/***
    This file is part of snapcast
    Copyright (C) 2014-2020  Johannes Pohl

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program 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.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
***/

#include "stream.hpp"
#include "common/aixlog.hpp"
#include "time_provider.hpp"
#include <cmath>
#include <iostream>
#include <string.h>

using namespace std;
namespace cs = chronos;

static constexpr auto LOG_TAG = "Stream";
static constexpr auto kCorrectionBegin = 100us;


Stream::Stream(const SampleFormat& in_format, const SampleFormat& out_format)
    : in_format_(in_format), median_(0), shortMedian_(0), lastUpdate_(0), playedFrames_(0), bufferMs_(cs::msec(500)), soxr_(nullptr), frame_delta_(0),
      hard_sync_(true)
{
    buffer_.setSize(500);
    shortBuffer_.setSize(100);
    miniBuffer_.setSize(20);

    format_ = in_format_;
    if (out_format.isInitialized())
    {
        format_.setFormat(out_format.rate() != 0 ? out_format.rate() : format_.rate(), out_format.bits() != 0 ? out_format.bits() : format_.bits(),
                          out_format.channels() != 0 ? out_format.channels() : format_.channels());
    }

    /*
    48000     x
    ------- = -----
    47999,2   x - 1

    x = 1,000016667 / (1,000016667 - 1)
    */
    // setRealSampleRate(format_.rate());

    if ((format_.rate() != in_format_.rate()) || (format_.bits() != in_format_.bits()))
    {
        LOG(INFO, LOG_TAG) << "Resampling from " << in_format_.getFormat() << " to " << format_.getFormat() << "\n";
        soxr_error_t error;

        soxr_datatype_t in_type = SOXR_INT16_I;
        soxr_datatype_t out_type = SOXR_INT16_I;
        if (in_format_.sampleSize() > 2)
            in_type = SOXR_INT32_I;
        if (format_.sampleSize() > 2)
            out_type = SOXR_INT32_I;
        soxr_io_spec_t iospec = soxr_io_spec(in_type, out_type);
        // HQ should be fine: http://sox.sourceforge.net/Docs/FAQ
        soxr_quality_spec_t q_spec = soxr_quality_spec(SOXR_HQ, 0);
        soxr_ = soxr_create(static_cast<double>(in_format_.rate()), static_cast<double>(format_.rate()), format_.channels(), &error, &iospec, &q_spec, NULL);
        if (error)
        {
            LOG(ERROR, LOG_TAG) << "Error soxr_create: " << error << "\n";
            soxr_ = nullptr;
        }
        // initialize the buffer with 20ms (~latency of the reampler)
        resample_buffer_.resize(format_.frameSize() * ceil(format_.msRate()) * 20);
    }
}


Stream::~Stream()
{
    if (soxr_)
        soxr_delete(soxr_);
}


void Stream::setRealSampleRate(double sampleRate)
{
    if (sampleRate == format_.rate())
    {
        correctAfterXFrames_ = 0;
    }
    else
    {
        correctAfterXFrames_ = round((format_.rate() / sampleRate) / (format_.rate() / sampleRate - 1.));
        // LOG(TRACE, LOG_TAG) << "Correct after X: " << correctAfterXFrames_ << " (Real rate: " << sampleRate << ", rate: " << format_.rate() << ")\n";
    }
}


void Stream::setBufferLen(size_t bufferLenMs)
{
    bufferMs_ = cs::msec(bufferLenMs);
}


void Stream::clearChunks()
{
    while (chunks_.size() > 0)
        chunks_.pop();
    resetBuffers();
}


void Stream::addChunk(unique_ptr<msg::PcmChunk> chunk)
{
    // drop chunks that should have been played 10s before. Just in case, this shouldn't happen.
    while (!chunks_.empty())
    {
        auto first_chunk = chunks_.front();
        cs::usec age = std::chrono::duration_cast<cs::usec>(TimeProvider::serverNow() - first_chunk->start());
        if (age > 10s + bufferMs_)
            chunks_.pop();
        else
            break;
    }

