# 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 asyncio
import contextlib
import time
from base64 import b64decode
from io import BytesIO
from urllib.parse import quote

import pytest
import webdriver
from PIL import Image
from webdriver.bidi.error import InvalidArgumentException, NoSuchFrameException
from webdriver.bidi.modules.script import ContextTarget


class Client:
    def __init__(self, request, session, event_loop):
        self.request = request
        self.session = session
        self.event_loop = event_loop
        self.subscriptions = {}
        self.content_blocker_loaded = False

    @property
    def current_url(self):
        return self.session.url

    @property
    def alert(self):
        return self.session.alert

    @property
    def context(self):
        return self.session.send_session_command("GET", "moz/context")

    @context.setter
    def context(self, context):
        self.session.send_session_command("POST", "moz/context", {"context": context})

    @contextlib.contextmanager
    def using_context(self, context):
        orig_context = self.context
        needs_change = context != orig_context

        if needs_change:
            self.context = context

        try:
            yield
        finally:
            if needs_change:
                self.context = orig_context

    def set_screen_size(self, width, height):
        if self.session.capabilities.get("setWindowRect"):
            self.session.window.size = (width, height)
            return True
        return False

    def get_element_screen_position(self, element):
        return self.execute_script(
            """
          const e = arguments[0];
          const b = e.getClientRects()[0];
          const leftChrome = window.mozInnerScreenX;
          const topChrome = window.mozInnerScreenY;
          const x = window.scrollX + leftChrome + b.x;
          const y = window.scrollY + topChrome + b.y;
          return [x, y];
        """,
            element,
        )

    async def send_apz_scroll_gesture(
        self, units, element=None, offset=None, coords=None
    ):
        if coords is None:
            if element is None:
                raise ValueError("require coords and/or element")
            coords = self.get_element_screen_position(element)
        if offset is not None:
            coords[0] += offset[0]
            coords[1] += offset[1]
        with self.using_context("chrome"):
            return self.execute_async_script(
                """
                const [units, coords, done] = arguments;
                const { devicePixelRatio, windowUtils } = window;
                const resolution = windowUtils.getResolution();
                const toScreenCoords = x => x * devicePixelRatio * resolution;

                // based on nativeVerticalWheelEventMsg()
                let msg = 4; // linux default
                switch (Services.appinfo.OS) {
                  case "WINNT":
                    msg = 0x0115; // WM_VSCROLL
                    break;
                  case "Darwin":
                    msg = 1; // use a gesture; don't synthesize a wheel scroll
                    break;
                }

                windowUtils.sendNativeMouseScrollEvent(
                    toScreenCoords(coords[0]),
                    toScreenCoords(coords[1]),
                    msg,
                    0,
                    units,
                    0,
                    0,
                    0,
                    document.documentElement,
                    () => { done(); },
                );
            """,
                units,
                coords,
            )

    async def send_apz_mouse_event(
        self, event_type, coords=None, element=None, button=0
    ):
        # note: use button=2 for context menu/right click (0 is left button)
        if event_type == "down":
            message = "BUTTON_DOWN"
        elif event_type == "up":
            message = "BUTTON_UP"
        elif event_type == "move":
            message = "MOVE"
        else:
            raise ValueError("event_type must be 'down', 'up' or 'move'")
        if coords is None:
            if element is None:
                raise ValueError("require coords and/or element")
            coords = self.get_element_screen_position(element)
        with self.using_context("chrome"):
            return self.execute_async_script(
                """
                const [coords, message, button, done] = arguments;
                const { devicePixelRatio, windowUtils } = window;
                const resolution = windowUtils.getResolution();
                const toScreenCoords = x => x * devicePixelRatio * resolution;
                windowUtils.sendNativeMouseEvent(
                    toScreenCoords(coords[0]),
                    toScreenCoords(coords[1]),
                    windowUtils[`NATIVE_MOUSE_MESSAGE_${message}`],
                    button,
                    0,
                    window.document.documentElement,
                    () => { done(coords); },
                );
            """,
                coords,
                message,
                button,
            )

    async def apz_down(self, **kwargs):
        return await self.send_apz_mouse_event("down", **kwargs)

    async def apz_up(self, **kwargs):
        return await self.send_apz_mouse_event("up", **kwargs)

    async def apz_move(self, **kwargs):
        return await self.send_apz_mouse_event("move", **kwargs)

    async def apz_click(self, **kwargs):
        await self.apz_down(**kwargs)
        return await self.apz_up(**kwargs)

