''
        element = element.id
        elapsed = 0
        time_increment = 10
        if time_increment >= duration:
            time_increment = duration
        move_x = time_increment*1.0/duration * (x2 - x1)
        move_y = time_increment*1.0/duration * (y2 - y1)
        self.action_chain.append(['press', element, x1, y1])
        while elapsed < duration:
            elapsed += time_increment
            self.action_chain.append(['moveByOffset', move_x, move_y])
            self.action_chain.append(['wait', time_increment/1000])
        self.action_chain.append(['release'])
        return self

    def long_press(self, element, time_in_seconds, x=None, y=None):
        '''
        Performs a long press gesture on the target element.

        :param element: The element to press.
        :param time_in_seconds: Time in seconds to wait before releasing the press.
        :param x: Optional, x-coordinate to tap, relative to the top-left
         corner of the element.
        :param y: Optional, y-coordinate to tap, relative to the top-left
         corner of the element.

        This is equivalent to calling:

        ::

          action.press(element, x, y).wait(time_in_seconds).release()

        '''
        element = element.id
        self.action_chain.append(['press', element, x, y])
        self.action_chain.append(['wait', time_in_seconds])
        self.action_chain.append(['release'])
        return self

    def perform(self):
        '''
        Sends the action chain built so far to the server side for execution and clears the current chain of actions.
        '''
        self.current_id = self.marionette._send_message('actionChain', 'value', chain=self.action_chain, nextId=self.current_id)
        self.action_chain = []
        return self

class MultiActions(object):
    '''
    A MultiActions object represents a sequence of actions that may be
    performed at the same time. Its intent is to allow the simulation
    of multi-touch gestures.
    Usage example:

    ::

      # create multiaction object
      multitouch = MultiActions(marionette)
      # create several action objects
      action_1 = Actions(marionette)
      action_2 = Actions(marionette)
      # add actions to each action object/finger
      action_1.press(element1).move_to(element2).release()
      action_2.press(element3).wait().release(element3)
      # fire all the added events
      multitouch.add(action_1).add(action_2).perform()
    '''

    def __init__(self, marionette):
        self.multi_actions = []
        self.max_length = 0
        self.marionette = marionette

    def add(self, action):
        '''
        Adds a set of actions to perform.

        :param action: An Actions object.
        '''
        self.multi_actions.append(action.action_chain)
        if len(action.action_chain) > self.max_length:
          self.max_length = len(action.action_chain)
        return self

    def perform(self):
        '''
        Perform all the actions added to this object.
        '''
        return self.marionette._send_message('multiAction', 'ok', value=self.multi_actions, max_length=self.max_length)


class Marionette(object):
    """
    Represents a Marionette connection to a browser or device.
    """

    CONTEXT_CHROME = 'chrome' # non-browser content: windows, dialogs, etc.
    CONTEXT_CONTENT = 'content' # browser content: iframes, divs, etc.
    TIMEOUT_SEARCH = 'implicit'
    TIMEOUT_SCRIPT = 'script'
    TIMEOUT_PAGE = 'page load'

    def __init__(self, host='localhost', port=2828, app=None, app_args=None, bin=None,
                 profile=None, emulator=None, sdcard=None, emulator_img=None,
                 emulator_binary=None, emulator_res=None, connect_to_running_emulator=False,
                 gecko_log=None, homedir=None, baseurl=None, no_window=False, logdir=None,
                 busybox=None, symbols_path=None, timeout=None, socket_timeout=360,
                 device_serial=None, adb_path=None, process_args=None,
                 adb_host=None, adb_port=None):
        self.host = host
        self.port = self.local_port = port
        self.bin = bin
        self.profile = profile
        self.instance = None
        self.session = None
        self.session_id = None
        self.window = None
        self.chrome_window = None
        self.runner = None
        self.emulator = None
        self.extra_emulators = []
        self.baseurl = baseurl
        self.no_window = no_window
        self._test_name = None
        self.timeout = timeout
        self.socket_timeout = socket_timeout
        self.device_serial = device_serial
        self.adb_host = adb_host
        self.adb_port = adb_port

        if bin:
            port = int(self.port)
            if not Marionette.is_port_available(port, host=self.host):
                ex_msg = "%s:%d is unavailable." % (self.host, port)
                raise errors.MarionetteException(message=ex_msg)
            if app:
                # select instance class for the given app
                try:
                    instance_class = geckoinstance.apps[app]
                except KeyError:
                    msg = 'Application "%s" unknown (should be one of %s)'
                    raise NotImplementedError(msg % (app, geckoinstance.apps.keys()))
            else:
                try:
                    config = ConfigParser.RawConfigParser()
                    config.read(os.path.join(os.path.dirname(bin), 'application.ini'))
                    app = config.get('App', 'Name')
                    instance_class = geckoinstance.apps[app.lower()]
                except (ConfigParser.NoOptionError,
                        ConfigParser.NoSectionError,
                        KeyError):
                    instance_class = geckoinstance.GeckoInstance
            self.instance = instance_class(host=self.host, port=self.port,
                                           bin=self.bin, profile=self.profile,
                                           app_args=app_args, symbols_path=symbols_path,
                                           gecko_log=gecko_log)
            self.instance.start()
            assert(self.wait_for_port()), "Timed out waiting for port!"

