/*
 * Copyright (c) 2023, Andrew Kaster <akaster@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibWeb/Bindings/PrincipalHostDefined.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOM/Event.h>
#include <LibWeb/DOM/EventTarget.h>
#include <LibWeb/HTML/ErrorEvent.h>
#include <LibWeb/HTML/EventLoop/EventLoop.h>
#include <LibWeb/HTML/EventNames.h>
#include <LibWeb/HTML/MessagePort.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/HTML/Scripting/ExceptionReporter.h>
#include <LibWeb/HTML/Window.h>
#include <LibWeb/HTML/Worker.h>
#include <LibWeb/HTML/WorkerAgentParent.h>
#include <LibWeb/Page/Page.h>
#include <LibWeb/Worker/WebWorkerClient.h>

namespace Web::HTML {

GC_DEFINE_ALLOCATOR(WorkerAgentParent);

WorkerAgentParent::WorkerAgentParent(URL::URL url, Bindings::WorkerOptions const& options, GC::Ptr<MessagePort> outside_port, GC::Ref<EnvironmentSettingsObject> outside_settings, GC::Ref<DOM::EventTarget> worker_event_target, Bindings::AgentType agent_type)
    : m_worker_options(options)
    , m_agent_type(agent_type)
    , m_url(move(url))
    , m_outside_port(outside_port)
    , m_outside_settings(outside_settings)
    , m_worker_event_target(worker_event_target)
{
}

void WorkerAgentParent::initialize(JS::Realm& realm)
{
    Base::initialize(realm);

    m_outside_settings->keep_worker_agent_alive_while_starting(*this);

    m_message_port = MessagePort::create(realm);
    m_message_port->entangle_with(*m_outside_port);

    TransferDataEncoder data_holder;
    MUST(m_message_port->transfer_steps(data_holder));

    // FIXME: Specification says this supposed to happen in step 11 of onComplete handler defined in https://html.spec.whatwg.org/multipage/workers.html#run-a-worker
    //        but that would require introducing a new IPC message type to communicate this from WebWorker to WebContent process,
    //        so let's do it here for now.
    m_outside_port->start();

    // NOTE: This blocking IPC call may launch another process.
    //    If spinning the event loop for this can cause other javascript to execute, we're in trouble.
    auto response = Bindings::principal_host_defined_page(realm).client().request_worker_agent(m_agent_type);

    auto transport = MUST(response.worker_handle.create_transport());
    m_worker_ipc = make_ref_counted<WebWorkerClient>(move(transport));
    setup_worker_ipc_callbacks(realm);

    m_worker_ipc->async_connect_to_request_server(move(response.request_server_handle));
    m_worker_ipc->async_connect_to_image_decoder(move(response.image_decoder_handle));

    auto serialized_outside_settings = m_outside_settings->serialize();

    m_worker_ipc->async_start_worker(m_url, m_worker_options.type, m_worker_options.credentials, m_worker_options.name, move(data_holder), serialized_outside_settings, m_agent_type);
}

void WorkerAgentParent::setup_worker_ipc_callbacks(JS::Realm& realm)
{
    // NOTE: As long as WorkerAgentParent is alive, realm and m_worker_ipc will be alive.
    m_worker_ipc->on_request_cookie = [realm = GC::RawRef { realm }](URL::URL const& url, HTTP::Cookie::Source source) {
        auto& client = Bindings::principal_host_defined_page(realm).client();
        return client.page_did_request_cookie(url, source);
    };
    m_worker_ipc->on_post_broadcast_channel_message = [realm = GC::RawRef { realm }](Web::HTML::BroadcastChannelMessage message) {
        auto& client = Bindings::principal_host_defined_page(realm).client();
        client.page_did_post_broadcast_channel_message(message);
    };
    m_worker_ipc->on_request_worker_agent = [realm = GC::RawRef { realm }](Web::Bindings::AgentType worker_type) -> Messages::WebWorkerClient::RequestWorkerAgentResponse {
        auto& client = Bindings::principal_host_defined_page(realm).client();
        auto response = client.request_worker_agent(worker_type);
        return { move(response.worker_handle), move(response.request_server_handle), move(response.image_decoder_handle) };
    };
    m_worker_ipc->on_worker_exception = [self = GC::Weak { *this }](String message, String filename, u32 lineno, u32 colno) {
        if (!self)
            return;
        // https://html.spec.whatwg.org/multipage/webappapis.html#report-an-exception
        // 7.2: If global implements DedicatedWorkerGlobalScope, queue a global task on the DOM manipulation task source with the global's associated Worker's relevant global object to run these steps:
        auto outside_settings = GC::Ref { *self->m_outside_settings };
        auto worker_event_target = GC::Ref { *self->m_worker_event_target };
        queue_global_task(Task::Source::DOMManipulation, outside_settings->global_object(), GC::create_function(outside_settings->heap(), [outside_settings, worker_event_target, message = move(message), filename = move(filename), lineno, colno]() {
            // 1. Let workerObject be the Worker object associated with global.
            auto& worker_object = as<Worker>(*worker_event_target);

            auto& realm = outside_settings->realm();

            // 2. Set notHandled to the result of firing an event named error at workerObject, using ErrorEvent, with the
            //    cancelable attribute initialized to true, and additional attributes initialized according to errorInfo.
            Bindings::ErrorEventInit event_init {};
            event_init.cancelable = true;
            event_init.message = message;
            event_init.filename = filename;
            event_init.lineno = lineno;
            event_init.colno = colno;
            event_init.error = JS::js_null();
            auto error = ErrorEvent::create(realm, EventNames::error, event_init);
            bool not_handled = worker_object.dispatch_event(error);

            // 3. If notHandled is true, then report exception for workerObject's relevant global object with omitError set to true.
            if (not_handled)
                as<WindowOrWorkerGlobalScopeMixin>(outside_settings->global_object()).report_an_exception(error, WindowOrWorkerGlobalScopeMixin::OmitError::Yes);
        }));
    };
    m_worker_ipc->on_worker_close = [self = GC::Weak { *this }]() {
        if (!self)
            return;
        self->release_startup_keep_alive();
    };
    m_worker_ipc->on_worker_script_load_success = [self = GC::Weak { *this }]() {
        if (!self)
            return;
        self->release_startup_keep_alive();
    };
    m_worker_ipc->on_worker_script_load_failure = [self = GC::Weak { *this }]() {
        if (!self)
            return;
        auto outside_settings = GC::Ref { *self->m_outside_settings };
        auto event_target = GC::Ref { *self->m_worker_event_target };
        // See: https://html.spec.whatwg.org/multipage/workers.html#worker-processing-model, onComplete handler for fetching script.
        // 1. Queue a global task on the DOM manipulation task source given worker's relevant global object to fire an event named error at worker.
        queue_global_task(Task::Source::DOMManipulation, outside_settings->global_object(), GC::create_function(outside_settings->heap(), [event_target, outside_settings]() {
            event_target->dispatch_event(DOM::Event::create(outside_settings->realm(), EventNames::error));
        }));
        self->release_startup_keep_alive();
    };
}

void WorkerAgentParent::release_startup_keep_alive()
{
    m_outside_settings->release_worker_agent_from_startup_keep_alive(*this);
}

void WorkerAgentParent::visit_edges(Cell::Visitor& visitor)
{
    Base::visit_edges(visitor);
    visitor.visit(m_message_port);
    visitor.visit(m_outside_port);
    visitor.visit(m_outside_settings);
    visitor.visit(m_worker_event_target);
}

}