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//////////////////////////////////////////////////////////////////////////////

#include "pch.hpp"

#include "Stream.h"
#include "Streams.h"
#include <musikcore/debug.h>

using namespace musik::core::audio;
using namespace musik::core::sdk;
using namespace musik::core::io;

static std::string TAG = "Stream";

#define MIN_BUFFER_COUNT 30

Stream::Stream(int samplesPerChannel, double bufferLengthSeconds, StreamFlags options)
: options(options)
, samplesPerChannel(samplesPerChannel)
, bufferLengthSeconds(bufferLengthSeconds)
, bufferCount(0)
, decoderSampleRate(0)
, decoderChannels(0)
, decoderPosition(0)
, decoderSampleOffset(0)
, decoderSamplesRemain(0)
, done(false)
, capabilities(0)
, rawBuffer(nullptr) {
    if (((int) this->options & (int) StreamFlags::NoDSP) == 0) {
        dsps = streams::GetDspPlugins();
    }

    this->decoderBuffer = new Buffer();
    this->decoderBuffer->SetSamples(0);
}

Stream::~Stream() {
    delete[] rawBuffer;
    delete this->decoderBuffer;

    for (Buffer* buffer : this->recycledBuffers) {
        delete buffer;
    }

    for (Buffer* buffer : this->filledBuffers) {
        delete buffer;
    }
}

IStreamPtr Stream::Create(int samplesPerChannel, double bufferLengthSeconds, StreamFlags options) {
    return IStreamPtr(new Stream(samplesPerChannel, bufferLengthSeconds, options));
}

musik::core::audio::IStream* Stream::CreateUnmanaged(int samplesPerChannel, double bufferLengthSeconds, StreamFlags options) {
    return new Stream(samplesPerChannel, bufferLengthSeconds, options);
}

double Stream::SetPosition(double requestedSeconds) {
    double actualSeconds = this->decoder->SetPosition(requestedSeconds);

    if (actualSeconds != -1) {
        double rate = (double) this->decoderSampleRate;

        this->decoderPosition =
            (uint64_t)(actualSeconds * rate) * this->decoderChannels;

        /* move all the filled buffers back to the recycled queue */
        auto it = this->filledBuffers.begin();
        while (it != this->filledBuffers.end()) {
            this->recycledBuffers.push_back(*it);
            ++it;
        }

        this->filledBuffers.clear();
    }

    return actualSeconds;
}

double Stream::GetDuration() {
    return this->decoder ? this->decoder->GetDuration() : -1.0f;
}

int Stream::GetCapabilities() {
    return this->capabilities;
}

bool Stream::OpenStream(std::string uri, IOutput* output) {
    musik::debug::info(TAG, "opening " + uri);

    /* use our file stream abstraction to open the data at the
    specified URI */
    this->dataStream = DataStreamFactory::OpenSharedDataStream(uri.c_str(), OpenFlags::Read);

    if (!this->dataStream) {
        musik::debug::error(TAG, "failed to open " + uri);
        return false;
    }

    this->decoder = streams::GetDecoderForDataStream(this->dataStream);

    if (this->decoder) {
        /* if the output has a default/preferred sample rate, let the decoder know
        before sending samples. this way the decoder can resample the audio itself
        if it likes. */
        if (output) {
            int defaultOutputSampleRate = output->GetDefaultSampleRate();
            if (defaultOutputSampleRate > 0) {
                this->decoder->SetPreferredSampleRate(defaultOutputSampleRate);
            }
        }
        if (this->dataStream->CanPrefetch()) {
            this->capabilities |= (int) musik::core::sdk::Capability::Prebuffer;
            this->RefillInternalBuffers();
        }
        return true;
    }

    return false;
}

void Stream::Interrupt() {
    if (this->dataStream) {
        this->dataStream->Interrupt();
    }
}

void Stream::OnBufferProcessedByPlayer(IBuffer* buffer) {
    this->recycledBuffers.push_back((Buffer*) buffer);
}

bool Stream::GetNextBufferFromDecoder() {
    /* ask the decoder for some data */
    if (!this->decoder->GetBuffer(this->decoderBuffer)) {
        return false;
    }