        if emulator:
            self.runner = B2GEmulatorRunner(b2g_home=homedir,
                                            no_window=self.no_window,
                                            logdir=logdir,
                                            arch=emulator,
                                            sdcard=sdcard,
                                            symbols_path=symbols_path,
                                            binary=emulator_binary,
                                            userdata=emulator_img,
                                            resolution=emulator_res,
                                            profile=self.profile,
                                            adb_path=adb_path,
                                            process_args=process_args)
            self.emulator = self.runner.device
            self.emulator.start()
            self.port = self.emulator.setup_port_forwarding(remote_port=self.port)
            assert(self.emulator.wait_for_port(self.port)), "Timed out waiting for port!"

        if connect_to_running_emulator:
            self.runner = B2GEmulatorRunner(b2g_home=homedir,
                                            logdir=logdir,
                                            process_args=process_args)
            self.emulator = self.runner.device
            self.emulator.connect()
            self.port = self.emulator.setup_port_forwarding(remote_port=self.port)
            assert(self.emulator.wait_for_port(self.port)), "Timed out waiting for port!"

        self.client = MarionetteTransport(self.host, self.port, self.socket_timeout)

        if emulator:
            if busybox:
                self.emulator.install_busybox(busybox=busybox)
            self.emulator.wait_for_system_message(self)

    def cleanup(self):
        if self.session:
            try:
                self.delete_session()
            except (errors.MarionetteException, socket.error, IOError):
                # These exceptions get thrown if the Marionette server
                # hit an exception/died or the connection died. We can
                # do no further server-side cleanup in this case.
                pass
            self.session = None
        if self.runner:
            self.runner.cleanup()
        if self.instance:
            self.instance.close()
        for qemu in self.extra_emulators:
            qemu.emulator.close()

    def __del__(self):
        self.cleanup()

    @staticmethod
    def is_port_available(port, host=''):
        port = int(port)
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        try:
            s.bind((host, port))
            return True
        except socket.error:
            return False
        finally:
            s.close()

    def wait_for_port(self, timeout=60):
        return MarionetteTransport.wait_for_port(self.host,
                                                 self.port,
                                                 timeout=timeout)

    @do_crash_check
    def _send_message(self, command, response_key="ok", **kwargs):
        if not self.session_id and command != "newSession":
            raise errors.MarionetteException("Please start a session")

        message = {"name": command}
        if self.session_id:
            message["sessionId"] = self.session_id
        if kwargs:
            message["parameters"] = kwargs

        try:
            response = self.client.send(message)
        except socket.timeout:
            self.session = None
            self.window = None
            self.client.close()
            raise errors.TimeoutException(
                "Connection timed out", status=errors.ErrorCodes.TIMEOUT)

        # Process any emulator commands that are sent from a script
        # while it's executing.
        while True:
            if response.get("emulator_cmd"):
                response = self._handle_emulator_cmd(response)
                continue;

            if response.get("emulator_shell"):
                response = self._handle_emulator_shell(response)
                continue;

            break;
        if not self.session_id:
            self.session_id = response.get("sessionId", None)

        if response_key in response:
            return response[response_key]
        self._handle_error(response)

    def _handle_emulator_cmd(self, response):
        cmd = response.get("emulator_cmd")
        if not cmd or not self.emulator:
            raise errors.MarionetteException(
                "No emulator in this test to run command against")
        cmd = cmd.encode("ascii")
        result = self.emulator._run_telnet(cmd)
        return self.client.send({"name": "emulatorCmdResult",
                                 "id": response.get("id"),
                                 "result": result})

    def _handle_emulator_shell(self, response):
        args = response.get("emulator_shell")
        if not isinstance(args, list) or not self.emulator:
            raise errors.MarionetteException(
                "No emulator in this test to run shell command against")
        buf = StringIO.StringIO()
        self.emulator.dm.shell(args, buf)
        result = str(buf.getvalue()[0:-1]).rstrip().splitlines()
        buf.close()
        return self.client.send({"name": "emulatorCmdResult",
                                 "id": response.get("id"),
                                 "result": result})

    def _handle_error(self, response):
        if "error" not in response or not isinstance(response["error"], dict):
            raise errors.MarionetteException(
                "Malformed packet, expected key 'error' to be a dict: %s" % response)

        error = response["error"]
        status = error.get("status", 500)
        message = error.get("message")
        stacktrace = error.get("stacktrace")