    // LOG(DEBUG, LOG_TAG) << "new chunk: " << chunk->durationMs() << " ms, Chunks: " << chunks_.size() << "\n";

    if (soxr_ == nullptr)
    {
        chunks_.push(move(chunk));
    }
    else
    {
        if (in_format_.bits() == 24)
        {
            // sox expects 32 bit input, shift 8 bits left
            int32_t* frames = (int32_t*)chunk->payload;
            for (size_t n = 0; n < chunk->getSampleCount(); ++n)
                frames[n] = frames[n] << 8;
        }

        size_t idone;
        size_t odone;
        auto resample_buffer_framesize = resample_buffer_.size() / format_.frameSize();
        auto error = soxr_process(soxr_, chunk->payload, chunk->getFrameCount(), &idone, resample_buffer_.data(), resample_buffer_framesize, &odone);
        if (error)
        {
            LOG(ERROR, LOG_TAG) << "Error soxr_process: " << error << "\n";
        }
        else
        {
            LOG(TRACE, LOG_TAG) << "Resample idone: " << idone << "/" << chunk->getFrameCount() << ", odone: " << odone << "/"
                                << resample_buffer_.size() / format_.frameSize() << ", delay: " << soxr_delay(soxr_) << "\n";

            // some data has been resampled (odone frames) and some is still in the pipe (soxr_delay frames)
            if (odone > 0)
            {
                // get the resamples ts from the input ts
                auto input_end_ts = chunk->start() + chunk->duration<std::chrono::microseconds>();
                double resampled_ms = (odone + soxr_delay(soxr_)) / format_.msRate();
                auto resampled_start = input_end_ts - std::chrono::microseconds(static_cast<int>(resampled_ms * 1000.));

                auto resampled_chunk = new msg::PcmChunk(format_, 0);
                auto us = chrono::duration_cast<chrono::microseconds>(resampled_start.time_since_epoch()).count();
                resampled_chunk->timestamp.sec = us / 1000000;
                resampled_chunk->timestamp.usec = us % 1000000;

                // copy from the resample_buffer to the resampled chunk
                resampled_chunk->payloadSize = odone * format_.frameSize();
                resampled_chunk->payload = (char*)realloc(resampled_chunk->payload, resampled_chunk->payloadSize);
                memcpy(resampled_chunk->payload, resample_buffer_.data(), resampled_chunk->payloadSize);

                if (format_.bits() == 24)
                {
                    // sox has quantized to 32 bit, shift 8 bits right
                    int32_t* frames = (int32_t*)resampled_chunk->payload;
                    for (size_t n = 0; n < resampled_chunk->getSampleCount(); ++n)
                    {
                        // +128 to round to the nearest so that quantisation steps are distributed evenly
                        frames[n] = (frames[n] + 128) >> 8;
                        if (frames[n] > 0x7fffffff)
                            frames[n] = 0x7fffffff;
                    }
                }
                chunks_.push(shared_ptr<msg::PcmChunk>(resampled_chunk));

                // check if the resample_buffer is large enough, or if soxr was using all available space
                if (odone == resample_buffer_framesize)
                {
                    // buffer for resampled data too small, add space for 5ms
                    resample_buffer_.resize(resample_buffer_.size() + format_.frameSize() * ceil(format_.msRate()) * 5);
                    LOG(DEBUG, LOG_TAG) << "Resample buffer completely filled, adding space for 5ms; new buffer size: " << resample_buffer_.size()
                                        << " bytes\n";
                }

                // //LOG(TRACE, LOG_TAG) << "ts: " << out->timestamp.sec << "s, " << out->timestamp.usec/1000.f << " ms, duration: " << odone / format_.msRate()
                // << "\n";
                // int64_t next_us = us + static_cast<int64_t>(odone / format_.msRate() * 1000);
                // LOG(TRACE, LOG_TAG) << "ts: " << us << ", next: " << next_us << ", diff: " << next_us_ - us << "\n";
                // next_us_ = next_us;
            }
        }
    }
}


bool Stream::waitForChunk(const std::chrono::milliseconds& timeout) const
{
    return chunks_.wait_for(timeout);
}


