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

   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.

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

#pragma once

#include <JuceHeader.h>
#include <mutex>

//==============================================================================
class MainContentComponent final : public AudioAppComponent,
                                   private Timer
{
public:
    //==============================================================================
    MainContentComponent()
    {
        setSize (400, 400);
        setAudioChannels (0, 2);

        initGui();
        Desktop::getInstance().setScreenSaverEnabled (false);
        startTimer (1000);
    }

    ~MainContentComponent() override
    {
        shutdownAudio();
    }

    //==============================================================================
    void prepareToPlay (int bufferSize, double sampleRate) override
    {
        currentSampleRate = sampleRate;
        allocateBuffers (static_cast<size_t> (bufferSize));
        printHeader();
    }

    void releaseResources() override
    {
        a.clear();
        b.clear();
        c.clear();
        currentSampleRate = 0.0;
    }

    //==============================================================================
    void getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill) override
    {
        const double startTimeMs = getPreciseTimeMs();

        AudioBuffer<float>& outputAudio = *bufferToFill.buffer;
        std::size_t bufferSize = (std::size_t) outputAudio.getNumSamples();
        initialiseBuffers (bufferToFill, bufferSize);

        for (int ch = 0; ch < outputAudio.getNumChannels(); ++ch)
            crunchSomeNumbers (outputAudio.getWritePointer (ch), bufferSize, numLoopIterationsPerCallback);

        std::lock_guard<std::mutex> lock (metricMutex);

        double endTimeMs = getPreciseTimeMs();
        addCallbackMetrics (startTimeMs, endTimeMs);
    }

    //==============================================================================
    void addCallbackMetrics (double startTimeMs, double endTimeMs)
    {
        double runtimeMs = endTimeMs - startTimeMs;
        audioCallbackRuntimeMs.addValue (runtimeMs);

        if (runtimeMs > getPhysicalTimeLimitMs())
            numCallbacksOverPhysicalTimeLimit++;

        if (lastCallbackStartTimeMs > 0.0)
        {
            double gapMs = startTimeMs - lastCallbackStartTimeMs;
            audioCallbackGapMs.addValue (gapMs);

            if (gapMs > 1.5 * getPhysicalTimeLimitMs())
                numLateCallbacks++;
        }

        lastCallbackStartTimeMs = startTimeMs;
    }

    //==============================================================================
    void paint (Graphics& g) override
    {
        g.fillAll (Colours::black);
        g.setFont (FontOptions (16.0f));
        g.setColour (Colours::white);
        g.drawText ("loop iterations / audio callback",
                    getLocalBounds().withY (loopIterationsSlider.getHeight()), Justification::centred, true);
    }

    //==============================================================================
    void resized() override
    {
        loopIterationsSlider.setBounds (getLocalBounds().withSizeKeepingCentre (proportionOfWidth (0.9f), 50));
    }

private:
    //==============================================================================
    void initGui()
    {
        loopIterationsSlider.setSliderStyle (Slider::LinearBar);
        loopIterationsSlider.setRange (0, 30000, 250);
        loopIterationsSlider.setValue (15000);
        loopIterationsSlider.setColour (Slider::thumbColourId, Colours::white);
        loopIterationsSlider.setColour (Slider::textBoxTextColourId, Colours::grey);
        updateNumLoopIterationsPerCallback();
        addAndMakeVisible (loopIterationsSlider);
    }

    //==============================================================================
    void allocateBuffers (std::size_t bufferSize)
    {
        a.resize (bufferSize);
        b.resize (bufferSize);
        c.resize (bufferSize);
    }

    //==============================================================================
    void initialiseBuffers (const AudioSourceChannelInfo& bufferToFill, std::size_t bufferSize)
    {
        if (bufferSize != a.size())
        {
            jassertfalse;
            Logger::writeToLog ("WARNING: Unexpected buffer size received."
                                "expected: " + String (a.size()) +
                                ", actual: " + String (bufferSize));

            if (bufferSize > a.size())
                Logger::writeToLog ("WARNING: Need to allocate larger buffers on audio thread!");

            allocateBuffers (bufferSize);
        }

        bufferToFill.clearActiveBufferRegion();
        std::fill (a.begin(), a.end(), 0.09f);
        std::fill (b.begin(), b.end(), 0.1f );
        std::fill (c.begin(), c.end(), 0.11f);
    }