    def apz_scroll(self, element, dx=0, dy=0, dz=0):
        pt = self.get_element_screen_position(element)
        with self.using_context("chrome"):
            return self.execute_script(
                """
                const [pt, delta] = arguments;
                const windowUtils = window.windowUtils;
                const scale = window.devicePixelRatio;
                const resolution = windowUtils.getResolution();
                const toScreenCoords = x => x * scale * resolution;
                const coords = pt.map(toScreenCoords);
                window.windowUtils.sendWheelEvent(
                    coords[0],
                    coords[1],
                    delta[0],
                    delta[1],
                    delta[2],
                    WheelEvent.DOM_DELTA_PIXEL,
                    0,
                    delta[0] > 0 ? 1 : -1,
                    delta[1] > 0 ? 1 : -1,
                    undefined,
                );
            """,
                pt,
                [dx, dy, dz],
            )

    def wait_for_content_blocker(self):
        if not self.content_blocker_loaded:
            with self.using_context("chrome"):
                self.session.execute_async_script(
                    """
                    const done = arguments[0],
                          signal = "safebrowsing-update-finished";
                    function finish() {
                        Services.obs.removeObserver(finish, signal);
                        done();
                    }
                    Services.obs.addObserver(finish, signal);
                """
                )
                self.content_blocker_loaded = True

    @property
    def keyboard(self):
        return self.session.actions.sequence("key", "keyboard_id")

    @property
    def mouse(self):
        return self.session.actions.sequence(
            "pointer", "pointer_id", {"pointerType": "mouse"}
        )

    @property
    def pen(self):
        return self.session.actions.sequence(
            "pointer", "pointer_id", {"pointerType": "pen"}
        )

    @property
    def touch(self):
        return self.session.actions.sequence(
            "pointer", "pointer_id", {"pointerType": "touch"}
        )

    @property
    def wheel(self):
        return self.session.actions.sequence("wheel", "wheel_id")

    @property
    def modifier_key(self):
        if self.session.capabilities["platformName"] == "mac":
            return "\ue03d"  # meta (command)
        else:
            return "\ue009"  # control

    def inline(self, doc):
        return f"data:text/html;charset=utf-8,{quote(doc)}"

    async def top_context(self):
        contexts = await self.session.bidi_session.browsing_context.get_tree()
        return contexts[0]

    async def subscribe(self, events):
        if type(events) is not list:
            events = [events]

        must_sub = []
        for event in events:
            if not event in self.subscriptions:
                must_sub.append(event)
                self.subscriptions[event] = 1
            else:
                self.subscriptions[event] += 1

        if must_sub:
            await self.session.bidi_session.session.subscribe(events=must_sub)

    async def unsubscribe(self, events):
        if type(events) is not list:
            events = [events]

        must_unsub = []
        for event in events:
            self.subscriptions[event] -= 1
            if not self.subscriptions[event]:
                must_unsub.append(event)

        if must_unsub:
            try:
                await self.session.bidi_session.session.unsubscribe(events=must_unsub)
            except (InvalidArgumentException, NoSuchFrameException):
                pass

    async def wait_for_events(self, events, checkFn=None, timeout=None):
        if type(events) is not list:
            events = [events]

        if timeout is None:
            timeout = 10

        future = self.event_loop.create_future()
        remove_listeners = []

        async def on_event(event, data):
            val = data
            if checkFn:
                val = await checkFn(event, data)
                if val is None:
                    return
            for remover in remove_listeners:
                remover()
            await self.unsubscribe(events)
            future.set_result(val)

        for event in events:
            remove_listeners.append(
                self.session.bidi_session.add_event_listener(event, on_event)
            )
        await self.subscribe(events)
        return await asyncio.wait_for(future, timeout=timeout)

    async def get_iframe_by_url(self, url):
        def check_children(children):
            for child in children:
                if "url" in child and url in child["url"]:
                    return child
            for child in children:
                if "children" in child:
                    frame = check_children(child["children"])
                    if frame:
                        return frame
            return None

        tree = await self.session.bidi_session.browsing_context.get_tree()
        for top in tree:
            frame = check_children(top["children"])
            if frame is not None:
                return frame

        return None

    async def is_iframe(self, context):
        def check_children(children):
            for child in children:
                if "context" in child and child["context"] == context:
                    return True
                if "children" in child:
                    return check_children(child["children"])
            return False

        for top in await self.session.bidi_session.browsing_context.get_tree():
            if check_children(top["children"]):
                return True
        return False

    async def wait_for_iframe_loaded(self, url, timeout=None):
        async def wait_for_url(_, data):
            if url in data["url"] and await self.is_iframe(data["context"]):
                return data["context"]
            return None

        return self.wait_for_events("browsingContext.load", wait_for_url)

    async def run_script_in_context(self, script, context=None, sandbox=None):
        if not context:
            context = (await self.top_context())["context"]
        target = ContextTarget(context, sandbox)
        return await self.session.bidi_session.script.evaluate(
            expression=script,
            target=target,
            await_promise=False,
        )

    async def run_script(
        self, script, *args, await_promise=False, context=None, sandbox=None
    ):
        if not context:
            context = (await self.top_context())["context"]
        target = ContextTarget(context, sandbox)
        val = await self.session.bidi_session.script.call_function(
            arguments=self.wrap_script_args(args),
            await_promise=await_promise,
            function_declaration=script,
            target=target,
        )
        if val and "value" in val:
            return val["value"]
        return val