        # status numbers come from
        # http://code.google.com/p/selenium/wiki/JsonWireProtocol#Response_Status_Codes
        if status == errors.ErrorCodes.NO_SUCH_ELEMENT:
            raise errors.NoSuchElementException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.NO_SUCH_FRAME:
            raise errors.NoSuchFrameException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.STALE_ELEMENT_REFERENCE:
            raise errors.StaleElementException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.ELEMENT_NOT_VISIBLE:
            raise errors.ElementNotVisibleException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.ELEMENT_NOT_ACCESSIBLE:
            raise errors.ElementNotAccessibleException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.INVALID_ELEMENT_STATE:
            raise errors.InvalidElementStateException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.UNKNOWN_ERROR:
            raise errors.MarionetteException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.ELEMENT_IS_NOT_SELECTABLE:
            raise errors.ElementNotSelectableException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.JAVASCRIPT_ERROR:
            raise errors.JavascriptException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.XPATH_LOOKUP_ERROR:
            raise errors.XPathLookupException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.TIMEOUT:
            raise errors.TimeoutException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.NO_SUCH_WINDOW:
            raise errors.NoSuchWindowException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.INVALID_COOKIE_DOMAIN:
            raise errors.InvalidCookieDomainException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.UNABLE_TO_SET_COOKIE:
            raise errors.UnableToSetCookieException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.NO_ALERT_OPEN:
            raise errors.NoAlertPresentException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.SCRIPT_TIMEOUT:
            raise errors.ScriptTimeoutException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.INVALID_SELECTOR \
             or status == errors.ErrorCodes.INVALID_XPATH_SELECTOR \
             or status == errors.ErrorCodes.INVALID_XPATH_SELECTOR_RETURN_TYPER:
            raise errors.InvalidSelectorException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.MOVE_TARGET_OUT_OF_BOUNDS:
            raise errors.MoveTargetOutOfBoundsException(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.FRAME_SEND_NOT_INITIALIZED_ERROR:
            raise errors.FrameSendNotInitializedError(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.FRAME_SEND_FAILURE_ERROR:
            raise errors.FrameSendFailureError(message=message, status=status, stacktrace=stacktrace)
        elif status == errors.ErrorCodes.UNSUPPORTED_OPERATION:
            raise errors.UnsupportedOperationException(message=message, status=status, stacktrace=stacktrace)
        else:
            raise errors.MarionetteException(message=message, status=status, stacktrace=stacktrace)

    def _reset_timeouts(self):
        if self.timeout is not None:
            self.timeouts(self.TIMEOUT_SEARCH, self.timeout)
            self.timeouts(self.TIMEOUT_SCRIPT, self.timeout)
            self.timeouts(self.TIMEOUT_PAGE, self.timeout)
        else:
            self.timeouts(self.TIMEOUT_PAGE, 30000)

    def check_for_crash(self):
        returncode = None
        name = None
        crashed = False
        if self.runner:
            if self.runner.check_for_crashes(test_name=self.test_name):
                returncode = self.emulator.proc.returncode
                name = 'emulator'
                crashed = True
        elif self.instance:
            if self.instance.runner.check_for_crashes(
                    test_name=self.test_name):
                crashed = True
        if returncode is not None:
            print ('PROCESS-CRASH | %s | abnormal termination with exit code %d' %
                (name, returncode))
        return crashed

    def enforce_gecko_prefs(self, prefs):
        """
        Checks if the running instance has the given prefs. If not, it will kill the
        currently running instance, and spawn a new instance with the requested preferences.

        : param prefs: A dictionary whose keys are preference names.
        """
        if not self.instance:
            raise errors.MarionetteException("enforce_gecko_prefs can only be called " \
                                             "on gecko instances launched by Marionette")
        pref_exists = True
        self.set_context(self.CONTEXT_CHROME)
        for pref, value in prefs.iteritems():
            if type(value) is not str:
                value = json.dumps(value)
            pref_exists = self.execute_script("""
            let prefInterface = Components.classes["@mozilla.org/preferences-service;1"]
                                          .getService(Components.interfaces.nsIPrefBranch);
            let pref = '%s';
            let value = '%s';
            let type = prefInterface.getPrefType(pref);
            switch(type) {
                case prefInterface.PREF_STRING:
                    return value == prefInterface.getCharPref(pref).toString();
                case prefInterface.PREF_BOOL:
                    return value == prefInterface.getBoolPref(pref).toString();
                case prefInterface.PREF_INT:
                    return value == prefInterface.getIntPref(pref).toString();
                case prefInterface.PREF_INVALID:
                    return false;
            }
            """ % (pref, value))
            if not pref_exists:
                break
        self.set_context(self.CONTEXT_CONTENT)
        if not pref_exists:
            self.delete_session()
            self.instance.restart(prefs)
            assert(self.wait_for_port()), "Timed out waiting for port!"
            self.start_session()
            self._reset_timeouts()

    def restart(self, clean=False):
        """
        This will terminate the currently running instance, and spawn a new instance
        with the same profile and then reuse the session id when creating a session again.