void Stream::getSilentPlayerChunk(void* outputBuffer, uint32_t frames) const
{
    memset(outputBuffer, 0, frames * format_.frameSize());
}


cs::time_point_clk Stream::getNextPlayerChunk(void* outputBuffer, uint32_t frames)
{
    if (!chunk_ && !chunks_.try_pop(chunk_))
        throw 0;

    cs::time_point_clk tp = chunk_->start();
    uint32_t read = 0;
    while (read < frames)
    {
        read += chunk_->readFrames(static_cast<char*>(outputBuffer) + read * format_.frameSize(), frames - read);
        if (chunk_->isEndOfChunk() && !chunks_.try_pop(chunk_))
            throw 0;
    }
    return tp;
}


cs::time_point_clk Stream::getNextPlayerChunk(void* outputBuffer, uint32_t frames, int32_t framesCorrection)
{
    if (framesCorrection < 0 && frames + framesCorrection <= 0)
    {
        // Avoid underflow in new char[] constructor.
        framesCorrection = -frames + 1;
    }

    if (framesCorrection == 0)
        return getNextPlayerChunk(outputBuffer, frames);

    frame_delta_ -= framesCorrection;

    uint32_t toRead = frames + framesCorrection;
    if (toRead * format_.frameSize() > read_buffer_.size())
        read_buffer_.resize(toRead * format_.frameSize());
    cs::time_point_clk tp = getNextPlayerChunk(read_buffer_.data(), toRead);

    const auto max = framesCorrection < 0 ? frames : toRead;
    // Divide the buffer into one more slice than frames that need to be dropped.
    // We will drop/repeat 0 frames from the first slice, 1 frame from the second, ..., and framesCorrection frames from the last slice.
    size_t slices = abs(framesCorrection) + 1;
    if (slices > max)
    {
        // We cannot have more slices than frames, because that would cause
        // size = 0 -> pos = 0 -> pos - n < 0 in the loop below
        // Overwriting slices effectively corrects less frames than asked for in framesCorrection.
        slices = max;
    }
    // Size of each slice. The last slice may be bigger.
    int size = max / slices;

    // LOG(TRACE, LOG_TAG) << "getNextPlayerChunk, frames: " << frames << ", correction: " << framesCorrection << " (" << toRead << "), slices: " << slices
    // << "\n";

    size_t pos = 0;
    for (size_t n = 0; n < slices; ++n)
    {
        // Adjust size in the last iteration, because the last slice may be bigger
        if (n + 1 == slices)
            size = max - pos;

        if (framesCorrection < 0)
        {
            // Read one frame less per slice from the input, but write a duplicated frame per slice to the output
            // LOG(TRACE, LOG_TAG) << "duplicate - requested: " << frames << ", read: " << toRead << ", slice: " << n << ", size: " << size << ", out pos: " <<
            // pos << ", source pos: " << pos - n << "\n";
            memcpy(static_cast<char*>(outputBuffer) + pos * format_.frameSize(), read_buffer_.data() + (pos - n) * format_.frameSize(),
                   size * format_.frameSize());
        }
        else
        {
            // Read all input frames, but skip a frame per slice when writing to the output.
            // LOG(TRACE, LOG_TAG) << "remove - requested: " << frames << ", read: " << toRead << ", slice: " << n << ", size: " << size << ", out pos: " << pos
            // - n << ", source pos: " << pos << "\n";
            memcpy(static_cast<char*>(outputBuffer) + (pos - n) * format_.frameSize(), read_buffer_.data() + pos * format_.frameSize(),
                   size * format_.frameSize());
        }
        pos += size;
    }

    return tp;
}


void Stream::updateBuffers(int age)
{
    buffer_.add(age);
    miniBuffer_.add(age);
    shortBuffer_.add(age);
}


void Stream::resetBuffers()
{
    buffer_.clear();
    miniBuffer_.clear();
    shortBuffer_.clear();
}


bool Stream::getPlayerChunk(void* outputBuffer, const cs::usec& outputBufferDacTime, uint32_t frames)
{
    if (outputBufferDacTime > bufferMs_)
    {
        LOG(INFO, LOG_TAG) << "outputBufferDacTime > bufferMs: " << cs::duration<cs::msec>(outputBufferDacTime) << " > " << cs::duration<cs::msec>(bufferMs_)
                           << "\n";
        return false;
    }

    time_t now = time(nullptr);
    if (!chunk_ && !chunks_.try_pop(chunk_))
    {
        if (now != lastUpdate_)
        {
            lastUpdate_ = now;
            LOG(INFO, LOG_TAG) << "no chunks available\n";
        }
        return false;
    }

