/* SPU2-X, A plugin for Emulating the Sound Processing Unit of the Playstation 2
* Developed and maintained by the Pcsx2 Development Team.
*
* Original portions from SPU2ghz are (c) 2008 by David Quintana [gigaherz]
*
* SPU2-X is free software: you can redistribute it and/or modify it under the terms
* of the GNU Lesser General Public License as published by the Free Software Found-
* ation, either version 3 of the License, or (at your option) any later version.
*
* SPU2-X 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with SPU2-X.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "XSFCommon.h"

#include "../types.h"
#include "SoundTouch/SoundTouch.h"
#include "SndOut.h"

static std::unique_ptr<soundtouch::SoundTouch> pSoundTouch;
static int ts_stats_stretchblocks = 0;
static int ts_stats_normalblocks = 0;
static int ts_stats_logcounter = 0;

// data prediction amount, used to "commit" data that hasn't
// finished timestretch processing.
int32_t SndBuffer::m_predictData;

// records last buffer status (fill %, range -100 to 100, with 0 being 50% full)
float SndBuffer::lastPct;
float SndBuffer::lastEmergencyAdj;

float SndBuffer::cTempo = 1;
float SndBuffer::eTempo = 1;
int SndBuffer::freezeTempo = 0;

void SndBuffer::PredictDataWrite(int samples)
{
	m_predictData += samples;
}

// Calculate the buffer status percentage.
// Returns range from -1.0 to 1.0
//    1.0 = buffer overflow!
//    0.0 = buffer nominal (50% full)
//   -1.0 = buffer underflow!
float SndBuffer::GetStatusPct()
{
	// Get the buffer status of the output driver too, so that we can
	// obtain a more accurate overall buffer status.

	int drvempty = 0;
	//int drvempty = mods[OutputModule]->GetEmptySampleCount(); // / 2;
	//TODO

	//ConLog( "Data %d >>> driver: %d   predict: %d\n", data, drvempty, predictData );

	float result = static_cast<float>(m_data + m_predictData - drvempty) - (m_size / 2);
	result /= m_size / 2;
	return result;
}

void SndBuffer::UpdateTempoChange()
{
	if (--freezeTempo > 0)
		return;

	float statusPct = GetStatusPct();
	float pctChange = statusPct - lastPct;

	float tempoChange;
	float emergencyAdj = 0;
	float newcee = cTempo; // workspace var. for cTempo

	// IMPORTANT!
	// If you plan to tweak these values, make sure you're using a release build
	// OUTSIDE THE DEBUGGER to test it!  The Visual Studio debugger can really cause
	// erratic behavior in the audio buffers, and makes the timestretcher seem a
	// lot more inconsistent than it really is.

	// We have two factors.
	//   * Distance from nominal buffer status (50% full)
	//   * The change from previous update to this update.

	// Prediction based on the buffer change:
	// (linear seems to work better here)

	tempoChange = pctChange * 0.75f;

	if (statusPct * tempoChange < 0.0f)
		// only apply tempo change if it is in synch with the buffer status.
		// In other words, if the buffer is high (over 0%), and is decreasing,
		// ignore it.  It'll just muck things up.

		tempoChange = 0;

	// Sudden spikes in framerate can cause the nominal buffer status
	// to go critical, in which case we have to enact an emergency
	// stretch. The following cubic formulas do that.  Values near
	// the extremeites give much larger results than those near 0.
	// And the value is added only this time, and does not accumulate.
	// (otherwise a large value like this would cause problems down the road)

	// Constants:
	// Weight - weights the statusPct's "emergency" consideration.
	//   higher values here will make the buffer perform more drastic
	//   compensations at the outer edges of the buffer (at -75 or +75%
	//   or beyond, for example).

	// Range - scales the adjustment to the given range (more or less).
	//   The actual range is dependent on the weight used, so if you increase
	//   Weight you'll usually want to decrease Range somewhat to compensate.

	// Prediction based on the buffer fill status:

	float statusWeight = 2.99f;
	float statusRange = 0.068f;

	// "non-emergency" deadzone:  In this area stretching will be strongly discouraged.
	// Note: due tot he nature of timestretch latency, it's always a wee bit harder to
	// cope with low fps (underruns) than it is high fps (overruns).  So to help out a
	// little, the low-end portions of this check are less forgiving than the high-sides.

	if (cTempo < 0.965f || cTempo > 1.060f || pctChange < -0.38f || pctChange > 0.54f || statusPct < -0.32f || statusPct > 0.39f || eTempo < 0.89f || eTempo > 1.19f)
		emergencyAdj = std::pow(statusPct * statusWeight, 3.0f) * statusRange;

