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

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
   copyrightable work, you agree to the terms of the JUCE End User Licence
   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
   JUCE Privacy Policy: https://juce.com/juce-privacy-policy
   JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/

   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

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

namespace juce
{

ThreadedAnalyticsDestination::ThreadedAnalyticsDestination (const String& threadName)
    : dispatcher (threadName, *this)
{}

ThreadedAnalyticsDestination::~ThreadedAnalyticsDestination()
{
    // If you hit this assertion then the analytics thread has not been shut down
    // before this class is destroyed. Call stopAnalyticsThread() in your destructor!
    jassert (! dispatcher.isThreadRunning());
}

void ThreadedAnalyticsDestination::setBatchPeriod (int newBatchPeriodMilliseconds)
{
    dispatcher.batchPeriodMilliseconds = newBatchPeriodMilliseconds;
}

void ThreadedAnalyticsDestination::logEvent (const AnalyticsEvent& event)
{
    dispatcher.addToQueue (event);
}

void ThreadedAnalyticsDestination::startAnalyticsThread (int initialBatchPeriodMilliseconds)
{
    setBatchPeriod (initialBatchPeriodMilliseconds);
    dispatcher.startThread();
}

void ThreadedAnalyticsDestination::stopAnalyticsThread (int timeout)
{
    dispatcher.signalThreadShouldExit();
    stopLoggingEvents();
    dispatcher.stopThread (timeout);

    if (dispatcher.eventQueue.size() > 0)
        saveUnloggedEvents (dispatcher.eventQueue);
}

ThreadedAnalyticsDestination::EventDispatcher::EventDispatcher (const String& dispatcherThreadName,
                                                                ThreadedAnalyticsDestination& destination)
    : Thread (dispatcherThreadName),
      parent (destination)
{}

void ThreadedAnalyticsDestination::EventDispatcher::run()
{
    // We may have inserted some events into the queue (on the message thread)
    // before this thread has started, so make sure the old events are at the
    // front of the queue.
    {
        std::deque<AnalyticsEvent> restoredEventQueue;
        parent.restoreUnloggedEvents (restoredEventQueue);

        const ScopedLock lock (queueAccess);

        for (auto rit = restoredEventQueue.rbegin(); rit != restoredEventQueue.rend(); ++rit)
            eventQueue.push_front (*rit);
    }

    const int maxBatchSize = parent.getMaximumBatchSize();

    while (! threadShouldExit())
    {
        {
            const ScopedLock lock (queueAccess);

            const auto numEventsInBatch = eventsToSend.size();
            const auto freeBatchCapacity = maxBatchSize - numEventsInBatch;

            if (freeBatchCapacity > 0)
            {
                const auto numNewEvents = (int) eventQueue.size() - numEventsInBatch;

                if (numNewEvents > 0)
                {
                    const auto numEventsToAdd = jmin (numNewEvents, freeBatchCapacity);
                    const auto newBatchSize = numEventsInBatch + numEventsToAdd;

                    for (auto i = numEventsInBatch; i < newBatchSize; ++i)
                        eventsToSend.add (eventQueue[(size_t) i]);
                }
            }
        }

        const auto submissionTime = Time::getMillisecondCounter();

        if (! eventsToSend.isEmpty())
        {
            if (parent.logBatchedEvents (eventsToSend))
            {
                const ScopedLock lock (queueAccess);

                for (auto i = 0; i < eventsToSend.size(); ++i)
                    eventQueue.pop_front();

                eventsToSend.clearQuick();
            }
        }

        while (Time::getMillisecondCounter() - submissionTime < (uint32) batchPeriodMilliseconds.get())
        {
            if (threadShouldExit())
                return;

            Thread::sleep (100);
        }
    }
}

void ThreadedAnalyticsDestination::EventDispatcher::addToQueue (const AnalyticsEvent& event)
{
    const ScopedLock lock (queueAccess);
    eventQueue.push_back (event);
}