        : param prefs: A dictionary whose keys are preference names.
        """
        if not self.instance:
            raise errors.MarionetteException("restart can only be called " \
                                             "on gecko instances launched by Marionette")
        self.delete_session()
        self.instance.restart(clean=clean)
        assert(self.wait_for_port()), "Timed out waiting for port!"
        self.start_session(session_id=self.session_id)
        self._reset_timeouts()

    def absolute_url(self, relative_url):
        '''
        Returns an absolute url for files served from Marionette's www directory.

        :param relative_url: The url of a static file, relative to Marionette's www directory.
        '''
        return "%s%s" % (self.baseurl, relative_url)

    def start_session(self, desired_capabilities=None, session_id=None, timeout=60):
        """Create a new Marionette session.

        This method must be called before performing any other action.

        :param desired_capabilities: An optional dict of desired
            capabilities.  This is currently ignored.
        :param timeout: Timeout in seconds for the server to be ready.
        :param session_id: unique identifier for the session. If no session id is
            passed in then one will be generated by the marionette server.

        :returns: A dict of the capabilities offered."""
        self.wait_for_port(timeout=timeout)
        self.session = self._send_message('newSession', 'value', capabilities=desired_capabilities, session_id=session_id)
        self.b2g = 'b2g' in self.session
        return self.session

    @property
    def test_name(self):
        return self._test_name

    @test_name.setter
    def test_name(self, test_name):
        if self._send_message('setTestName', 'ok', value=test_name):
            self._test_name = test_name

    def delete_session(self):
        """Close the current session and disconnect from the server."""
        response = self._send_message('deleteSession', 'ok')
        self.session_id = None
        self.session = None
        self.window = None
        self.client.close()
        return response

    @property
    def session_capabilities(self):
        '''
        A JSON dictionary representing the capabilities of the current session.
        '''
        response = self._send_message('getSessionCapabilities', 'value')
        return response

    def set_script_timeout(self, timeout):
        '''
        Sets the maximum number of ms that an asynchronous script is allowed to run.

        If a script does not return in the specified amount of time, a
        ScriptTimeoutException is raised.

        :param timeout: The maximum number of milliseconds an asynchronous
         script can run without causing an ScriptTimeoutException to be raised
        '''
        response = self._send_message('setScriptTimeout', 'ok', ms=timeout)
        return response

    def set_search_timeout(self, timeout):
        '''
        Sets a timeout for the find methods.

        When searching for an element using either
        :class:`Marionette.find_element` or :class:`Marionette.find_elements`,
        the method will continue trying to locate the element for up to timeout
        ms. This can be useful if, for example, the element you're looking for
        might not exist immediately, because it belongs to a page which is
        currently being loaded.

        :param timeout: Timeout in milliseconds.
        '''
        response = self._send_message('setSearchTimeout', 'ok', ms=timeout)
        return response

    @property
    def current_window_handle(self):
        """Get the current window's handle.

        Returns an opaque server-assigned identifier to this window
        that uniquely identifies it within this Marionette instance.
        This can be used to switch to this window at a later point.

        :returns: unique window handle
        :rtype: string

        """
        self.window = self._send_message("getWindowHandle", "value")
        return self.window

    @property
    def current_chrome_window_handle(self):
        """Get the current chrome window's handle. Corresponds to
        a chrome window that may itself contain tabs identified by
        window_handles.

        Returns an opaque server-assigned identifier to this window
        that uniquely identifies it within this Marionette instance.
        This can be used to switch to this window at a later point.

        :returns: unique window handle
        :rtype: string

        """
        self.chrome_window = self._send_message("getCurrentChromeWindowHandle", "value")
        return self.chrome_window


    def get_window_position(self):
        """Get the current window's position
           Return a dictionary with the keys x and y
           :returns: a dictionary with x and y
        """
        return self._send_message("getWindowPosition", "value")

    def set_window_position(self, x, y):
        """
           Set the position of the current window
            :param x: x coordinate for the top left of the window
            :param y: y coordinate for the top left of the window
        """
        response = self._send_message("setWindowPosition", "ok", x=x, y=y)
        return response

    @property
    def title(self):
        '''
        Current title of the active window.
        '''
        response = self._send_message('getTitle', 'value')
        return response

    @property
    def window_handles(self):
        """Get list of windows in the current context.

        If called in the content context it will return a list of
        references to all available browser windows.  Called in the
        chrome context, it will list all available windows, not just
        browser windows (e.g. not just navigator.browser).

        Each window handle is assigned by the server, and the list of
        strings returned does not have a guaranteed ordering.

        :returns: unordered list of unique window handles as strings

        """

        response = self._send_message("getWindowHandles", "value")
        return response

    @property
    def chrome_window_handles(self):
        """Get a list of currently open chrome windows.

        Each window handle is assigned by the server, and the list of
        strings returned does not have a guaranteed ordering.