    def await_script(self, script, *args, **kwargs):
        return self.run_script(script, *args, **kwargs, await_promise=True)

    async def await_interventions_started(self):
        interventionsOn = self.request.node.get_closest_marker("with_interventions")
        shimsOn = self.request.node.get_closest_marker("with_shims")

        if not interventionsOn and not shimsOn:
            print("Not waiting for interventions/shims")
            return

        waitFor = "interventions" if interventionsOn else "shims"

        print("Waiting for", waitFor, "to be ready")
        context = await self.session.bidi_session.browsing_context.create(
            type_hint="tab", background=True
        )
        await self.session.bidi_session.browsing_context.navigate(
            context=context["context"],
            url="about:compat",
            wait="interactive",
        )
        await self.session.bidi_session.script.evaluate(
            expression=f"window.browser.extension.getBackgroundPage().{waitFor}.ready()",
            target=ContextTarget(context["context"]),
            await_promise=True,
        )
        await self.session.bidi_session.browsing_context.close(
            context=context["context"]
        )

    async def navigate(self, url, timeout=90, no_skip=False, **kwargs):
        await self.await_interventions_started()
        try:
            return await asyncio.wait_for(
                asyncio.ensure_future(self._navigate(url, **kwargs)), timeout=timeout
            )
        except asyncio.exceptions.TimeoutError as t:
            if no_skip:
                raise t
                return
            pytest.skip(
                f"{self.request.fspath.basename}: Timed out navigating to site after {timeout} seconds. Please try again later."
            )
        except webdriver.bidi.error.UnknownErrorException as e:
            if no_skip:
                raise e
                return
            s = str(e)
            if "Address rejected" in s:
                pytest.skip(
                    f"{self.request.fspath.basename}: Site not responding. Please try again later."
                )
                return
            elif "NS_ERROR_UNKNOWN_HOST" in s:
                pytest.skip(
                    f"{self.request.fspath.basename}: Site appears to be down. Please try again later."
                )
                return
            elif "NS_ERROR_REDIRECT_LOOP" in s:
                pytest.skip(
                    f"{self.request.fspath.basename}: Site is stuck in a redirect loop. Please try again later."
                )
                return
            raise e

    async def _navigate(self, url, wait="complete", await_console_message=None):
        if self.session.test_config.get("use_pbm") or self.session.test_config.get(
            "use_strict_etp"
        ):
            print("waiting for content blocker...")
            self.wait_for_content_blocker()
        if await_console_message is not None:
            console_message = await self.promise_console_message_listener(
                await_console_message
            )
        if wait == "load":
            page_load = await self.promise_readystate_listener("load", url=url)
        try:
            await self.session.bidi_session.browsing_context.navigate(
                context=(await self.top_context())["context"],
                url=url,
                wait=wait if wait != "load" else None,
            )
        except webdriver.bidi.error.UnknownErrorException as u:
            m = str(u)
            if (
                "NS_BINDING_ABORTED" not in m
                and "NS_ERROR_ABORT" not in m
                and "NS_ERROR_WONT_HANDLE_CONTENT" not in m
            ):
                raise u
        if wait == "load":
            await page_load
        if await_console_message is not None:
            await console_message

    async def promise_event_listener(self, events, check_fn=None, timeout=20):
        if type(events) is not list:
            events = [events]

        await self.session.bidi_session.session.subscribe(events=events)

        future = self.event_loop.create_future()

        listener_removers = []

        def remove_listeners():
            for listener_remover in listener_removers:
                try:
                    listener_remover()
                except Exception:
                    pass

        async def on_event(method, data):
            print("on_event", method, data)
            val = None
            if check_fn is not None:
                val = check_fn(method, data)
                if val is None:
                    return
            future.set_result(val)

        for event in events:
            r = self.session.bidi_session.add_event_listener(event, on_event)
            listener_removers.append(r)

        async def task():
            try:
                return await asyncio.wait_for(future, timeout=timeout)
            finally:
                remove_listeners()
                try:
                    await asyncio.wait_for(
                        self.session.bidi_session.session.unsubscribe(events=events),
                        timeout=4,
                    )
                except asyncio.exceptions.TimeoutError:
                    print("Unexpectedly timed out unsubscribing", events)
                    pass

        return asyncio.create_task(task())

    async def promise_navigation_begins(self, url=None, **kwargs):
        def check(method, data):
            if url is None:
                return data
            if "url" in data and url in data["url"]:
                return data

        return await self.promise_event_listener(
            "browsingContext.navigationStarted", check, **kwargs
        )