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

namespace DestinationTestHelpers
{
    //==============================================================================
    struct BasicDestination final : public ThreadedAnalyticsDestination
    {
        BasicDestination (std::deque<AnalyticsEvent>& loggedEvents,
                          std::deque<AnalyticsEvent>& unloggedEvents)
            : ThreadedAnalyticsDestination ("ThreadedAnalyticsDestinationTest"),
              loggedEventQueue (loggedEvents),
              unloggedEventStore (unloggedEvents)
        {
            startAnalyticsThread (20);
        }

        ~BasicDestination() override
        {
            stopAnalyticsThread (1000);
        }

        int getMaximumBatchSize() override
        {
            return 5;
        }

        void saveUnloggedEvents (const std::deque<AnalyticsEvent>& eventsToSave) override
        {
            unloggedEventStore = eventsToSave;
        }

        void restoreUnloggedEvents (std::deque<AnalyticsEvent>& restoredEventQueue) override
        {
            restoredEventQueue = unloggedEventStore;
        }

        bool logBatchedEvents (const Array<AnalyticsEvent>& events) override
        {
            jassert (events.size() <= getMaximumBatchSize());

            if (loggingIsEnabled)
            {
                const ScopedLock lock (eventQueueChanging);

                for (auto& event : events)
                    loggedEventQueue.push_back (event);

                return true;
            }

            return false;
        }

        void stopLoggingEvents() override {}

        void setLoggingEnabled (bool shouldLogEvents)
        {
            loggingIsEnabled = shouldLogEvents;
        }

        std::deque<AnalyticsEvent>& loggedEventQueue;
        std::deque<AnalyticsEvent>& unloggedEventStore;
        bool loggingIsEnabled = true;
        CriticalSection eventQueueChanging;
    };
}

//==============================================================================
struct ThreadedAnalyticsDestinationTests final : public UnitTest
{
    ThreadedAnalyticsDestinationTests()
        : UnitTest ("ThreadedAnalyticsDestination", UnitTestCategories::analytics)
    {}

    void compareEventQueues (const std::deque<AnalyticsDestination::AnalyticsEvent>& a,
                             const std::deque<AnalyticsDestination::AnalyticsEvent>& b)
    {
        const auto numEntries = a.size();
        expectEquals ((int) b.size(), (int) numEntries);

        for (size_t i = 0; i < numEntries; ++i)
        {
            expectEquals (a[i].name, b[i].name);
            expect (a[i].timestamp == b[i].timestamp);
        }
    }

    void runTest() override
    {
        std::deque<AnalyticsDestination::AnalyticsEvent> testEvents;

        for (int i = 0; i < 7; ++i)
            testEvents.push_back ({ String (i), 0, Time::getMillisecondCounter(), {}, "TestUser", {} });

        std::deque<AnalyticsDestination::AnalyticsEvent> loggedEvents, unloggedEvents;

        beginTest ("New events");

        {
            DestinationTestHelpers::BasicDestination destination (loggedEvents, unloggedEvents);

            for (auto& event : testEvents)
                destination.logEvent (event);

            size_t waitTime = 0, numLoggedEvents = 0;

            while (numLoggedEvents < testEvents.size())
            {
                if (waitTime > 4000)
                {
                    expect (waitTime < 4000);
                    break;
                }

                Thread::sleep (40);
                waitTime += 40;

                const ScopedLock lock (destination.eventQueueChanging);
                numLoggedEvents = loggedEvents.size();
            }
        }

        compareEventQueues (loggedEvents, testEvents);
        expect (unloggedEvents.size() == 0);

        loggedEvents.clear();

        beginTest ("Unlogged events");
        {
            DestinationTestHelpers::BasicDestination destination (loggedEvents, unloggedEvents);
            destination.setLoggingEnabled (false);

            for (auto& event : testEvents)
                destination.logEvent (event);
        }

        compareEventQueues (unloggedEvents, testEvents);
        expect (loggedEvents.size() == 0);
    }
};

static ThreadedAnalyticsDestinationTests threadedAnalyticsDestinationTests;

#endif

} // namespace juce