/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2017-2021 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:
 * 
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
 * OWNER OR 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.
 */

#pragma once

#include "ScriptExecutionContext.h"
#include <memory>
#include <wtf/MessageQueue.h>

namespace WebCore {

class ModePredicate;
class WorkerOrWorkletGlobalScope;
class WorkerSharedTimer;

class WorkerRunLoop {
    WTF_MAKE_FAST_ALLOCATED;
public:
    enum class Type : bool { WorkerDedicatedRunLoop, WorkerMainRunLoop };

    virtual ~WorkerRunLoop() = default;

    virtual bool runInMode(WorkerOrWorkletGlobalScope*, const String& mode) = 0;
    virtual void postTaskAndTerminate(ScriptExecutionContext::Task&&) = 0;
    virtual void postTaskForMode(ScriptExecutionContext::Task&&, const String& mode) = 0;
    virtual void terminate() = 0;
    virtual bool terminated() const = 0;
    virtual Type type() const = 0;

    void postTask(ScriptExecutionContext::Task&&);
    void postDebuggerTask(ScriptExecutionContext::Task&&);

    WEBCORE_EXPORT static String defaultMode();

    unsigned long createUniqueId() { return ++m_uniqueId; }

private:
    unsigned long m_uniqueId { 0 };
};

class WorkerDedicatedRunLoop final : public WorkerRunLoop {
public:
    WorkerDedicatedRunLoop();
    ~WorkerDedicatedRunLoop();
    
    // Blocking call. Waits for tasks and timers, invokes the callbacks.
    void run(WorkerOrWorkletGlobalScope*);

    // Waits for a single task and returns.
    bool runInMode(WorkerOrWorkletGlobalScope*, const String& mode) final;
    MessageQueueWaitResult runInDebuggerMode(WorkerOrWorkletGlobalScope&);

    void terminate() final;
    bool terminated() const final { return m_messageQueue.killed(); }
    Type type() const final { return Type::WorkerDedicatedRunLoop; }

    void postTaskAndTerminate(ScriptExecutionContext::Task&&) final;
    WEBCORE_EXPORT void postTaskForMode(ScriptExecutionContext::Task&&, const String& mode) final;

    class Task {
        WTF_MAKE_NONCOPYABLE(Task); WTF_MAKE_FAST_ALLOCATED;
    public:
        Task(ScriptExecutionContext::Task&&, const String& mode);
        const String& mode() const { return m_mode; }

    private:
        void performTask(WorkerOrWorkletGlobalScope*);

        ScriptExecutionContext::Task m_task;
        String m_mode;

        friend class WorkerDedicatedRunLoop;
    };

private:
    friend class RunLoopSetup;
    MessageQueueWaitResult runInMode(WorkerOrWorkletGlobalScope*, const ModePredicate&);

    // Runs any clean up tasks that are currently in the queue and returns.
    // This should only be called when the context is closed or loop has been terminated.
    void runCleanupTasks(WorkerOrWorkletGlobalScope*);

    bool isBeingDebugged() const { return m_debugCount >= 1; }

    MessageQueue<Task> m_messageQueue;
    std::unique_ptr<WorkerSharedTimer> m_sharedTimer;
    int m_nestedCount { 0 };
    int m_debugCount { 0 };
};

class WorkerMainRunLoop final : public WorkerRunLoop, public CanMakeWeakPtr<WorkerMainRunLoop> {
public:
    WorkerMainRunLoop();

    void setGlobalScope(WorkerOrWorkletGlobalScope&);

    void terminate() final { m_terminated = true; }
    bool terminated() const final { return m_terminated; }

    bool runInMode(WorkerOrWorkletGlobalScope*, const String& mode);
    void postTaskAndTerminate(ScriptExecutionContext::Task&&) final;
    void postTaskForMode(ScriptExecutionContext::Task&&, const String& mode) final;
    Type type() const final { return Type::WorkerMainRunLoop; }

private:
    WeakPtr<WorkerOrWorkletGlobalScope> m_workerOrWorkletGlobalScope;
    bool m_terminated { false };
};

} // namespace WebCore

SPECIALIZE_TYPE_TRAITS_BEGIN(WebCore::WorkerDedicatedRunLoop)
    static bool isType(const WebCore::WorkerRunLoop& runLoop) { return runLoop.type() == WebCore::WorkerRunLoop::Type::WorkerDedicatedRunLoop; }
SPECIALIZE_TYPE_TRAITS_END()

SPECIALIZE_TYPE_TRAITS_BEGIN(WebCore::WorkerMainRunLoop)
    static bool isType(const WebCore::WorkerRunLoop& runLoop) { return runLoop.type() == WebCore::WorkerRunLoop::Type::WorkerMainRunLoop; }
SPECIALIZE_TYPE_TRAITS_END()