    async def promise_console_message_listener(self, msg, **kwargs):
        def check(method, data):
            if "text" in data:
                if msg in data["text"]:
                    return data
            if "args" in data and len(data["args"]):
                for arg in data["args"]:
                    if "value" in arg and msg in arg["value"]:
                        return data

        return await self.promise_event_listener("log.entryAdded", check, **kwargs)

    async def is_console_message(self, message):
        try:
            await (await self.promise_console_message_listener(message, timeout=2))
            return True
        except asyncio.exceptions.TimeoutError:
            return False

    async def promise_readystate_listener(self, state, url=None, **kwargs):
        event = f"browsingContext.{state}"

        def check(method, data):
            if url is None or url in data["url"]:
                return data

        return await self.promise_event_listener(event, check, **kwargs)

    async def promise_frame_listener(self, url, state="domContentLoaded", **kwargs):
        event = f"browsingContext.{state}"

        def check(method, data):
            if url is None or url in data["url"]:
                return Client.Context(self, data["context"])

        return await self.promise_event_listener(event, check, **kwargs)

    async def find_frame_context_by_url(self, url):
        def find_in(arr, url):
            for context in arr:
                if url in context["url"]:
                    return context
            for context in arr:
                found = find_in(context["children"], url)
                if found:
                    return found

        return find_in([await self.top_context()], url)

    class Context:
        def __init__(self, client, id):
            self.client = client
            self.target = ContextTarget(id)

        async def find_css(self, selector, all=False):
            all = "All" if all else ""
            return await self.client.session.bidi_session.script.evaluate(
                expression=f"document.querySelector{all}('{selector}')",
                target=self.target,
                await_promise=False,
            )

        def timed_js(self, timeout, poll, fn, is_displayed=False):
            return f"""() => new Promise((_good, _bad) => {{
                        {self.is_displayed_js()}
                        var _poll = {poll} * 1000;
                        var _time = {timeout} * 1000;
                        var _done = false;
                        var resolve = val => {{
                            if ({is_displayed}) {{
                                if (val.length) {{
                                    val = val.filter(v = is_displayed(v));
                                }} else {{
                                    val = is_displayed(val) && val;
                                }}
                                if (!val.length && !val.matches) {{
                                    return;
                                }}
                            }}
                            _done = true;
                            clearInterval(_int);
                            _good(val);
                        }};
                        var reject = str => {{
                            _done = true;
                            clearInterval(_int);
                            _bad(val);
                        }};
                        var _int = setInterval(() => {{
                            {fn};
                            if (!_done) {{
                                _time -= _poll;
                                if (_time <= 0) {{
                                    reject();
                                }}
                            }}
                        }}, poll);
                    }})"""

        def is_displayed_js(self):
            return """
                function is_displayed(e) {
                    const s = window.getComputedStyle(e),
                          v = s.visibility === "visible",
                          o = Math.abs(parseFloat(s.opacity));
                    return e.getClientRects().length > 0 && v && (isNaN(o) || o === 1.0);
                }
                """

        async def await_css(
            self,
            selector,
            all=False,
            timeout=10,
            poll=0.25,
            condition=False,
            is_displayed=False,
        ):
            all = "All" if all else ""
            condition = (
                f"var elem=arguments[0]; if ({condition})" if condition else False
            )
            return await self.client.session.bidi_session.script.evaluate(
                expression=self.timed_js(
                    timeout,
                    poll,
                    f"""
                    var ele = document.querySelector{all}('{selector}')";
                    if (ele && (!"length" in ele || ele.length > 0)) {{
                        '{condition}'
                        resolve(ele);
                    }}
                    """,
                ),
                target=self.target,
                await_promise=True,
            )

        async def await_text(self, text, **kwargs):
            xpath = f"//*[text()[contains(.,'{text}')]]"
            return await self.await_xpath(self, xpath, **kwargs)

        async def await_xpath(
            self, xpath, all=False, timeout=10, poll=0.25, is_displayed=False
        ):
            all = "true" if all else "false"
            return await self.client.session.bidi_session.script.evaluate(
                expression=self.timed_js(
                    timeout,
                    poll,
                    """
                    var ret = [];
                    var r, res = document.evaluate(`{xpath}`, document, null, 4);
                    while (r = res.iterateNext()) {
                        ret.push(r);
                    }
                    resolve({all} ? ret : ret[0]);
                    """,
                ),
                target=self.target,
                await_promise=True,
            )

    def wrap_script_args(self, args):
        if args is None:
            return args
        out = []
        for arg in args:
            if arg is None:
                out.append({"type": "undefined"})
                continue
            elif isinstance(arg, webdriver.client.WebElement):
                out.append({"sharedId": arg.id})
                continue
            t = type(arg)
            if t is int or t is float:
                out.append({"type": "number", "value": arg})
            elif t is bool:
                out.append({"type": "boolean", "value": arg})
            elif t is str:
                out.append({"type": "string", "value": arg})
            else:
                if "type" in arg:
                    out.push(arg)
                    continue
                raise ValueError(f"Unhandled argument type: {t}")
        return out

