ladybird/Userland/Services/WebDriver/Session.cpp

/*
 * Copyright (c) 2022, Florent Castelli <florent.castelli@gmail.com>
 * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
 * Copyright (c) 2022, Tobias Christiansen <tobyase@serenityos.org>
 * Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
 * Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "Session.h"
#include "BrowserConnection.h"
#include "Client.h"
#include <AK/Base64.h>
#include <AK/NumericLimits.h>
#include <AK/Time.h>
#include <AK/URL.h>
#include <LibCore/LocalServer.h>
#include <LibCore/Stream.h>
#include <LibCore/System.h>
#include <LibGfx/PNGWriter.h>
#include <LibGfx/Point.h>
#include <LibGfx/Rect.h>
#include <LibGfx/Size.h>
#include <LibWeb/Cookie/Cookie.h>
#include <LibWeb/Cookie/ParsedCookie.h>
#include <LibWeb/WebDriver/ExecuteScript.h>
#include <unistd.h>

namespace WebDriver {

Session::Session(unsigned session_id, NonnullRefPtr<Client> client)
    : m_client(move(client))
    , m_id(session_id)
{
}

Session::~Session()
{
    if (m_started) {
        auto error = stop();
        if (error.is_error()) {
            warnln("Failed to stop session {}: {}", m_id, error.error());
        }
    }
}

ErrorOr<Session::Window*, Web::WebDriver::Error> Session::current_window()
{
    auto window = m_windows.get(m_current_window_handle);
    if (!window.has_value())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchWindow, "Window not found");
    return window.release_value();
}

ErrorOr<void, Web::WebDriver::Error> Session::check_for_open_top_level_browsing_context_or_return_error()
{
    (void)TRY(current_window());
    return {};
}

ErrorOr<NonnullRefPtr<Core::LocalServer>> Session::create_server(String const& socket_path, ServerType type, NonnullRefPtr<ServerPromise> promise)
{
    dbgln("Listening for WebDriver connection on {}", socket_path);

    auto server = TRY(Core::LocalServer::try_create());
    server->listen(socket_path);

    server->on_accept = [this, type, promise](auto client_socket) mutable {
        switch (type) {
        case ServerType::Browser: {
            auto maybe_connection = adopt_nonnull_ref_or_enomem(new (nothrow) BrowserConnection(move(client_socket), m_client, session_id()));
            if (maybe_connection.is_error()) {
                promise->resolve(maybe_connection.release_error());
                return;
            }

            dbgln("WebDriver is connected to Browser socket");
            m_browser_connection = maybe_connection.release_value();
            break;
        }

        case ServerType::WebContent: {
            auto maybe_connection = adopt_nonnull_ref_or_enomem(new (nothrow) WebContentConnection(move(client_socket), m_client, session_id()));
            if (maybe_connection.is_error()) {
                promise->resolve(maybe_connection.release_error());
                return;
            }

            dbgln("WebDriver is connected to WebContent socket");
            m_web_content_connection = maybe_connection.release_value();
            break;
        }
        }

        if (m_browser_connection && m_web_content_connection)
            promise->resolve({});
    };

    server->on_accept_error = [promise](auto error) mutable {
        promise->resolve(move(error));
    };

    return server;
}

ErrorOr<void> Session::start()
{
    auto promise = TRY(ServerPromise::try_create());

    auto browser_socket_path = String::formatted("/tmp/webdriver/browser_{}_{}", getpid(), m_id);
    auto browser_server = TRY(create_server(browser_socket_path, ServerType::Browser, promise));

    auto web_content_socket_path = String::formatted("/tmp/webdriver/content_{}_{}", getpid(), m_id);
    auto web_content_server = TRY(create_server(web_content_socket_path, ServerType::WebContent, promise));

    char const* argv[] = {
        "/bin/Browser",
        "--webdriver-browser-path",
        browser_socket_path.characters(),
        "--webdriver-content-path",
        web_content_socket_path.characters(),
        nullptr,
    };

    TRY(Core::System::posix_spawn("/bin/Browser"sv, nullptr, nullptr, const_cast<char**>(argv), environ));

    // FIXME: Allow this to be more asynchronous. For now, this at least allows us to propagate
    //        errors received while accepting the Browser and WebContent sockets.
    TRY(promise->await());

    m_started = true;
    m_windows.set("main", make<Session::Window>("main", true));
    m_current_window_handle = "main";

    return {};
}

// https://w3c.github.io/webdriver/#dfn-close-the-session
Web::WebDriver::Response Session::stop()
{
    // 1. Perform the following substeps based on the remote end’s type:
    // NOTE: We perform the "Remote end is an endpoint node" steps in the WebContent process.
    m_web_content_connection->close_session();
    m_web_content_connection = nullptr;

    // 2. Remove the current session from active sessions.
    // NOTE: Handled by WebDriver::Client.

