/*
  ==============================================================================

   This file is part of the JUCE library - "Jules' Utility Class Extensions"
   Copyright 2004-11 by Raw Material Software Ltd.

  ------------------------------------------------------------------------------

   JUCE can be redistributed and/or modified under the terms of the GNU General
   Public License (Version 2), as published by the Free Software Foundation.
   A copy of the license is included in the JUCE distribution, or can be found
   online at www.gnu.org/licenses.

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.rawmaterialsoftware.com/juce for more information.

  ==============================================================================
*/

ThreadPoolJob::ThreadPoolJob (const String& name)
    : jobName (name),
      pool (nullptr),
      shouldStop (false),
      isActive (false),
      shouldBeDeleted (false)
{
}

ThreadPoolJob::~ThreadPoolJob()
{
    // you mustn't delete a job while it's still in a pool! Use ThreadPool::removeJob()
    // to remove it first!
    jassert (pool == nullptr || ! pool->contains (this));
}

String ThreadPoolJob::getJobName() const
{
    return jobName;
}

void ThreadPoolJob::setJobName (const String& newName)
{
    jobName = newName;
}

void ThreadPoolJob::signalJobShouldExit()
{
    shouldStop = true;
}

//==============================================================================
class ThreadPool::ThreadPoolThread  : public Thread
{
public:
    ThreadPoolThread (ThreadPool& pool_)
        : Thread ("Pool"),
          pool (pool_)
    {
    }

    void run()
    {
        while (! threadShouldExit())
        {
            if (! pool.runNextJob())
                wait (500);
        }
    }

private:
    ThreadPool& pool;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ThreadPoolThread);
};

//==============================================================================
ThreadPool::ThreadPool (const int numThreads)
{
    jassert (numThreads > 0); // not much point having a pool without any threads!

    createThreads (numThreads);
}

ThreadPool::ThreadPool()
{
    createThreads (SystemStats::getNumCpus());
}

ThreadPool::~ThreadPool()
{
    removeAllJobs (true, 5000);
    stopThreads();
}

void ThreadPool::createThreads (int numThreads)
{
    for (int i = jmax (1, numThreads); --i >= 0;)
        threads.add (new ThreadPoolThread (*this));

    for (int i = threads.size(); --i >= 0;)
        threads.getUnchecked(i)->startThread();
}

void ThreadPool::stopThreads()
{
    for (int i = threads.size(); --i >= 0;)
        threads.getUnchecked(i)->signalThreadShouldExit();

    for (int i = threads.size(); --i >= 0;)
        threads.getUnchecked(i)->stopThread (500);
}

void ThreadPool::addJob (ThreadPoolJob* const job, const bool deleteJobWhenFinished)
{
    jassert (job != nullptr);
    jassert (job->pool == nullptr);

    if (job->pool == nullptr)
    {
        job->pool = this;
        job->shouldStop = false;
        job->isActive = false;
        job->shouldBeDeleted = deleteJobWhenFinished;

        {
            const ScopedLock sl (lock);
            jobs.add (job);
        }

        for (int i = threads.size(); --i >= 0;)
            threads.getUnchecked(i)->notify();
    }
}

int ThreadPool::getNumJobs() const
{
    return jobs.size();
}

ThreadPoolJob* ThreadPool::getJob (const int index) const
{
    const ScopedLock sl (lock);
    return jobs [index];
}

bool ThreadPool::contains (const ThreadPoolJob* const job) const
{
    const ScopedLock sl (lock);
    return jobs.contains (const_cast <ThreadPoolJob*> (job));
}

bool ThreadPool::isJobRunning (const ThreadPoolJob* const job) const
{
    const ScopedLock sl (lock);
    return jobs.contains (const_cast <ThreadPoolJob*> (job)) && job->isActive;
}

bool ThreadPool::waitForJobToFinish (const ThreadPoolJob* const job,
                                     const int timeOutMs) const
{
    if (job != nullptr)
    {
        const uint32 start = Time::getMillisecondCounter();

        while (contains (job))
        {
            if (timeOutMs >= 0 && Time::getMillisecondCounter() >= start + timeOutMs)
                return false;

            jobFinishedSignal.wait (2);
        }
    }

    return true;
}

bool ThreadPool::removeJob (ThreadPoolJob* const job,
                            const bool interruptIfRunning,
                            const int timeOutMs)
{
    bool dontWait = true;
    OwnedArray<ThreadPoolJob> deletionList;