    class PreloadScript:
        def __init__(self, client, script, target):
            self.client = client
            self.script = script
            if type(target) is list:
                self.target = target[0]
            else:
                self.target = target

        def stop(self):
            return self.client.session.bidi_session.script.remove_preload_script(
                script=self.script
            )

        async def run(self, fn, *args, await_promise=False):
            val = await self.client.session.bidi_session.script.call_function(
                arguments=self.client.wrap_script_args(args),
                await_promise=await_promise,
                function_declaration=fn,
                target=self.target,
            )
            if val and "value" in val:
                return val["value"]
            return val

    async def make_preload_script(self, text, sandbox=None, args=None, context=None):
        if not context:
            context = (await self.top_context())["context"]
        target = ContextTarget(context, sandbox)
        if args is None:
            text = f"() => {{ {text} }}"
        script = await self.session.bidi_session.script.add_preload_script(
            function_declaration=text,
            arguments=self.wrap_script_args(args),
            sandbox=sandbox,
        )
        return Client.PreloadScript(self, script, target)

    async def disable_window_alert(self):
        return await self.make_preload_script("window.alert = () => {}")

    async def set_prompt_responses(self, responses, timeout=10):
        if type(responses) is not list:
            responses = [responses]
        if not hasattr(self, "prompts_preload_script"):
            self.prompts_preload_script = await self.make_preload_script(
                f"""
                    const responses = {responses};
                    window.wrappedJSObject.prompt = function() {{
                        return responses.shift();
                    }}
                """,
                "prompt_detector",
            )
        return self.prompts_preload_script

    async def await_alert(self, texts, timeout=10):
        if type(texts) is not list:
            texts = [texts]
        if not hasattr(self, "alert_preload_script"):
            self.alert_preload_script = await self.make_preload_script(
                """
                    window.__alerts = [];
                    window.wrappedJSObject.alert = function(text) {
                        window.__alerts.push(text);
                    }
                """,
                "alert_detector",
            )
        return self.alert_preload_script.run(
            """(timeout, ...msgs) => new Promise(done => {
                    const interval = 200;
                    let count = 0;
                    const to = setInterval(() => {
                        for (const a of window.__alerts || []) {
                            for (const msg of msgs) {
                                if (a.includes(msg)) {
                                    clearInterval(to);
                                    done(a);
                                    return;
                                }
                            }
                        }
                        count += interval;
                        if (timeout && timeout * 1000 < count) {
                            clearInterval(to);
                            done(false);
                        }
                    }, interval);
               })
            """,
            timeout,
            *texts,
            await_promise=True,
        )

    async def await_popup(self, url=None):
        if not hasattr(self, "popup_preload_script"):
            self.popup_preload_script = await self.make_preload_script(
                """
                    window.__popups = [];
                    window.wrappedJSObject.open = function(url) {
                        window.__popups.push(url);
                    }
                """,
                "popup_detector",
            )
        return self.popup_preload_script.run(
            """(url) => new Promise(done => {
                    const to = setInterval(() => {
                        if (url === undefined && window.__popups.length) {
                            clearInterval(to);
                            return done(window.__popups[0]);
                        }
                        const found = window.__popups.find(u => u.includes(url));
                        if (found !== undefined) {
                            clearInterval(to);
                            done(found);
                        }
                    }, 1000);
               })
            """,
            url,
            await_promise=True,
        )

    async def track_listener(self, type, selector):
        if not hasattr(self, "listener_preload_script"):
            self.listener_preload_script = await self.make_preload_script(
                """
                window.__listeners = {};
                var proto = EventTarget.wrappedJSObject.prototype;
                var def = Object.getOwnPropertyDescriptor(proto, "addEventListener");
                var old = def.value;
                def.value = function(type, fn, opts) {
                    if ("matches" in this) {
                        if (!window.__listeners[type]) {
                            window.__listeners[type] = new Set();
                        }
                        window.__listeners[type].add(this);
                    }
                    return old.call(this, type, fn, opts)
                };
                Object.defineProperty(proto, "addEventListener", def);
            """,
                "listener_detector",
            )
        return Client.ListenerTracker(self.listener_preload_script, type, selector)