    /* ensure our internal state is initialized */
    if (!this->rawBuffer) {
        this->decoderSampleRate = this->decoderBuffer->SampleRate();
        this->decoderChannels = this->decoderBuffer->Channels();
        this->samplesPerBuffer = samplesPerChannel * decoderChannels;

        this->bufferCount = std::max(MIN_BUFFER_COUNT, (int)(this->bufferLengthSeconds *
            (double)(this->decoderSampleRate / this->samplesPerBuffer)));

        this->rawBuffer = new float[bufferCount * this->samplesPerBuffer];
        int offset = 0;
        for (int i = 0; i < bufferCount; i++) {
            auto buffer = new Buffer(this->rawBuffer + offset, this->samplesPerBuffer);
            buffer->SetSampleRate(this->decoderSampleRate);
            buffer->SetChannels(this->decoderChannels);
            this->recycledBuffers.push_back(buffer);
            offset += this->samplesPerBuffer;
        }
    }

    return true;
}

inline Buffer* Stream::GetEmptyBuffer() {
    if (recycledBuffers.size()) {
        Buffer* target = recycledBuffers.front();
        recycledBuffers.pop_front();
        return target;
    }
    return nullptr;
}

IBuffer* Stream::GetNextProcessedOutputBuffer() {
    this->RefillInternalBuffers();

    /* in the normal case we have buffers available in the filled queue. */
    if (this->filledBuffers.size()) {
        Buffer* buffer = this->filledBuffers.front();
        this->filledBuffers.pop_front();

        for (std::shared_ptr<IDSP> dsp : this->dsps) {
            dsp->Process(buffer);
        }

        return buffer;
    }

    return nullptr;
}

void Stream::RefillInternalBuffers() {
    int recycled = (int) this->recycledBuffers.size();
    int count = 0;

    if (!this->rawBuffer) { /* not initialized */
        count = -1;
    }
    else {
        /* fill another chunk -- most of the time for file-based
        streams this will only be a single buffer. note the - 1
        part is to leave space for any potential remainder. */
        count = std::min(recycled - 1, std::max(1, this->bufferCount / 4));
    }

    Buffer* target = nullptr;
    long targetSampleOffset = 0;
    long targetSamplesRemain = 0;

    while (!this->done && (count > 0 || count == -1)) {
        /* get the next buffer, if the last one has been consumed... */
        if (this->decoderSamplesRemain <= 0) {
            if (!GetNextBufferFromDecoder()) {
                if (target) { /* very last buffer for this stream. */
                    target->SetSamples(targetSampleOffset);
                }
                this->done = true;
                break;
            }

            if (this->decoderBuffer->Samples() == 0) {
                continue;
            }

            this->decoderSamplesRemain = this->decoderBuffer->Samples();
            this->decoderSampleOffset = 0;
        }

        /* count will be < 0 on the very first pass through. let's try to
        fill 1/4 of our buffers */
        if (count < 0) {
            count = bufferCount / 4;
        }

        /* we're going to write to this guy... */
        if (!target) {
            target = this->GetEmptyBuffer();

            if (!target) {
                break; /* no available buffers. break out. */
            }

            target->SetSamples(0);

            target->SetPosition(
                ((double) this->decoderPosition) /
                ((double) this->decoderChannels) /
                ((double) this->decoderSampleRate));

            filledBuffers.push_back(target);
        }

        /* write to the target, from the decoder buffer. note that after the
        write the target may not be full, or the decoder buffer may not be
        empty. we'll go through the loop again... */
        targetSamplesRemain = this->samplesPerBuffer - targetSampleOffset;
        if (targetSamplesRemain > 0) {
            long samplesToCopy = std::min(this->decoderSamplesRemain, targetSamplesRemain);
            if (samplesToCopy > 0) {
                float* src = this->decoderBuffer->BufferPointer() + this->decoderSampleOffset;
                target->Copy(src, samplesToCopy, targetSampleOffset);

                this->decoderPosition += samplesToCopy;
                this->decoderSampleOffset += samplesToCopy;
                this->decoderSamplesRemain -= samplesToCopy;

                targetSampleOffset += samplesToCopy;

                if (targetSampleOffset == this->samplesPerBuffer) {
                    targetSampleOffset = 0;
                    target = nullptr;
                    --count; /* target buffer has been filled. */
                }
            }
        }
    }
}