    if (job != nullptr)
    {
        const ScopedLock sl (lock);

        if (jobs.contains (job))
        {
            if (job->isActive)
            {
                if (interruptIfRunning)
                    job->signalJobShouldExit();

                dontWait = false;
            }
            else
            {
                jobs.removeValue (job);
                addToDeleteList (deletionList, job);
            }
        }
    }

    return dontWait || waitForJobToFinish (job, timeOutMs);
}

bool ThreadPool::removeAllJobs (const bool interruptRunningJobs, const int timeOutMs,
                                ThreadPool::JobSelector* selectedJobsToRemove)
{
    Array <ThreadPoolJob*> jobsToWaitFor;

    {
        OwnedArray<ThreadPoolJob> deletionList;

        {
            const ScopedLock sl (lock);

            for (int i = jobs.size(); --i >= 0;)
            {
                ThreadPoolJob* const job = jobs.getUnchecked(i);

                if (selectedJobsToRemove == nullptr || selectedJobsToRemove->isJobSuitable (job))
                {
                    if (job->isActive)
                    {
                        jobsToWaitFor.add (job);

                        if (interruptRunningJobs)
                            job->signalJobShouldExit();
                    }
                    else
                    {
                        jobs.remove (i);
                        addToDeleteList (deletionList, job);
                    }
                }
            }
        }
    }

    const uint32 start = Time::getMillisecondCounter();

    for (;;)
    {
        for (int i = jobsToWaitFor.size(); --i >= 0;)
        {
            ThreadPoolJob* const job = jobsToWaitFor.getUnchecked (i);

            if (! isJobRunning (job))
                jobsToWaitFor.remove (i);
        }

        if (jobsToWaitFor.size() == 0)
            break;

        if (timeOutMs >= 0 && Time::getMillisecondCounter() >= start + timeOutMs)
            return false;

        jobFinishedSignal.wait (20);
    }

    return true;
}

StringArray ThreadPool::getNamesOfAllJobs (const bool onlyReturnActiveJobs) const
{
    StringArray s;
    const ScopedLock sl (lock);

    for (int i = 0; i < jobs.size(); ++i)
    {
        const ThreadPoolJob* const job = jobs.getUnchecked(i);
        if (job->isActive || ! onlyReturnActiveJobs)
            s.add (job->getJobName());
    }

    return s;
}

bool ThreadPool::setThreadPriorities (const int newPriority)
{
    bool ok = true;

    for (int i = threads.size(); --i >= 0;)
        if (! threads.getUnchecked(i)->setPriority (newPriority))
            ok = false;

    return ok;
}

ThreadPoolJob* ThreadPool::pickNextJobToRun()
{
    OwnedArray<ThreadPoolJob> deletionList;

    {
        const ScopedLock sl (lock);

        for (int i = 0; i < jobs.size(); ++i)
        {
            ThreadPoolJob* job = jobs[i];

            if (job != nullptr && ! job->isActive)
            {
                if (job->shouldStop)
                {
                    jobs.remove (i);
                    addToDeleteList (deletionList, job);
                    --i;
                    continue;
                }

                job->isActive = true;
                return job;
            }
        }
    }

    return nullptr;
}

bool ThreadPool::runNextJob()
{
    ThreadPoolJob* const job = pickNextJobToRun();

    if (job == nullptr)
        return false;

    ThreadPoolJob::JobStatus result = ThreadPoolJob::jobHasFinished;

    JUCE_TRY
    {
        result = job->runJob();
    }
    JUCE_CATCH_ALL_ASSERT

    OwnedArray<ThreadPoolJob> deletionList;

    {
        const ScopedLock sl (lock);

        if (jobs.contains (job))
        {
            job->isActive = false;

            if (result != ThreadPoolJob::jobNeedsRunningAgain || job->shouldStop)
            {
                jobs.removeValue (job);
                addToDeleteList (deletionList, job);

                jobFinishedSignal.signal();
            }
            else
            {
                // move the job to the end of the queue if it wants another go
                jobs.move (jobs.indexOf (job), -1);
            }
        }
    }

    return true;
}

void ThreadPool::addToDeleteList (OwnedArray<ThreadPoolJob>& deletionList, ThreadPoolJob* const job) const
{
    job->shouldStop = true;
    job->pool = nullptr;

    if (job->shouldBeDeleted)
        deletionList.add (job);
}