    @contextlib.asynccontextmanager
    async def preload_script(self, text, *args):
        script = await self.make_preload_script(text, "preload", args=args)
        yield script
        await script.stop()

    def back(self):
        self.session.back()

    def switch_to_frame(self, frame=None):
        if not frame:
            return self.session.transport.send(
                "POST", "session/{session_id}/frame/parent".format(**vars(self.session))
            )

        return self.session.transport.send(
            "POST",
            "session/{session_id}/frame".format(**vars(self.session)),
            {"id": frame},
            encoder=webdriver.protocol.Encoder,
            decoder=webdriver.protocol.Decoder,
            session=self.session,
        )

    def switch_frame(self, frame):
        self.session.switch_frame(frame)

    async def load_page_and_wait_for_iframe(
        self, url, finder, loads=1, timeout=None, **kwargs
    ):
        while loads > 0:
            await self.navigate(url, **kwargs)
            frame = self.await_element(finder, timeout=timeout)
            loads -= 1
        self.switch_frame(frame)
        return frame

    def execute_script(self, script, *args):
        return self.session.execute_script(script, args=args)

    def execute_async_script(self, script, *args, **kwargs):
        return self.session.execute_async_script(script, args, **kwargs)

    def clear_all_cookies(self):
        self.session.transport.send(
            "DELETE", f"session/{self.session.session_id}/cookie"
        )

    def send_element_command(self, element, method, uri, body=None):
        url = f"element/{element.id}/{uri}"
        return self.session.send_session_command(method, url, body)

    def get_element_attribute(self, element, name):
        return self.send_element_command(element, "GET", f"attribute/{name}")

    def _do_is_displayed_check(self, ele, is_displayed):
        if ele is None:
            return None

        if type(ele) in [list, tuple]:
            return [x for x in ele if self._do_is_displayed_check(x, is_displayed)]

        if is_displayed is False and ele and self.is_displayed(ele):
            return None
        if is_displayed is True and ele and not self.is_displayed(ele):
            return None
        return ele

    def find_css(self, *args, all=False, is_displayed=None, **kwargs):
        try:
            ele = self.session.find.css(*args, all=all, **kwargs)
            return self._do_is_displayed_check(ele, is_displayed)
        except webdriver.error.NoSuchElementException:
            return None

    def find_xpath(self, xpath, all=False, is_displayed=None):
        route = "elements" if all else "element"
        body = {"using": "xpath", "value": xpath}
        try:
            ele = self.session.send_session_command("POST", route, body)
            return self._do_is_displayed_check(ele, is_displayed)
        except webdriver.error.NoSuchElementException:
            return None

    def find_text(self, text, is_displayed=None, **kwargs):
        try:
            e = self.find_xpath(f"//*[text()[contains(.,'{text}')]]", **kwargs)
            return self._do_is_displayed_check(e, is_displayed)
        except webdriver.error.NoSuchElementException:
            return None

    def find_element(self, finder, is_displayed=None, all=None, **kwargs):
        ele = finder.find(self, all=True, **kwargs)
        found = self._do_is_displayed_check(ele, is_displayed)
        if not all:
            return found[0] if len(found) else None
        return found

    def await_css(self, selector, **kwargs):
        return self.await_element(self.css(selector), **kwargs)

    def await_xpath(self, selector, **kwargs):
        return self.await_element(self.xpath(selector), **kwargs)

    def await_text(self, selector, *args, **kwargs):
        return self.await_element(self.text(selector), **kwargs)

    def await_element(self, finder, **kwargs):
        return self.await_first_element_of([finder], **kwargs)[0]

    class css:
        def __init__(self, selector):
            self.selector = selector

        def find(self, client, **kwargs):
            return client.find_css(self.selector, **kwargs)

    class xpath:
        def __init__(self, selector):
            self.selector = selector

        def find(self, client, **kwargs):
            return client.find_xpath(self.selector, **kwargs)

    class text:
        def __init__(self, selector):
            self.selector = selector

        def find(self, client, **kwargs):
            return client.find_text(self.selector, **kwargs)

    def await_first_element_of(
        self, finders, timeout=None, delay=0.25, condition=False, all=False, **kwargs
    ):
        t0 = time.time()
        condition = (
            f"return arguments[0].filter(elem => {condition})" if condition else False
        )

        if timeout is None:
            timeout = 10

        found = [None for finder in finders]

        exc = None
        while time.time() < t0 + timeout:
            for i, finder in enumerate(finders):
                try:
                    result = finder.find(self, all=True, **kwargs)
                    if len(result):
                        if condition:
                            result = self.session.execute_script(condition, [result])
                            if not len(result):
                                continue
                        found[i] = result[0] if not all else result
                        return found
                except webdriver.error.NoSuchElementException as e:
                    exc = e
            time.sleep(delay)
        raise exc if exc is not None else webdriver.error.NoSuchElementException
        return found

    async def dom_ready(self, timeout=None):
        if timeout is None:
            timeout = 20

        async def wait():
            return self.session.execute_async_script(
                """
                const cb = arguments[0];
                setInterval(() => {
                    if (document.readyState === "complete") {
                        cb();
                    }
                }, 500);
            """
            )

        task = asyncio.create_task(wait())
        return await asyncio.wait_for(task, timeout)

    def is_float_cleared(self, elem1, elem2):
        return self.session.execute_script(
            """return (function(a, b) {
            // Ensure that a is placed under b (and not to its right)
            return a?.offsetTop >= b?.offsetTop + b?.offsetHeight &&
                   a?.offsetLeft < b?.offsetLeft + b?.offsetWidth;
            }(arguments[0], arguments[1]));""",
            elem1,
            elem2,
        )

    def is_content_wider_than_screen(self):
        return self.execute_script("return window.innerWidth > window.outerWidth")