        :returns: unordered list of unique window handles as strings

        """

        response = self._send_message("getChromeWindowHandles", "value")
        return response


    @property
    def page_source(self):
        '''
        A string representation of the DOM.
        '''
        response = self._send_message('getPageSource', 'value')
        return response

    def close(self):
        """Close the current window, ending the session if it's the last
        window currently open.

        On B2G this method is a noop and will return immediately.

        """

        response = self._send_message("close", "ok")
        return response

    def close_chrome_window(self):
        """Close the currently selected chrome window, ending the session
        if it's the last window open.

        On B2G this method is a noop and will return immediately.

        """

        response = self._send_message("closeChromeWindow", "ok")
        return response

    def set_context(self, context):
        '''
        Sets the context that Marionette commands are running in.

        :param context: Context, may be one of the class properties
         `CONTEXT_CHROME` or `CONTEXT_CONTENT`.

        Usage example::

          marionette.set_context(marionette.CONTEXT_CHROME)
        '''
        assert(context == self.CONTEXT_CHROME or context == self.CONTEXT_CONTENT)
        return self._send_message('setContext', 'ok', value=context)

    @contextmanager
    def using_context(self, context):
        '''
        Sets the context that Marionette commands are running in using
        a `with` statement. The state of the context on the server is
        saved before entering the block, and restored upon exiting it.

        :param context: Context, may be one of the class properties
         `CONTEXT_CHROME` or `CONTEXT_CONTENT`.

        Usage example::

          with marionette.using_context(marionette.CONTEXT_CHROME):
              # chrome scope
              ... do stuff ...
        '''
        scope = self._send_message('getContext', 'value')
        self.set_context(context)
        try:
            yield
        finally:
            self.set_context(scope)

    def switch_to_window(self, window_id):
        '''
        Switch to the specified window; subsequent commands will be directed at the new window.

        :param window_id: The id or name of the window to switch to.
        '''
        response = self._send_message('switchToWindow', 'ok', name=window_id)
        self.window = window_id
        return response

    def get_active_frame(self):
        '''
        Returns an HTMLElement representing the frame Marionette is currently acting on.
        '''
        response = self._send_message('getActiveFrame', 'value')
        if response:
            return HTMLElement(self, response)
        return None

    def switch_to_default_content(self):
        '''
        Switch the current context to page's default content.
        '''
        return self.switch_to_frame()

    def switch_to_frame(self, frame=None, focus=True):
        '''
        Switch the current context to the specified frame. Subsequent commands will operate in the context of the specified frame, if applicable.

        :param frame: A reference to the frame to switch to: this can be an HTMLElement, an index, name or an id attribute. If you call switch_to_frame() without an argument, it will switch to the top-level frame.
        :param focus: A boolean value which determins whether to focus the frame that we just switched to.
        '''
        if isinstance(frame, HTMLElement):
            response = self._send_message('switchToFrame', 'ok', element=frame.id, focus=focus)
        else:
            response = self._send_message('switchToFrame', 'ok', id=frame, focus=focus)
        return response

    def get_url(self):
        """Get a string representing the current URL.

        On Desktop this returns a string representation of the URL of
        the current top level browsing context.  This is equivalent to
        document.location.href.

        When in the context of the chrome, this returns the canonical
        URL of the current resource.

        :returns: string representation of URL

        """

        response = self._send_message("getCurrentUrl", "value")
        return response

    def get_window_type(self):
        '''
        Gets the windowtype attribute of the window Marionette is currently acting on.

        This command only makes sense in a chrome context. You might use this
        method to distinguish a browser window from an editor window.
        '''
        response = self._send_message('getWindowType', 'value')
        return response

    def navigate(self, url):
        """Navigate to to given URL.

        This will follow redirects issued by the server.  When the
        method returns is based on the page load strategy that the
        user has selected.

        Documents that contain a META tag with the "http-equiv"
        attribute set to "refresh" will return if the timeout is
        greater than 1 second and the other criteria for determining
        whether a page is loaded are met.  When the refresh period is
        1 second or less and the page load strategy is "normal" or
        "conservative", it will wait for the page to complete loading
        before returning.

        If any modal dialog box, such as those opened on
        window.onbeforeunload or window.alert, is opened at any point
        in the page load, it will return immediately.

        If a 401 response is seen by the browser, it will return
        immediately.  That is, if BASIC, DIGEST, NTLM or similar
        authentication is required, the page load is assumed to be
        complete.  This does not include FORM-based authentication.

        :param url: The url to navigate to.