    // 3. Perform any implementation-specific cleanup steps.
    m_browser_connection->async_quit();
    m_started = false;

    // 4. If an error has occurred in any of the steps above, return the error, otherwise return success with data null.
    return JsonValue {};
}

// 9.1 Get Timeouts, https://w3c.github.io/webdriver/#dfn-get-timeouts
JsonObject Session::get_timeouts()
{
    // 1. Let timeouts be the timeouts object for session’s timeouts configuration
    auto timeouts = timeouts_object(m_timeouts_configuration);

    // 2. Return success with data timeouts.
    return timeouts;
}

// 9.2 Set Timeouts, https://w3c.github.io/webdriver/#dfn-set-timeouts
Web::WebDriver::Response Session::set_timeouts(JsonValue const& payload)
{
    // 1. Let timeouts be the result of trying to JSON deserialize as a timeouts configuration the request’s parameters.
    auto timeouts = TRY(json_deserialize_as_a_timeouts_configuration(payload));

    // 2. Make the session timeouts the new timeouts.
    m_timeouts_configuration = move(timeouts);

    // 3. Return success with data null.
    return JsonValue {};
}

// 10.3 Back, https://w3c.github.io/webdriver/#dfn-back
Web::WebDriver::Response Session::back()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Traverse the history by a delta –1 for the current browsing context.
    m_browser_connection->async_back();

    // FIXME: 4. If the previous step completed results in a pageHide event firing, wait until pageShow event
    //           fires or for the session page load timeout milliseconds to pass, whichever occurs sooner.

    // FIXME: 5. If the previous step completed by the session page load timeout being reached, and user
    //           prompts have been handled, return error with error code timeout.

    // 6. Return success with data null.
    return JsonValue();
}

// 10.4 Forward, https://w3c.github.io/webdriver/#dfn-forward
Web::WebDriver::Response Session::forward()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Traverse the history by a delta 1 for the current browsing context.
    m_browser_connection->async_forward();

    // FIXME: 4. If the previous step completed results in a pageHide event firing, wait until pageShow event
    //           fires or for the session page load timeout milliseconds to pass, whichever occurs sooner.

    // FIXME: 5. If the previous step completed by the session page load timeout being reached, and user
    //           prompts have been handled, return error with error code timeout.

    // 6. Return success with data null.
    return JsonValue();
}

// 10.5 Refresh, https://w3c.github.io/webdriver/#dfn-refresh
Web::WebDriver::Response Session::refresh()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Initiate an overridden reload of the current top-level browsing context’s active document.
    m_browser_connection->async_refresh();

    // FIXME: 4. If url is special except for file:

    // FIXME:     1. Try to wait for navigation to complete.

    // FIXME:     2. Try to run the post-navigation checks.

    // FIXME: 5. Set the current browsing context with current top-level browsing context.

    // 6. Return success with data null.
    return JsonValue();
}

// 10.6 Get Title, https://w3c.github.io/webdriver/#dfn-get-title
Web::WebDriver::Response Session::get_title()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let title be the initial value of the title IDL attribute of the current top-level browsing context's active document.
    // 4. Return success with data title.
    return JsonValue(m_browser_connection->get_title());
}

// 11.1 Get Window Handle, https://w3c.github.io/webdriver/#get-window-handle
Web::WebDriver::Response Session::get_window_handle()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // 2. Return success with data being the window handle associated with the current top-level browsing context.
    return JsonValue { m_current_window_handle };
}

// 11.2 Close Window, https://w3c.github.io/webdriver/#dfn-close-window
ErrorOr<void, Variant<Web::WebDriver::Error, Error>> Session::close_window()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // 2. Close the current top-level browsing context.
    m_windows.remove(m_current_window_handle);