    @contextlib.contextmanager
    def assert_getUserMedia_called(self):
        self.execute_script(
            """
            navigator.mediaDevices.getUserMedia =
                navigator.mozGetUserMedia =
                navigator.getUserMedia =
                () => { window.__gumCalled = true; };
        """
        )
        yield
        assert self.execute_script("return window.__gumCalled === true;")

    def await_element_hidden(self, finder, timeout=None, delay=0.25):
        t0 = time.time()

        if timeout is None:
            timeout = 20

        elem = finder.find(self)
        while time.time() < t0 + timeout:
            try:
                if not self.is_displayed(elem):
                    return
                time.sleep(delay)
            except webdriver.error.StaleElementReferenceException:
                return

    def try_closing_popup(self, close_button_finder, timeout=None):
        try:
            self.soft_click(
                self.await_element(
                    close_button_finder, is_displayed=True, timeout=timeout
                )
            )
            self.await_element_hidden(close_button_finder)
            return True
        except webdriver.error.NoSuchElementException:
            return False

    def try_closing_popups(self, popup_close_button_finders, timeout=None):
        left_to_try = list(popup_close_button_finders)
        closed_one = False
        num_intercepted = 0
        while left_to_try:
            finder = left_to_try.pop(0)
            try:
                if self.try_closing_popup(finder, timeout=timeout):
                    closed_one = True
                    num_intercepted = 0
            except webdriver.error.ElementClickInterceptedException as e:
                # If more than one popup is visible at the same time, we will
                # get this exception for all but the topmost one. So we re-try
                # removing the others again after the topmost one is dismissed,
                # until we've removed them all.
                num_intercepted += 1
                if num_intercepted == len(left_to_try):
                    raise e
                left_to_try.append(finder)
        return closed_one

    def click(
        self, element, force=False, popups=None, popups_timeout=None, button=None
    ):
        tries = 0
        while True:
            self.scroll_into_view(element)
            try:
                if button:
                    self.mouse.pointer_move(0, 0, origin=element).pointer_down(
                        button
                    ).pointer_up(button).perform()
                else:
                    element.click()
                return
            except webdriver.error.ElementClickInterceptedException as c:
                if force:
                    self.clear_covering_elements(element)
                elif not popups or not self.try_closing_popups(
                    popups, timeout=popups_timeout
                ):
                    raise c
            except webdriver.error.WebDriverException as e:
                if not "could not be scrolled into view" in str(e):
                    raise e
                tries += 1
                if tries == 5:
                    raise e
                time.sleep(0.5)

    def soft_click(self, element, popups=None, popups_timeout=None):
        while True:
            try:
                self.execute_script("arguments[0].click()", element)
                return
            except webdriver.error.ElementClickInterceptedException as e:
                if not popups or not self.try_closing_popups(
                    popups, timeout=popups_timeout
                ):
                    raise e

    def remove_element(self, element):
        self.execute_script("arguments[0].remove()", element)

    def clear_covering_elements(self, element):
        self.execute_script(
            """
                const getInViewCentrePoint = function(rect, win) {
                  const { floor, max, min } = Math;
                  let visible = {
                    left: max(0, min(rect.x, rect.x + rect.width)),
                    right: min(win.innerWidth, max(rect.x, rect.x + rect.width)),
                    top: max(0, min(rect.y, rect.y + rect.height)),
                    bottom: min(win.innerHeight, max(rect.y, rect.y + rect.height)),
                  };
                  let x = (visible.left + visible.right) / 2.0;
                  let y = (visible.top + visible.bottom) / 2.0;
                  x = floor(x);
                  y = floor(y);
                  return { x, y };
                };

                const el = arguments[0];
                if (el.isConnected) {
                    const rect = el.getClientRects()[0];
                    if (rect) {
                        const c = getInViewCentrePoint(rect, window);
                        const efp = el.getRootNode().elementsFromPoint(c.x, c.y);
                        for (const cover of efp) {
                            if (cover == el) {
                                break;
                            }
                            cover.style.visibility = "hidden";
                        }
                    }
                }
            """,
            element,
        )

    def scroll_into_view(self, element):
        self.execute_script(
            "arguments[0].scrollIntoView({block:'center', inline:'center', behavior: 'instant'})",
            element,
        )