        """

        response = self._send_message("get", "ok", url=url)
        return response

    def timeouts(self, timeout_type, ms):
        assert(timeout_type == self.TIMEOUT_SEARCH or timeout_type == self.TIMEOUT_SCRIPT or timeout_type == self.TIMEOUT_PAGE)
        response = self._send_message('timeouts', 'ok', type=timeout_type, ms=ms)
        return response

    def go_back(self):
        '''
        Causes the browser to perform a back navigation.
        '''
        response = self._send_message('goBack', 'ok')
        return response

    def go_forward(self):
        '''
        Causes the browser to perform a forward navigation.
        '''
        response = self._send_message('goForward', 'ok')
        return response

    def refresh(self):
        '''
        Causes the browser to perform to refresh the current page.
        '''
        response = self._send_message('refresh', 'ok')
        return response

    def wrapArguments(self, args):
        if isinstance(args, list):
            wrapped = []
            for arg in args:
                wrapped.append(self.wrapArguments(arg))
        elif isinstance(args, dict):
            wrapped = {}
            for arg in args:
                wrapped[arg] = self.wrapArguments(args[arg])
        elif type(args) == HTMLElement:
            wrapped = {'ELEMENT': args.id }
        elif (isinstance(args, bool) or isinstance(args, basestring) or
              isinstance(args, int) or isinstance(args, float) or args is None):
            wrapped = args

        return wrapped

    def unwrapValue(self, value):
        if isinstance(value, list):
            unwrapped = []
            for item in value:
                unwrapped.append(self.unwrapValue(item))
        elif isinstance(value, dict):
            unwrapped = {}
            for key in value:
                if key == 'ELEMENT':
                    unwrapped = HTMLElement(self, value[key])
                else:
                    unwrapped[key] = self.unwrapValue(value[key])
        else:
            unwrapped = value

        return unwrapped

    def execute_js_script(self, script, script_args=None, async=True,
                          new_sandbox=True, special_powers=False,
                          script_timeout=None, inactivity_timeout=None,
                          filename=None):
        if script_args is None:
            script_args = []
        args = self.wrapArguments(script_args)
        response = self._send_message('executeJSScript',
                                      'value',
                                      script=script,
                                      args=args,
                                      async=async,
                                      newSandbox=new_sandbox,
                                      specialPowers=special_powers,
                                      scriptTimeout=script_timeout,
                                      inactivityTimeout=inactivity_timeout,
                                      filename=filename,
                                      line=None)
        return self.unwrapValue(response)

    def execute_script(self, script, script_args=None, new_sandbox=True,
                       special_powers=False, script_timeout=None):
        '''
        Executes a synchronous JavaScript script, and returns the result (or None if the script does return a value).

        The script is executed in the context set by the most recent
        set_context() call, or to the CONTEXT_CONTENT context if set_context()
        has not been called.

        :param script: A string containing the JavaScript to execute.
        :param script_args: A list of arguments to pass to the script.
        :param special_powers: Whether or not you want access to SpecialPowers
         in your script. Set to False by default because it shouldn't really
         be used, since you already have access to chrome-level commands if you
         set context to chrome and do an execute_script. This method was added
         only to help us run existing Mochitests.
        :param new_sandbox: If False, preserve global variables from the last
         execute_*script call. This is True by default, in which case no
         globals are preserved.

        Simple usage example:

        ::

          result = marionette.execute_script("return 1;")
          assert result == 1

        You can use the `script_args` parameter to pass arguments to the
        script:

        ::

          result = marionette.execute_script("return arguments[0] + arguments[1];",
                                             script_args=[2, 3])
          assert result == 5
          some_element = marionette.find_element("id", "someElement")
          sid = marionette.execute_script("return arguments[0].id;", script_args=[some_element])
          assert some_element.get_attribute("id") == sid

        Scripts wishing to access non-standard properties of the window object must use
        window.wrappedJSObject:

        ::

          result = marionette.execute_script("""
            window.wrappedJSObject.test1 = 'foo';
            window.wrappedJSObject.test2 = 'bar';
            return window.wrappedJSObject.test1 + window.wrappedJSObject.test2;
            """)
          assert result == "foobar"

        Global variables set by individual scripts do not persist between
        script calls by default.  If you wish to persist data between script
        calls, you can set new_sandbox to False on your next call, and add any
        new variables to a new 'global' object like this:

        ::

          marionette.execute_script("global.test1 = 'foo';")
          result = self.marionette.execute_script("return global.test1;", new_sandbox=False)
          assert result == 'foo'

        '''
        if script_args is None:
            script_args = []
        args = self.wrapArguments(script_args)
        stack = traceback.extract_stack()
        frame = stack[-2:-1][0] # grab the second-to-last frame
        response = self._send_message('executeScript',
                                      'value',
                                      script=script,
                                      args=args,
                                      newSandbox=new_sandbox,
                                      specialPowers=special_powers,
                                      scriptTimeout=script_timeout,
                                      line=int(frame[1]),
                                      filename=os.path.basename(frame[0]))
        return self.unwrapValue(response)

    def execute_async_script(self, script, script_args=None, new_sandbox=True, special_powers=False, script_timeout=None):
        '''
        Executes an asynchronous JavaScript script, and returns the result (or None if the script does return a value).

        The script is executed in the context set by the most recent
        set_context() call, or to the CONTEXT_CONTENT context if set_context()
        has not been called.