    // 3. If there are no more open top-level browsing contexts, then close the session.
    if (m_windows.is_empty()) {
        auto result = stop();
        if (result.is_error()) {
            return Variant<Web::WebDriver::Error, Error>(result.release_error());
        }
    }

    return {};
}

// 11.4 Get Window Handles, https://w3c.github.io/webdriver/#dfn-get-window-handles
Web::WebDriver::Response Session::get_window_handles() const
{
    // 1. Let handles be a JSON List.
    auto handles = JsonArray {};

    // 2. For each top-level browsing context in the remote end, push the associated window handle onto handles.
    for (auto const& window_handle : m_windows.keys())
        handles.append(window_handle);

    // 3. Return success with data handles.
    return JsonValue { handles };
}

static JsonValue serialize_rect(Gfx::IntRect const& rect)
{
    JsonObject serialized_rect = {};
    serialized_rect.set("x", rect.x());
    serialized_rect.set("y", rect.y());
    serialized_rect.set("width", rect.width());
    serialized_rect.set("height", rect.height());

    return serialized_rect;
}

// https://w3c.github.io/webdriver/#dfn-get-a-known-connected-element
static ErrorOr<i32, Web::WebDriver::Error> get_known_connected_element(StringView element_id)
{
    // NOTE: The whole concept of "connected elements" is not implemented yet. See get_or_create_a_web_element_reference().
    //       For now the element is only represented by its ID.
    auto maybe_element_id = element_id.to_int();
    if (!maybe_element_id.has_value())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Element ID is not an integer");

    return maybe_element_id.release_value();
}

// 12.4.6 Get Element Tag Name, https://w3c.github.io/webdriver/#dfn-get-element-tag-name
Web::WebDriver::Response Session::get_element_tag_name(JsonValue const&, StringView parameter_element_id)
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let element be the result of trying to get a known connected element with url variable element id.
    auto element_id = TRY(get_known_connected_element(parameter_element_id));

    // 4. Let qualified name be the result of getting element’s tagName IDL attribute.
    auto qualified_name = m_browser_connection->get_element_tag_name(element_id);

    // 5. Return success with data qualified name.
    return JsonValue(qualified_name);
}

// 12.4.7 Get Element Rect, https://w3c.github.io/webdriver/#dfn-get-element-rect
Web::WebDriver::Response Session::get_element_rect(StringView parameter_element_id)
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let element be the result of trying to get a known connected element with url variable element id.
    auto element_id = TRY(get_known_connected_element(parameter_element_id));

    // 4. Calculate the absolute position of element and let it be coordinates.
    // 5. Let rect be element’s bounding rectangle.
    auto rect = m_browser_connection->get_element_rect(element_id);

    // 6. Let body be a new JSON Object initialized with:
    // "x"
    //     The first value of coordinates.
    // "y"
    //     The second value of coordinates.
    // "width"
    //     Value of rect’s width dimension.
    // "height"
    //     Value of rect’s height dimension.
    auto body = serialize_rect(rect);

    // 7. Return success with data body.
    return body;
}

// 12.4.8 Is Element Enabled, https://w3c.github.io/webdriver/#dfn-is-element-enabled
Web::WebDriver::Response Session::is_element_enabled(StringView parameter_element_id)
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let element be the result of trying to get a known connected element with url variable element id.
    auto element_id = TRY(get_known_connected_element(parameter_element_id));

    // 4. Let enabled be a boolean initially set to true if the current browsing context’s active document’s type is not "xml".
    // 5. Otherwise, let enabled to false and jump to the last step of this algorithm.
    // 6. Set enabled to false if a form control is disabled.
    auto enabled = m_browser_connection->is_element_enabled(element_id);

    // 7. Return success with data enabled.
    return JsonValue { enabled };
}

// 13.1 Get Page Source, https://w3c.github.io/webdriver/#dfn-get-page-source
Web::WebDriver::Response Session::get_source()
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let source be the result of invoking the fragment serializing algorithm on a fictional node whose only child is the document element providing true for the require well-formed flag. If this causes an exception to be thrown, let source be null.
    // 4. Let source be the result of serializing to string the current browsing context active document, if source is null.
    // NOTE: Both of the above cases are handled in the remote WebContent process.
    auto source = m_browser_connection->serialize_source();

    // 5. Return success with data source.
    return JsonValue { source };
}

struct ScriptArguments {
    String script;
    JsonArray const& arguments;
};

