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

   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

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

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

namespace juce
{

MemoryAudioSource::MemoryAudioSource (AudioBuffer<float>& bufferToUse, bool copyMemory, bool shouldLoop)
    : isCurrentlyLooping (shouldLoop)
{
    if (copyMemory)
        buffer.makeCopyOf (bufferToUse);
    else
        buffer.setDataToReferTo (bufferToUse.getArrayOfWritePointers(),
                                 bufferToUse.getNumChannels(),
                                 bufferToUse.getNumSamples());
}

//==============================================================================
void MemoryAudioSource::prepareToPlay (int /*samplesPerBlockExpected*/, double /*sampleRate*/)
{
    position = 0;
}

void MemoryAudioSource::releaseResources()   {}

void MemoryAudioSource::getNextAudioBlock (const AudioSourceChannelInfo& bufferToFill)
{
    if (buffer.getNumSamples() == 0)
    {
        bufferToFill.clearActiveBufferRegion();
        return;
    }

    auto& dst = *bufferToFill.buffer;
    auto channels = jmin (dst.getNumChannels(), buffer.getNumChannels());
    int max = 0, pos = 0;
    auto n = buffer.getNumSamples();
    auto m = bufferToFill.numSamples;

    int i = position;
    for (; (i < n || isCurrentlyLooping) && (pos < m); i += max)
    {
        max = jmin (m - pos, n - (i % n));

        int ch = 0;
        for (; ch < channels; ++ch)
            dst.copyFrom (ch, bufferToFill.startSample + pos, buffer, ch, i % n, max);

        for (; ch < dst.getNumChannels(); ++ch)
            dst.clear (ch, bufferToFill.startSample + pos, max);

        pos += max;
    }

    if (pos < m)
        dst.clear (bufferToFill.startSample + pos, m - pos);

    position = i;
}

//==============================================================================
void MemoryAudioSource::setNextReadPosition (int64 newPosition)
{
    position = (int) newPosition;
}

int64 MemoryAudioSource::getNextReadPosition() const
{
    return position;
}

int64 MemoryAudioSource::getTotalLength() const
{
    return buffer.getNumSamples();
}

//==============================================================================
bool MemoryAudioSource::isLooping() const
{
    return isCurrentlyLooping;
}

void MemoryAudioSource::setLooping (bool shouldLoop)
{
    isCurrentlyLooping = shouldLoop;
}

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

static bool operator== (const AudioBuffer<float>& a, const AudioBuffer<float>& b)
{
    if (a.getNumChannels() != b.getNumChannels())
        return false;

    for (int channel = 0; channel < a.getNumChannels(); ++channel)
    {
        auto* aPtr = a.getReadPointer (channel);
        auto* bPtr = b.getReadPointer (channel);

        if (std::vector<float> (aPtr, aPtr + a.getNumSamples())
            != std::vector<float> (bPtr, bPtr + b.getNumSamples()))
        {
            return false;
        }
    }

    return true;
}

struct MemoryAudioSourceTests  : public UnitTest
{
    MemoryAudioSourceTests()  : UnitTest ("MemoryAudioSource", UnitTestCategories::audio)  {}

    void runTest() override
    {
        constexpr int blockSize = 512;
        AudioBuffer<float> bufferToFill { 2, blockSize };
        AudioSourceChannelInfo channelInfo { bufferToFill };

        beginTest ("A zero-length buffer produces silence, whether or not looping is enabled");
        {
            for (const bool enableLooping : { false, true })
            {
                AudioBuffer<float> buffer;
                MemoryAudioSource source { buffer, true, false };
                source.setLooping (enableLooping);
                source.prepareToPlay (blockSize, 44100.0);

                for (int i = 0; i < 2; ++i)
                {
                    play (source, channelInfo);
                    expect (isSilent (bufferToFill));
                }
            }
        }

        beginTest ("A short buffer without looping is played once and followed by silence");
        {
            auto buffer = getShortBuffer();
            MemoryAudioSource source { buffer, true, false };
            source.setLooping (false);
            source.prepareToPlay (blockSize, 44100.0);

            play (source, channelInfo);

            auto copy = buffer;
            copy.setSize (buffer.getNumChannels(), blockSize, true, true, false);

            expect (bufferToFill == copy);

            play (source, channelInfo);

            expect (isSilent (bufferToFill));
        }

        beginTest ("A short buffer with looping is played multiple times");
        {
            auto buffer = getShortBuffer();
            MemoryAudioSource source { buffer, true, false };
            source.setLooping (true);
            source.prepareToPlay (blockSize, 44100.0);

            play (source, channelInfo);

            for (int sample = 0; sample < buffer.getNumSamples(); ++sample)
                expect (bufferToFill.getSample (0, sample + buffer.getNumSamples()) == buffer.getSample (0, sample));

            expect (! isSilent (bufferToFill));
        }

        beginTest ("A long buffer without looping is played once");
        {
            auto buffer = getLongBuffer();
            MemoryAudioSource source { buffer, true, false };
            source.setLooping (false);
            source.prepareToPlay (blockSize, 44100.0);

            play (source, channelInfo);

            auto copy = buffer;
            copy.setSize (buffer.getNumChannels(), blockSize, true, true, false);

            expect (bufferToFill == copy);

            for (int i = 0; i < 10; ++i)
                play (source, channelInfo);

            expect (isSilent (bufferToFill));
        }

        beginTest ("A long buffer with looping is played multiple times");
        {
            auto buffer = getLongBuffer();
            MemoryAudioSource source { buffer, true, false };
            source.setLooping (true);
            source.prepareToPlay (blockSize, 44100.0);

            for (int i = 0; i < 100; ++i)
            {
                play (source, channelInfo);
                expect (bufferToFill.getSample (0, 0) == buffer.getSample (0, (i * blockSize) % buffer.getNumSamples()));
            }
        }
    }

    static AudioBuffer<float> getTestBuffer (int length)
    {
        AudioBuffer<float> buffer { 2, length };

        for (int channel = 0; channel < buffer.getNumChannels(); ++channel)
            for (int sample = 0; sample < buffer.getNumSamples(); ++sample)
                buffer.setSample (channel, sample, jmap ((float) sample, 0.0f, (float) length, -1.0f, 1.0f));

        return buffer;
    }

    static AudioBuffer<float> getShortBuffer()  { return getTestBuffer (5); }
    static AudioBuffer<float> getLongBuffer()   { return getTestBuffer (1000); }

    static void play (MemoryAudioSource& source, AudioSourceChannelInfo& info)
    {
        info.clearActiveBufferRegion();
        source.getNextAudioBlock (info);
    }

    static bool isSilent (const AudioBuffer<float>& b)
    {
        for (int channel = 0; channel < b.getNumChannels(); ++channel)
            if (b.findMinMax (channel, 0, b.getNumSamples()) != Range<float>{})
                return false;

        return true;
    }
};

static MemoryAudioSourceTests memoryAudioSourceTests;

#endif

} // namespace juce