    @contextlib.asynccontextmanager
    async def ensure_fastclick_activates(self):
        fastclick_preload_script = await self.make_preload_script(
            """
                var _ = document.createElement("webcompat_test");
                _.style = "position:absolute;right:-1px;width:1px;height:1px";
                document.documentElement.appendChild(_);
            """,
            "fastclick_forcer",
        )
        yield
        fastclick_preload_script.stop()

    async def ensure_InstallTrigger_defined(self):
        return await self.make_preload_script("window.InstallTrigger = function() {}")

    async def ensure_InstallTrigger_undefined(self):
        return await self.make_preload_script("delete InstallTrigger")

    def test_future_plc_trending_scrollbar(self, shouldFail=False):
        trending_list = self.await_css(".trending__list")
        if not trending_list:
            raise ValueError("trending list is still where expected")

        # First confirm that the scrollbar is the color the site specifies.
        css_var_colors = self.execute_script(
            """
            // first, force a scrollbar, as the content on each site might
            // not always be wide enough to force a scrollbar to appear.
            const list = arguments[0];
            list.style.overflow = "scroll hidden !important";

            const computedStyle = getComputedStyle(list);
            return [
              computedStyle.getPropertyValue('--trending-scrollbar-color'),
              computedStyle.getPropertyValue('--trending-scrollbar-background-color'),
            ];
        """,
            trending_list,
        )
        if not css_var_colors[0] or not css_var_colors[1]:
            raise ValueError("expected CSS vars are still used for scrollbar-color")

        [expected, actual] = self.execute_script(
            """
            const [list, cssVarColors] = arguments;
            const sbColor = getComputedStyle(list).scrollbarColor;
            // scrollbar-color is a two-color value wth no easy way to separate
            // them and no way to be sure the value will remain consistent in
            // the format "rgb(x, y, z) rgb(x, y, z)". Likewise, the colors the
            // site specified in the CSS might be in hex format or any CSS color
            // value. So rather than trying to normalize the values ourselves, we
            // set the border-color of an element, which is also a two-color CSS
            // value, and then also read it back through the computed style, so
            // Firefox normalizes both colors the same way for us and lets us
            // compare their equivalence as simple strings.
            list.style.borderColor = sbColor;
            const actual = getComputedStyle(list).borderColor;
            list.style.borderColor = cssVarColors.join(" ");
            const expected = getComputedStyle(list).borderColor;
            return [expected, actual];
        """,
            trending_list,
            css_var_colors,
        )
        if shouldFail:
            assert expected != actual, "scrollbar is not the correct color"
        else:
            assert expected == actual, "scrollbar is the correct color"

        # Also check that the scrollbar does not cover any text (it may not
        # actually cover any text even without the intervention, so we skip
        # checking that case). To find out, we color the scrollbar the same as
        # the trending list's background, and compare screenshots of the
        # list with and without the scrollbar. This way if no text is covered,
        # the screenshots will not differ.
        if not shouldFail:
            self.execute_script(
                """
                const list = arguments[0];
                const bgc = getComputedStyle(list).backgroundColor;
                list.style.scrollbarColor = `${bgc} ${bgc}`;
            """,
                trending_list,
            )
            with_scrollbar = trending_list.screenshot()
            self.execute_script(
                """
                arguments[0].style.scrollbarWidth = "none";
            """,
                trending_list,
            )
            without_scrollbar = trending_list.screenshot()
            assert (
                with_scrollbar == without_scrollbar
            ), "scrollbar does not cover any text"

    def test_for_fastclick(self, element):
        # FastClick cancels touchend, breaking default actions on Fenix.
        # It instead fires a mousedown or click, which we can detect.
        self.execute_script(
            """
                const sel = arguments[0];
                window.fastclicked = false;
                const evt = sel.nodeName === "SELECT" ? "mousedown" : "click";
                document.addEventListener(evt, e => {
                    if (e.target === sel && !e.isTrusted) {
                        window.fastclicked = true;
                    }
                }, true);
                sel.style.position = "absolute";
                sel.style.zIndex = 2147483647;
            """,
            element,
        )
        self.scroll_into_view(element)
        self.clear_covering_elements(element)
        # tap a few times in case the site's other code interferes
        self.touch.click(element=element).perform()
        self.touch.click(element=element).perform()
        self.touch.click(element=element).perform()
        return self.execute_script("return window.fastclicked")

    def is_displayed(self, element):
        if element is None:
            return False

        try:
            return self.session.execute_script(
                """
                  const e = arguments[0],
                  s = window.getComputedStyle(e),
                  v = s.visibility === "visible",
                  o = Math.abs(parseFloat(s.opacity));
                  return e.getClientRects().length > 0 && v && (isNaN(o) || o === 1.0);
              """,
                args=[element],
            )
        except webdriver.error.StaleElementReferenceException:
            return False

    def is_one_solid_color(self, element, max_fuzz=8):
        # max_fuzz is needed as screenshots can have slight color bleeding/fringing
        shotb64 = element.screenshot()
        shot = Image.open(BytesIO(b64decode(shotb64))).convert("RGB")
        for min, max in shot.getextrema():
            if max - min > max_fuzz:
                return False
        return True