// https://w3c.github.io/webdriver/#dfn-extract-the-script-arguments-from-a-request
static ErrorOr<ScriptArguments, Web::WebDriver::Error> extract_the_script_arguments_from_a_request(JsonValue const& payload)
{
    if (!payload.is_object())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Payload is not a JSON object");

    auto const& properties = payload.as_object();

    // 1. Let script be the result of getting a property named script from the parameters.
    // 2. If script is not a String, return error with error code invalid argument.
    if (!properties.has_string("script"sv))
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Payload doesn't have a 'script' string property");
    auto script = properties.get("script"sv).as_string();

    // 3. Let args be the result of getting a property named args from the parameters.
    // 4. If args is not an Array return error with error code invalid argument.
    if (!properties.has_array("args"sv))
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Payload doesn't have an 'args' string property");
    auto const& args = properties.get("args"sv).as_array();

    // 5. Let arguments be the result of calling the JSON deserialize algorithm with arguments args.
    // NOTE: We forward the JSON array to the Browser and then WebContent process over IPC, so this is not necessary.

    // 6. Return success with data script and arguments.
    return ScriptArguments { script, args };
}

// 13.2.1 Execute Script, https://w3c.github.io/webdriver/#dfn-execute-script
Web::WebDriver::Response Session::execute_script(JsonValue const& payload)
{
    // 1. Let body and arguments be the result of trying to extract the script arguments from a request with argument parameters.
    auto const& [body, arguments] = TRY(extract_the_script_arguments_from_a_request(payload));

    // 2. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 3. Handle any user prompts, and return its value if it is an error.

    // 4., 5.1-5.3.
    Vector<String> json_arguments;
    arguments.for_each([&](JsonValue const& json_value) {
        // NOTE: serialized() instead of to_string() ensures proper quoting.
        json_arguments.append(json_value.serialized<StringBuilder>());
    });

    dbgln("Executing script with 'args': [{}] / 'body':\n{}", String::join(", "sv, json_arguments), body);
    auto execute_script_response = m_browser_connection->execute_script(body, json_arguments, m_timeouts_configuration.script_timeout, false);
    dbgln("Executing script returned: {}", execute_script_response.json_result());

    // NOTE: This is assumed to be a valid JSON value.
    auto result = MUST(JsonValue::from_string(execute_script_response.json_result()));

    switch (execute_script_response.result_type()) {
    // 6. If promise is still pending and the session script timeout is reached, return error with error code script timeout.
    case Web::WebDriver::ExecuteScriptResultType::Timeout:
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::ScriptTimeoutError, "Script timed out");
    // 7. Upon fulfillment of promise with value v, let result be a JSON clone of v, and return success with data result.
    case Web::WebDriver::ExecuteScriptResultType::PromiseResolved:
        return result;
    // 8. Upon rejection of promise with reason r, let result be a JSON clone of r, and return error with error code javascript error and data result.
    case Web::WebDriver::ExecuteScriptResultType::PromiseRejected:
    case Web::WebDriver::ExecuteScriptResultType::JavaScriptError:
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::JavascriptError, "Script returned an error", move(result));
    default:
        VERIFY_NOT_REACHED();
    }
}

// 13.2.2 Execute Async Script, https://w3c.github.io/webdriver/#dfn-execute-async-script
Web::WebDriver::Response Session::execute_async_script(JsonValue const& parameters)
{
    // 1. Let body and arguments by the result of trying to extract the script arguments from a request with argument parameters.
    auto [body, arguments] = TRY(extract_the_script_arguments_from_a_request(parameters));

    // 2. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 3. Handle any user prompts, and return its value if it is an error.

    // 4., 5.1-5.11.
    Vector<String> json_arguments;
    arguments.for_each([&](JsonValue const& json_value) {
        // NOTE: serialized() instead of to_string() ensures proper quoting.
        json_arguments.append(json_value.serialized<StringBuilder>());
    });

    dbgln("Executing async script with 'args': [{}] / 'body':\n{}", String::join(", "sv, json_arguments), body);
    auto execute_script_response = m_browser_connection->execute_script(body, json_arguments, m_timeouts_configuration.script_timeout, true);
    dbgln("Executing async script returned: {}", execute_script_response.json_result());