    //==============================================================================
    void crunchSomeNumbers (float* outBuffer, std::size_t bufferSize, int numIterations) noexcept
    {
        jassert (a.size() == bufferSize && b.size() == bufferSize && c.size() == bufferSize);

        for (int i = 0; i < numIterations; ++i)
        {
            FloatVectorOperations::multiply (c.data(), a.data(), b.data(), (int) bufferSize);
            FloatVectorOperations::addWithMultiply (outBuffer, b.data(), c.data(), (int) bufferSize);
        }
    }

    //==============================================================================
    void timerCallback() override
    {
        printAndResetPerformanceMetrics();
    }

    //==============================================================================
    void printHeader() const
    {
        Logger::writeToLog ("buffer size = " + String (a.size()) + " samples");
        Logger::writeToLog ("sample rate = " + String (currentSampleRate) + " Hz");
        Logger::writeToLog ("physical time limit / callback = " + String (getPhysicalTimeLimitMs() )+ " ms");
        Logger::writeToLog ("");
        Logger::writeToLog ("         | callback exec time / physLimit   | callback time gap / physLimit    | callback counters        ");
        Logger::writeToLog ("numLoops | avg     min     max     stddev   | avg     min     max     stddev   | called  late    >limit   ");
        Logger::writeToLog ("-----    | -----   -----   -----   -----    | -----   -----   -----   -----    | ---     ---     ---      ");
    }

    //==============================================================================
    void printAndResetPerformanceMetrics()
    {
        std::unique_lock<std::mutex> lock (metricMutex);

        auto runtimeMetric = audioCallbackRuntimeMs;
        auto gapMetric = audioCallbackGapMs;
        auto late = numLateCallbacks;
        auto overLimit = numCallbacksOverPhysicalTimeLimit;

        resetPerformanceMetrics();
        updateNumLoopIterationsPerCallback();

        lock.unlock();

        Logger::writeToLog (String (numLoopIterationsPerCallback).paddedRight (' ', 8) + " | "
                            + getPercentFormattedMetricString (runtimeMetric) + " | "
                            + getPercentFormattedMetricString (gapMetric) + " | "
                            + String (runtimeMetric.getCount()).paddedRight (' ', 8)
                            + String (late).paddedRight (' ', 8)
                            + String (overLimit).paddedRight (' ', 8) + " | ");
    }

    //==============================================================================
    String getPercentFormattedMetricString (const StatisticsAccumulator<double> metric) const
    {
        auto physTimeLimit = getPhysicalTimeLimitMs();

        return (String (100.0 * metric.getAverage()  / physTimeLimit, 1) + "%").paddedRight (' ', 8)
             + (String (100.0 * metric.getMinValue() / physTimeLimit, 1) + "%").paddedRight (' ', 8)
             + (String (100.0 * metric.getMaxValue() / physTimeLimit, 1) + "%").paddedRight (' ', 8)
             + String (metric.getStandardDeviation(), 3).paddedRight (' ', 8);
    }

    //==============================================================================
    void resetPerformanceMetrics()
    {
        audioCallbackRuntimeMs.reset();
        audioCallbackGapMs.reset();
        numLateCallbacks = 0;
        numCallbacksOverPhysicalTimeLimit = 0;
    }

    //==============================================================================
    void updateNumLoopIterationsPerCallback()
    {
        numLoopIterationsPerCallback = (int) loopIterationsSlider.getValue();
    }

    //==============================================================================
    static double getPreciseTimeMs() noexcept
    {
        return 1000.0 * (double) Time::getHighResolutionTicks() / (double) Time::getHighResolutionTicksPerSecond();
    }

    //==============================================================================
    double getPhysicalTimeLimitMs() const noexcept
    {
        return 1000.0 * (double) a.size() / currentSampleRate;
    }

    //==============================================================================
    std::vector<float> a, b, c; // must always be of size == current bufferSize
    double currentSampleRate = 0.0;

    StatisticsAccumulator<double> audioCallbackRuntimeMs;
    StatisticsAccumulator<double> audioCallbackGapMs;
    double lastCallbackStartTimeMs = 0.0;
    int numLateCallbacks = 0;
    int numCallbacksOverPhysicalTimeLimit = 0;
    int numLoopIterationsPerCallback;

    Slider loopIterationsSlider;
    std::mutex metricMutex;

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (MainContentComponent)
};