/*
 * Copyright (C) 2019 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "config.h"
#include "WindowEventLoop.h"

#include "CommonVM.h"
#include "CustomElementReactionQueue.h"
#include "Document.h"
#include "HTMLSlotElement.h"
#include "Microtasks.h"
#include "MutationObserver.h"
#include "SecurityOrigin.h"

namespace WebCore {

static HashMap<String, WindowEventLoop*>& windowEventLoopMap()
{
    RELEASE_ASSERT(isMainThread());
    static NeverDestroyed<HashMap<String, WindowEventLoop*>> map;
    return map.get();
}

static String agentClusterKeyOrNullIfUnique(const SecurityOrigin& origin)
{
    auto computeKey = [&] {
        // https://html.spec.whatwg.org/multipage/webappapis.html#obtain-agent-cluster-key
        if (origin.isUnique())
            return origin.toString();
        RegistrableDomain registrableDomain { origin.data() };
        if (registrableDomain.isEmpty())
            return origin.toString();
        return makeString(origin.protocol(), "://", registrableDomain.string());
    };
    auto key = computeKey();
    if (key.isEmpty() || key == "null"_s)
        return { };
    return key;
}

Ref<WindowEventLoop> WindowEventLoop::eventLoopForSecurityOrigin(const SecurityOrigin& origin)
{
    auto key = agentClusterKeyOrNullIfUnique(origin);
    if (key.isNull())
        return create({ });

    auto addResult = windowEventLoopMap().add(key, nullptr);
    if (UNLIKELY(addResult.isNewEntry)) {
        auto newEventLoop = create(key);
        addResult.iterator->value = newEventLoop.ptr();
        return newEventLoop;
    }
    return *addResult.iterator->value;
}

inline Ref<WindowEventLoop> WindowEventLoop::create(const String& agentClusterKey)
{
    return adoptRef(*new WindowEventLoop(agentClusterKey));
}

inline WindowEventLoop::WindowEventLoop(const String& agentClusterKey)
    : m_agentClusterKey(agentClusterKey)
    , m_timer(*this, &WindowEventLoop::didReachTimeToRun)
    , m_perpetualTaskGroupForSimilarOriginWindowAgents(*this)
{
}

WindowEventLoop::~WindowEventLoop()
{
    if (m_agentClusterKey.isNull())
        return;
    auto didRemove = windowEventLoopMap().remove(m_agentClusterKey);
    RELEASE_ASSERT(didRemove);
}

void WindowEventLoop::scheduleToRun()
{
    m_timer.startOneShot(0_s);
}

bool WindowEventLoop::isContextThread() const
{
    return isMainThread();
}

MicrotaskQueue& WindowEventLoop::microtaskQueue()
{
    if (!m_microtaskQueue)
        m_microtaskQueue = makeUnique<MicrotaskQueue>(commonVM());
    return *m_microtaskQueue;
}

void WindowEventLoop::didReachTimeToRun()
{
    auto protectedThis = makeRef(*this); // Executing tasks may remove the last reference to this WindowEventLoop.
    run();
}

void WindowEventLoop::queueMutationObserverCompoundMicrotask()
{
    if (m_mutationObserverCompoundMicrotaskQueuedFlag)
        return;
    m_mutationObserverCompoundMicrotaskQueuedFlag = true;
    m_perpetualTaskGroupForSimilarOriginWindowAgents.queueMicrotask([this] {
        // We can't make a Ref to WindowEventLoop in the lambda capture as that would result in a reference cycle & leak.
        auto protectedThis = makeRef(*this);
        m_mutationObserverCompoundMicrotaskQueuedFlag = false;

        // FIXME: This check doesn't exist in the spec.
        if (m_deliveringMutationRecords)
            return;
        m_deliveringMutationRecords = true;
        MutationObserver::notifyMutationObservers(*this);
        m_deliveringMutationRecords = false;
    });
}

CustomElementQueue& WindowEventLoop::backupElementQueue()
{
    if (!m_processingBackupElementQueue) {
        m_processingBackupElementQueue = true;
        m_perpetualTaskGroupForSimilarOriginWindowAgents.queueMicrotask([this] {
            // We can't make a Ref to WindowEventLoop in the lambda capture as that would result in a reference cycle & leak.
            auto protectedThis = makeRef(*this);
            m_processingBackupElementQueue = false;
            ASSERT(m_customElementQueue);
            CustomElementReactionQueue::processBackupQueue(*m_customElementQueue);
        });
    }
    if (!m_customElementQueue)
        m_customElementQueue = makeUnique<CustomElementQueue>();
    return *m_customElementQueue;
}

} // namespace WebCore