    // NOTE: This is assumed to be a valid JSON value.
    auto result = MUST(JsonValue::from_string(execute_script_response.json_result()));

    switch (execute_script_response.result_type()) {
    // 6. If promise is still pending and the session script timeout is reached, return error with error code script timeout.
    case Web::WebDriver::ExecuteScriptResultType::Timeout:
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::ScriptTimeoutError, "Script timed out");
    // 7. Upon fulfillment of promise with value v, let result be a JSON clone of v, and return success with data result.
    case Web::WebDriver::ExecuteScriptResultType::PromiseResolved:
        return result;
    // 8. Upon rejection of promise with reason r, let result be a JSON clone of r, and return error with error code javascript error and data result.
    case Web::WebDriver::ExecuteScriptResultType::PromiseRejected:
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::JavascriptError, "Script returned an error", move(result));
    default:
        VERIFY_NOT_REACHED();
    }
}

// https://w3c.github.io/webdriver/#dfn-serialized-cookie
static JsonObject serialize_cookie(Web::Cookie::Cookie const& cookie)
{
    JsonObject serialized_cookie = {};
    serialized_cookie.set("name", cookie.name);
    serialized_cookie.set("value", cookie.value);
    serialized_cookie.set("path", cookie.path);
    serialized_cookie.set("domain", cookie.domain);
    serialized_cookie.set("secure", cookie.secure);
    serialized_cookie.set("httpOnly", cookie.http_only);
    serialized_cookie.set("expiry", cookie.expiry_time.timestamp());
    // FIXME: Add sameSite to Cookie and serialize it here too.

    return serialized_cookie;
}

// 14.1 Get All Cookies, https://w3c.github.io/webdriver/#dfn-get-all-cookies
Web::WebDriver::Response Session::get_all_cookies()
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts, and return its value if it is an error.

    // 3. Let cookies be a new JSON List.
    JsonArray cookies = {};

    // 4. For each cookie in all associated cookies of the current browsing context’s active document:
    for (auto const& cookie : m_browser_connection->get_all_cookies()) {
        // 1. Let serialized cookie be the result of serializing cookie.
        auto serialized_cookie = serialize_cookie(cookie);

        // 2. Append serialized cookie to cookies
        cookies.append(serialized_cookie);
    }

    // 5. Return success with data cookies.
    return JsonValue(cookies);
}

// 14.2 Get Named Cookie, https://w3c.github.io/webdriver/#dfn-get-named-cookie
Web::WebDriver::Response Session::get_named_cookie(String const& name)
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts, and return its value if it is an error.

    // 3. If the url variable name is equal to a cookie’s cookie name amongst all associated cookies of the
    //    current browsing context’s active document, return success with the serialized cookie as data.
    auto maybe_cookie = m_browser_connection->get_named_cookie(name);
    if (maybe_cookie.has_value()) {
        auto cookie = maybe_cookie.release_value();
        auto serialized_cookie = serialize_cookie(cookie);
        return JsonValue(serialized_cookie);
    }

    // 4. Otherwise, return error with error code no such cookie.
    return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchCookie, "Cookie not found");
}

// 14.3 Add Cookie, https://w3c.github.io/webdriver/#dfn-adding-a-cookie
Web::WebDriver::Response Session::add_cookie(JsonValue const& payload)
{
    // 1. Let data be the result of getting a property named cookie from the parameters argument.
    if (!payload.is_object() || !payload.as_object().has_object("cookie"sv))
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Payload doesn't have a cookie object");

    auto const& maybe_data = payload.as_object().get("cookie"sv);

    // 2. If data is not a JSON Object with all the required (non-optional) JSON keys listed in the table for cookie conversion,
    //    return error with error code invalid argument.
    // NOTE: Table is here: https://w3c.github.io/webdriver/#dfn-table-for-cookie-conversion
    if (!maybe_data.is_object())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Value \"cookie\' is not an object");

    auto const& data = maybe_data.as_object();

    if (!data.has("name"sv) || !data.has("value"sv))
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Cookie-Object doesn't contain all required keys");

    // 3. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 4. Handle any user prompts, and return its value if it is an error.

    // FIXME: 5. If the current browsing context’s document element is a cookie-averse Document object,
    //           return error with error code invalid cookie domain.