    /// we have a chunk
    /// age = chunk age (server now - rec time: some positive value) - buffer (e.g. 1000ms) + time to DAC
    /// age = 0 => play now
    /// age < 0 => play in -age => wait for a while, play silence in the meantime
    /// age > 0 => too old      => throw them away

    try
    {
        if (hard_sync_)
        {
            cs::nsec req_chunk_duration = cs::nsec(static_cast<cs::nsec::rep>(frames / format_.nsRate()));
            cs::usec age = std::chrono::duration_cast<cs::usec>(TimeProvider::serverNow() - chunk_->start()) - bufferMs_ + outputBufferDacTime;
            // LOG(INFO, LOG_TAG) << "age: " << age.count() / 1000 << ", buffer: " <<
            // std::chrono::duration_cast<chrono::milliseconds>(req_chunk_duration).count() << "\n";
            if (age < -req_chunk_duration)
            {
                // the oldest chunk (top of the stream) is too young for the buffer
                // e.g. age = -100ms (=> should be played in 100ms)
                // but the requested chunk duration is 50ms, so there is not data in this iteration available
                getSilentPlayerChunk(outputBuffer, frames);
                return true;
            }
            else
            {
                if (age.count() > 0)
                {
                    LOG(DEBUG, LOG_TAG) << "age > 0: " << age.count() / 1000 << "ms\n";
                    // age > 0: the top of the stream is too old. We must fast foward.
                    // delete the current chunk, it's too old. This will avoid an endless loop if there is no chunk in the queue.
                    chunk_ = nullptr;
                    while (chunks_.try_pop(chunk_))
                    {
                        age = std::chrono::duration_cast<cs::usec>(TimeProvider::serverNow() - chunk_->start()) - bufferMs_ + outputBufferDacTime;
                        LOG(DEBUG, LOG_TAG) << "age: " << age.count() / 1000 << ", requested chunk_duration: "
                                            << std::chrono::duration_cast<std::chrono::milliseconds>(req_chunk_duration).count()
                                            << ", duration: " << chunk_->duration<std::chrono::milliseconds>().count() << "\n";
                        if (age.count() <= 0)
                            break;
                    }
                }

                if (age.count() <= 0)
                {
                    // the oldest chunk (top of the stream) can be played in this iteration
                    // e.g. age = -20ms (=> should be played in 20ms)
                    // and the current chunk duration is 50ms, so we need to play 20ms silence (as we don't have data)
                    // and can play 30ms of the stream
                    uint32_t silent_frames = static_cast<size_t>(-chunk_->format.nsRate() * std::chrono::duration_cast<cs::nsec>(age).count());
                    bool result = (silent_frames <= frames);
                    silent_frames = std::min(silent_frames, frames);
                    LOG(DEBUG, LOG_TAG) << "Silent frames: " << silent_frames << ", frames: " << frames
                                        << ", age: " << std::chrono::duration_cast<cs::usec>(age).count() / 1000. << "\n";
                    getSilentPlayerChunk(outputBuffer, silent_frames);
                    getNextPlayerChunk((char*)outputBuffer + (chunk_->format.frameSize() * silent_frames), frames - silent_frames);

                    if (result)
                    {
                        hard_sync_ = false;
                        resetBuffers();
                    }
                    return true;
                }
                return false;
            }
        }