        :param script: A string containing the JavaScript to execute.
        :param script_args: A list of arguments to pass to the script.
        :param special_powers: Whether or not you want access to SpecialPowers
         in your script. Set to False by default because it shouldn't really
         be used, since you already have access to chrome-level commands if you
         set context to chrome and do an execute_script. This method was added
         only to help us run existing Mochitests.
        :param new_sandbox: If False, preserve global variables from the last
         execute_*script call. This is True by default, in which case no
         globals are preserved.

        Usage example:

        ::

          marionette.set_script_timeout(10000) # set timeout period of 10 seconds
          result = self.marionette.execute_async_script("""
            // this script waits 5 seconds, and then returns the number 1
            setTimeout(function() {
              marionetteScriptFinished(1);
            }, 5000);
          """)
          assert result == 1
        '''
        if script_args is None:
            script_args = []
        args = self.wrapArguments(script_args)
        stack = traceback.extract_stack()
        frame = stack[-2:-1][0] # grab the second-to-last frame
        response = self._send_message('executeAsyncScript',
                                      'value',
                                      script=script,
                                      args=args,
                                      newSandbox=new_sandbox,
                                      specialPowers=special_powers,
                                      scriptTimeout=script_timeout,
                                      line=int(frame[1]),
                                      filename=os.path.basename(frame[0]))
        return self.unwrapValue(response)

    def find_element(self, method, target, id=None):
        '''
        Returns an HTMLElement instances that matches the specified method and target in the current context.

        An HTMLElement instance may be used to call other methods on the
        element, such as click().  If no element is immediately found, the
        attempt to locate an element will be repeated for up to the amount of
        time set by set_search_timeout(). If multiple elements match the given
        criteria, only the first is returned. If no element matches, a
        NoSuchElementException will be raised.

        :param method: The method to use to locate the element; one of: "id",
                       "name", "class name", "tag name", "css selector", "link text",
                       "partial link text", "xpath", "anon" and "anon attribute".
                       Note that the "name", "link text" and
                       "partial link test" methods are not supported in the chrome dom.
        :param target: The target of the search.  For example, if method =
                       "tag", target might equal "div".  If method = "id", target would be
                       an element id.
        :param id: If specified, search for elements only inside the element
                   with the specified id.
        '''
        kwargs = { 'value': target, 'using': method }
        if id:
            kwargs['element'] = id
        response = self._send_message('findElement', 'value', **kwargs)
        element = HTMLElement(self, response['ELEMENT'])
        return element

    def find_elements(self, method, target, id=None):
        '''
        Returns a list of all HTMLElement instances that match the specified method and target in the current context.

        An HTMLElement instance may be used to call other methods on the
        element, such as click().  If no element is immediately found, the
        attempt to locate an element will be repeated for up to the amount of
        time set by set_search_timeout().

        :param method: The method to use to locate the elements; one of:
                       "id", "name", "class name", "tag name", "css selector", "link text",
                       "partial link text", "xpath", "anon" and "anon attribute".
                       Note that the "name", "link text" and
                       "partial link test" methods are not supported in the chrome dom.
        :param target: The target of the search.  For example, if method =
                       "tag", target might equal "div".  If method = "id", target would be
                       an element id.
        :param id: If specified, search for elements only inside the element
                   with the specified id.
        '''
        kwargs = { 'value': target, 'using': method }
        if id:
            kwargs['element'] = id
        response = self._send_message('findElements', 'value', **kwargs)
        assert(isinstance(response, list))
        elements = []
        for x in response:
            elements.append(HTMLElement(self, x))
        return elements

    def get_active_element(self):
        response = self._send_message('getActiveElement', 'value')
        return HTMLElement(self, response)

    def log(self, msg, level=None):
        '''
        Stores a timestamped log message in the Marionette server for later retrieval.

        :param msg: String with message to log.
        :param level: String with log level (e.g. "INFO" or "DEBUG"). If None,
         defaults to "INFO".
        '''
        return self._send_message('log', 'ok', value=msg, level=level)

    def get_logs(self):
        '''
        Returns the list of logged messages.

        Each log message is an array with three string elements: the level,
        the message, and a date.

        Usage example:

        ::

          marionette.log("I AM INFO")
          marionette.log("I AM ERROR", "ERROR")
          logs = marionette.get_logs()
          assert logs[0][1] == "I AM INFO"
          assert logs[1][1] == "I AM ERROR"
        '''
        return self._send_message('getLogs', 'value')

    def import_script(self, js_file):
        '''
        Imports a script into the scope of the execute_script and execute_async_script calls.

        This is particularly useful if you wish to import your own libraries.

        :param js_file: Filename of JavaScript file to import.