    // 6. If cookie name or cookie value is null,
    //    FIXME: cookie domain is not equal to the current browsing context’s active document’s domain,
    //    cookie secure only or cookie HTTP only are not boolean types,
    //    or cookie expiry time is not an integer type, or it less than 0 or greater than the maximum safe integer,
    //    return error with error code invalid argument.
    if (data.get("name"sv).is_null() || data.get("value"sv).is_null())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Cookie-Object is malformed: name or value are null");
    if (data.has("secure"sv) && !data.get("secure"sv).is_bool())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Cookie-Object is malformed: secure is not bool");
    if (data.has("httpOnly"sv) && !data.get("httpOnly"sv).is_bool())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Cookie-Object is malformed: httpOnly is not bool");
    Optional<Core::DateTime> expiry_time;
    if (data.has("expiry"sv)) {
        auto expiry_argument = data.get("expiry"sv);
        if (!expiry_argument.is_u32()) {
            // NOTE: less than 0 or greater than safe integer are handled by the JSON parser
            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Cookie-Object is malformed: expiry is not u32");
        }
        expiry_time = Core::DateTime::from_timestamp(expiry_argument.as_u32());
    }

    // 7. Create a cookie in the cookie store associated with the active document’s address using
    //    cookie name name, cookie value value, and an attribute-value list of the following cookie concepts
    //    listed in the table for cookie conversion from data:
    Web::Cookie::ParsedCookie cookie;
    if (auto name_attribute = data.get("name"sv); name_attribute.is_string())
        cookie.name = name_attribute.as_string();
    else
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Expect name attribute to be string");

    if (auto value_attribute = data.get("value"sv); value_attribute.is_string())
        cookie.value = value_attribute.as_string();
    else
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Expect value attribute to be string");

    // Cookie path
    //     The value if the entry exists, otherwise "/".
    if (data.has("path"sv)) {
        if (auto path_attribute = data.get("path"sv); path_attribute.is_string())
            cookie.path = path_attribute.as_string();
        else
            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Expect path attribute to be string");
    } else {
        cookie.path = "/";
    }

    // Cookie domain
    //     The value if the entry exists, otherwise the current browsing context’s active document’s URL domain.
    // NOTE: The otherwise case is handled by the CookieJar
    if (data.has("domain"sv)) {
        if (auto domain_attribute = data.get("domain"sv); domain_attribute.is_string())
            cookie.domain = domain_attribute.as_string();
        else
            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Expect domain attribute to be string");
    }

    // Cookie secure only
    //     The value if the entry exists, otherwise false.
    if (data.has("secure"sv)) {
        cookie.secure_attribute_present = data.get("secure"sv).as_bool();
    } else {
        cookie.secure_attribute_present = false;
    }

    // Cookie HTTP only
    //     The value if the entry exists, otherwise false.
    if (data.has("httpOnly"sv)) {
        cookie.http_only_attribute_present = data.get("httpOnly"sv).as_bool();
    } else {
        cookie.http_only_attribute_present = false;
    }

    // Cookie expiry time
    //     The value if the entry exists, otherwise leave unset to indicate that this is a session cookie.
    cookie.expiry_time_from_expires_attribute = expiry_time;

    // FIXME: Cookie same site
    //            The value if the entry exists, otherwise leave unset to indicate that no same site policy is defined.

    m_browser_connection->async_add_cookie(move(cookie));

    // If there is an error during this step, return error with error code unable to set cookie.
    // NOTE: This probably should only apply to the actual setting of the cookie in the Browser,
    //       which cannot fail in our case.
    //       Thus, the error-codes used above are 400 "invalid argument".

    // 8. Return success with data null.
    return JsonValue();
}

// https://w3c.github.io/webdriver/#dfn-delete-cookies
void Session::delete_cookies(Optional<StringView> const& name)
{
    // For each cookie among all associated cookies of the current browsing context’s active document,
    // run the substeps of the first matching condition:
    for (auto& cookie : m_browser_connection->get_all_cookies()) {
        // -> name is undefined
        // -> name is equal to cookie name
        if (!name.has_value() || name.value() == cookie.name) {
            // Set the cookie expiry time to a Unix timestamp in the past.
            cookie.expiry_time = Core::DateTime::from_timestamp(0);
            m_browser_connection->async_update_cookie(cookie);
        }
        // -> Otherwise
        //    Do nothing.
    }
}

// 14.4 Delete Cookie, https://w3c.github.io/webdriver/#dfn-delete-cookie
Web::WebDriver::Response Session::delete_cookie(StringView name)
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts, and return its value if it is an error.