        // sample rate correction
        // framesCorrection = number of frames to be read more or less to get in-sync
        int32_t framesCorrection = 0;
        if (correctAfterXFrames_ != 0)
        {
            playedFrames_ += frames;
            if (playedFrames_ >= (uint32_t)abs(correctAfterXFrames_))
            {
                framesCorrection = static_cast<int32_t>(playedFrames_) / correctAfterXFrames_;
                playedFrames_ %= abs(correctAfterXFrames_);
            }
        }

        cs::usec age = std::chrono::duration_cast<cs::usec>(TimeProvider::serverNow() - getNextPlayerChunk(outputBuffer, frames, framesCorrection) - bufferMs_ +
                                                            outputBufferDacTime);

        setRealSampleRate(format_.rate());
        // check if we need a hard sync
        if (buffer_.full() && (cs::usec(abs(median_)) > cs::msec(2)) && (cs::abs(age) > cs::usec(500)))
        {
            LOG(INFO, LOG_TAG) << "pBuffer->full() && (abs(median_) > 2): " << median_ << "\n";
            hard_sync_ = true;
        }
        else if (shortBuffer_.full() && (cs::usec(abs(shortMedian_)) > cs::msec(5)) && (cs::abs(age) > cs::usec(500)))
        {
            LOG(INFO, LOG_TAG) << "pShortBuffer->full() && (abs(shortMedian_) > 5): " << shortMedian_ << "\n";
            hard_sync_ = true;
        }
        else if (miniBuffer_.full() && (cs::usec(abs(miniBuffer_.median())) > cs::msec(50)) && (cs::abs(age) > cs::usec(500)))
        {
            LOG(INFO, LOG_TAG) << "pMiniBuffer->full() && (abs(pMiniBuffer->mean()) > 50): " << miniBuffer_.median() << "\n";
            hard_sync_ = true;
        }
        else if (cs::abs(age) > 500ms)
        {
            LOG(INFO, LOG_TAG) << "abs(age > 500): " << cs::abs(age).count() << "\n";
            hard_sync_ = true;
        }
        else if (shortBuffer_.full())
        {
            // No hard sync needed
            // Check if we need a samplerate correction (change playback speed (soft sync))
            auto miniMedian = miniBuffer_.median();
            if ((cs::usec(shortMedian_) > kCorrectionBegin) && (cs::usec(miniMedian) > cs::usec(50)) && (cs::usec(age) > cs::usec(50)))
            {
                double rate = (shortMedian_ / 100) * 0.00005;
                rate = 1.0 - std::min(rate, 0.0005);
                // LOG(INFO, LOG_TAG) << "Rate: " << rate << "\n";
                // we are late (age > 0), this means we are not playing fast enough
                // => the real sample rate seems to be lower, we have to drop some frames
                setRealSampleRate(format_.rate() * rate); // 0.9999);
            }
            else if ((cs::usec(shortMedian_) < -kCorrectionBegin) && (cs::usec(miniMedian) < -cs::usec(50)) && (cs::usec(age) < -cs::usec(50)))
            {
                double rate = (-shortMedian_ / 100) * 0.00005;
                rate = 1.0 + std::min(rate, 0.0005);
                // LOG(INFO, LOG_TAG) << "Rate: " << rate << "\n";
                // we are early (age > 0), this means we are playing too fast
                // => the real sample rate seems to be higher, we have to insert some frames
                setRealSampleRate(format_.rate() * rate); // 1.0001);
            }
        }

        updateBuffers(age.count());

        // print sync stats
        if (now != lastUpdate_)
        {
            lastUpdate_ = now;
            median_ = buffer_.median();
            shortMedian_ = shortBuffer_.median();
            LOG(INFO, LOG_TAG) << "Chunk: " << age.count() / 100 << "\t" << miniBuffer_.median() / 100 << "\t" << shortMedian_ / 100 << "\t" << median_ / 100
                               << "\t" << buffer_.size() << "\t" << cs::duration<cs::msec>(outputBufferDacTime) << "\t" << frame_delta_ << "\n";
            frame_delta_ = 0;
        }
        return (abs(cs::duration<cs::msec>(age)) < 500);
    }
    catch (int e)
    {
        LOG(INFO) << "Exception\n";
        hard_sync_ = true;
        return false;
    }
}