        For example, Say you have a script, importfunc.js, that contains:

        ::

          let testFunc = function() { return "i'm a test function!";};

        Assuming this file is in the same directory as the test, you could do
        something like:

        ::

          js = os.path.abspath(os.path.join(__file__, os.path.pardir, "importfunc.js"))
          marionette.import_script(js)
          assert "i'm a test function!" == self.marionette.execute_script("return testFunc();")
        '''
        js = ''
        with open(js_file, 'r') as f:
            js = f.read()
        return self._send_message('importScript', 'ok', script=js)

    def clear_imported_scripts(self):
        '''
        Clears all imported scripts in this context, ie: calling clear_imported_scripts in chrome
        context will clear only scripts you imported in chrome, and will leave the scripts
        you imported in content context.
        '''
        return self._send_message('clearImportedScripts', 'ok')

    def add_cookie(self, cookie):
        """
        Adds a cookie to your current session.

        :param cookie: A dictionary object, with required keys - "name" and
         "value"; optional keys - "path", "domain", "secure", "expiry".

        Usage example:

        ::

          driver.add_cookie({'name': 'foo', 'value': 'bar'})
          driver.add_cookie({'name': 'foo', 'value': 'bar', 'path': '/'})
          driver.add_cookie({'name': 'foo', 'value': 'bar', 'path': '/',
                             'secure': True})
        """
        return self._send_message('addCookie', 'ok', cookie=cookie)

    def delete_all_cookies(self):
        """
        Delete all cookies in the scope of the current session.

        Usage example:

        ::

          driver.delete_all_cookies()
        """
        return self._send_message('deleteAllCookies', 'ok')

    def delete_cookie(self, name):
        """
        Delete a cookie by its name.

        :param name: Name of cookie to delete.

        Usage example:

        ::

          driver.delete_cookie('foo')
        """
        return self._send_message('deleteCookie', 'ok', name=name);

    def get_cookie(self, name):
        """
        Get a single cookie by name. Returns the cookie if found, None if not.

        :param name: Name of cookie to get.
        """
        cookies = self.get_cookies()
        for cookie in cookies:
            if cookie['name'] == name:
                return cookie
        return None

    def get_cookies(self):
        """Get all the cookies for the current domain.

        This is the equivalent of calling `document.cookie` and
        parsing the result.

        :returns: A set of cookies for the current domain.

        """

        return self._send_message("getCookies", "value")

    @property
    def application_cache(self):
        return ApplicationCache(self)

    def screenshot(self, element=None, highlights=None, format="base64"):
        """Takes a screenshot of a web element or the current frame.

        The screen capture is returned as a lossless PNG image encoded
        as a base 64 string by default. If the `element` argument is defined the
        capture area will be limited to the bounding box of that
        element.  Otherwise, the capture area will be the bounding box
        of the current frame.

        :param element: The element to take a screenshot of.  If None, will
            take a screenshot of the current frame.

        :param highlights: A list of HTMLElement objects to draw a red
            box around in the returned screenshot.

        :param format: if "base64" (the default), returns the screenshot
            as a base64-string. If "binary", the data is decoded and
            returned as raw binary.

        """

        if element:
            element = element.id
        lights = None
        if highlights:
            lights = [highlight.id for highlight in highlights]
        screenshot_data = self._send_message("takeScreenshot", "value",
                                  id=element, highlights=lights)
        if format == 'base64':
            return screenshot_data
        elif format == 'binary':
            return base64.b64decode(screenshot_data.encode('ascii'))
        else:
            raise ValueError("format parameter must be either 'base64'"
                             " or 'binary', not {0}".format(repr(format)))

    @property
    def orientation(self):
        """Get the current browser orientation.

        Will return one of the valid primary orientation values
        portrait-primary, landscape-primary, portrait-secondary, or
        landscape-secondary.

        """
        return self._send_message("getScreenOrientation", "value")

    def set_orientation(self, orientation):
        """Set the current browser orientation.

        The supplied orientation should be given as one of the valid
        orientation values.  If the orientation is unknown, an error
        will be raised.

        Valid orientations are "portrait" and "landscape", which fall
        back to "portrait-primary" and "landscape-primary"
        respectively, and "portrait-secondary" as well as
        "landscape-secondary".

        :param orientation: The orientation to lock the screen in.

        """
        self._send_message("setScreenOrientation", "ok", orientation=orientation)
        if self.emulator:
            self.emulator.screen.orientation = orientation.lower()

    @property
    def window_size(self):
        """Get the current browser window size.

        Will return the current browser window size in pixels. Refers to
        window outerWidth and outerHeight values, which include scroll bars,
        title bars, etc.

        :returns: dictionary representation of current window width and height

        """
        return self._send_message("getWindowSize", "value")

    def set_window_size(self, width, height):
        """Resize the browser window currently in focus.

        The supplied width and height values refer to the window outerWidth
        and outerHeight values, which include scroll bars, title bars, etc.

        An error will be returned if the requested window size would result
        in the window being in the maximised state.

        :param width: The width to resize the window to.
        :param height: The height to resize the window to.

        """
        self._send_message("setWindowSize", "ok", width=width, height=height)

    def maximize_window(self):
        """ Resize the browser window currently receiving commands. The action
        should be equivalent to the user pressing the the maximize button
        """

        return self._send_message("maximizeWindow", "ok")