    // 3. Delete cookies using the url variable name parameter as the filter argument.
    delete_cookies(name);

    // 4. Return success with data null.
    return JsonValue();
}

// 14.5 Delete All Cookies, https://w3c.github.io/webdriver/#dfn-delete-all-cookies
Web::WebDriver::Response Session::delete_all_cookies()
{
    // 1. If the current browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts, and return its value if it is an error.

    // 3. Delete cookies, giving no filtering argument.
    delete_cookies();

    // 4. Return success with data null.
    return JsonValue();
}

// https://w3c.github.io/webdriver/#dfn-encoding-a-canvas-as-base64
static ErrorOr<String, Web::WebDriver::Error> encode_bitmap_as_canvas_element(Gfx::Bitmap const& bitmap)
{
    // FIXME: 1. If the canvas element’s bitmap’s origin-clean flag is set to false, return error with error code unable to capture screen.

    // 2. If the canvas element’s bitmap has no pixels (i.e. either its horizontal dimension or vertical dimension is zero) then return error with error code unable to capture screen.
    if (bitmap.width() == 0 || bitmap.height() == 0)
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::UnableToCaptureScreen, "Captured screenshot is empty"sv);

    // 3. Let file be a serialization of the canvas element’s bitmap as a file, using "image/png" as an argument.
    auto file = Gfx::PNGWriter::encode(bitmap);

    // 4. Let data url be a data: URL representing file. [RFC2397]
    auto data_url = AK::URL::create_with_data("image/png"sv, encode_base64(file), true).to_string();

    // 5. Let index be the index of "," in data url.
    auto index = data_url.find(',');
    VERIFY(index.has_value());

    // 6. Let encoded string be a substring of data url using (index + 1) as the start argument.
    auto encoded_string = data_url.substring(*index + 1);

    // 7. Return success with data encoded string.
    return encoded_string;
}

// 17.1 Take Screenshot, https://w3c.github.io/webdriver/#take-screenshot
Web::WebDriver::Response Session::take_screenshot()
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // 2. When the user agent is next to run the animation frame callbacks:
    //     a. Let root rect be the current top-level browsing context’s document element’s rectangle.
    //     b. Let screenshot result be the result of trying to call draw a bounding box from the framebuffer, given root rect as an argument.
    auto screenshot = m_browser_connection->take_screenshot();
    if (!screenshot.is_valid())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::UnableToCaptureScreen, "Unable to capture screenshot"sv);

    //     c. Let canvas be a canvas element of screenshot result’s data.
    //     d. Let encoding result be the result of trying encoding a canvas as Base64 canvas.
    //     e. Let encoded string be encoding result’s data.
    auto encoded_string = TRY(encode_bitmap_as_canvas_element(*screenshot.bitmap()));

    // 3. Return success with data encoded string.
    return JsonValue { encoded_string };
}

// 17.2 Take Element Screenshot, https://w3c.github.io/webdriver/#dfn-take-element-screenshot
Web::WebDriver::Response Session::take_element_screenshot(StringView parameter_element_id)
{
    // 1. If the current top-level browsing context is no longer open, return error with error code no such window.
    TRY(check_for_open_top_level_browsing_context_or_return_error());

    // FIXME: 2. Handle any user prompts and return its value if it is an error.

    // 3. Let element be the result of trying to get a known connected element with url variable element id.
    auto element_id = TRY(get_known_connected_element(parameter_element_id));

    // 4. Scroll into view the element.
    m_browser_connection->scroll_element_into_view(element_id);

    // 5. When the user agent is next to run the animation frame callbacks:
    //     a. Let element rect be element’s rectangle.
    //     b. Let screenshot result be the result of trying to call draw a bounding box from the framebuffer, given element rect as an argument.
    auto screenshot = m_browser_connection->take_element_screenshot(element_id);
    if (!screenshot.is_valid())
        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::UnableToCaptureScreen, "Unable to capture screenshot"sv);

    //     c. Let canvas be a canvas element of screenshot result’s data.
    //     d. Let encoding result be the result of trying encoding a canvas as Base64 canvas.
    //     e. Let encoded string be encoding result’s data.
    auto encoded_string = TRY(encode_bitmap_as_canvas_element(*screenshot.bitmap()));

    // 6. Return success with data encoded string.
    return JsonValue { encoded_string };
}

}