	// Smooth things out by factoring our previous adjustment into this one.
	// It helps make the system 'feel' a little smarter by  giving it at least
	// one packet worth of history to help work off of:

	emergencyAdj = (emergencyAdj * 0.75f) + (lastEmergencyAdj * 0.25f);

	lastEmergencyAdj = emergencyAdj;
	lastPct = statusPct;

	// Accumulate a fraction of the tempo change into the tempo itself.
	// This helps the system run "smarter" to games that run consistently
	// fast or slow by altering the base tempo to something closer to the
	// game's active speed.  In tests most games normalize within 2 seconds
	// at 100ms latency, which is pretty good (larger buffers normalize even
	// quicker).

	newcee += newcee * (tempoChange + emergencyAdj) * 0.03f;

	// Apply tempoChange as a scale of cTempo.  That way the effect is proportional
	// to the current tempo.  (otherwise tempos rate of change at the extremes would
	// be too drastic)

	float newTempo = newcee + (emergencyAdj * cTempo);

	// ... and as a final optimization, only stretch if the new tempo is outside
	// a nominal threshold.  Keep this threshold check small, because it could
	// cause some serious side effects otherwise. (enlarging the cTempo check above
	// is usually better/safer)
	if (newTempo < 0.970f || newTempo > 1.045f)
	{
		cTempo = newcee;

		if (newTempo < 0.10f)
			newTempo = 0.10f;
		else if (newTempo > 10.0f)
			newTempo = 10.0f;

		if (cTempo < 0.15f)
			cTempo = 0.15f;
		else if (cTempo > 7.5f)
			cTempo = 7.5f;

		pSoundTouch->setTempo(eTempo = newTempo);
		++ts_stats_stretchblocks;

		/*ConLog(" * SPU2: [Nominal %d%%] [Emergency: %d%%] (baseTempo: %d%% ) (newTempo: %d%%) (buffer: %d%%)\n",
			//(relation < 0.0) ? "Normalize" : "",
			(int)(tempoChange * 100.0 * 0.03),
			(int)(emergencyAdj * 100.0),
			(int)(cTempo * 100.0),
			(int)(newTempo * 100.0),
			(int)(statusPct * 100.0)
		);*/
	}
	else
	{
		// Nominal operation -- turn off stretching.
		// note: eTempo 'slides' toward 1.0 for smoother audio and better
		// protection against spikes.
		if (!fEqual(cTempo, 1.0f))
		{
			cTempo = 1.0f;
			eTempo = (1.0f + eTempo) * 0.5f;
			pSoundTouch->setTempo(eTempo);
		}
		else
		{
			if (!fEqual(eTempo, cTempo))
				pSoundTouch->setTempo(eTempo = cTempo);
			++ts_stats_normalblocks;
		}
	}
}

void SndBuffer::timeStretchUnderrun()
{
	// timeStretcher failed it's job.  We need to slow down the audio some.

	cTempo -= cTempo * 0.12f;
	eTempo -= eTempo * 0.30f;
	if (eTempo < 0.1f)
		eTempo = 0.1f;
	pSoundTouch->setTempo(eTempo);
}

int32_t SndBuffer::timeStretchOverrun()
{
	// If we overran it means the timestretcher failed.  We need to speed
	// up audio playback.
	cTempo += cTempo * 0.12f;
	eTempo += eTempo * 0.40f;
	if (eTempo > 7.5f)
		eTempo = 7.5f;
	pSoundTouch->setTempo(eTempo);

	// Throw out just a little bit (two packets worth) to help
	// give the TS some room to work:

	return SndOutPacketSize * 2;
}

static void CvtPacketToFloat(StereoOut32 *srcdest)
{
	StereoOutFloat *dest = reinterpret_cast<StereoOutFloat *>(srcdest);
	const StereoOut32 *src = srcdest;
	for (int i = 0; i < SndOutPacketSize; ++i, ++dest, ++src)
		*dest = static_cast<StereoOutFloat>(*src);
}

// Parameter note: Size should always be a multiple of 128, thanks!
static void CvtPacketToInt(StereoOut32 *srcdest, uint32_t size)
{
	//jASSUME( (size & 127) == 0 );

	const StereoOutFloat *src = reinterpret_cast<StereoOutFloat *>(srcdest);
	StereoOut32 *dest = srcdest;

	for (uint32_t i = 0; i < size; ++i, ++dest, ++src)
		*dest = static_cast<StereoOut32>(*src);
}

void SndBuffer::timeStretchWrite()
{
	bool progress = false;

	// data prediction helps keep the tempo adjustments more accurate.
	// The timestretcher returns packets in belated "clump" form.
	// Meaning that most of the time we'll get nothing back, and then
	// suddenly we'll get several chunks back at once.  Thus we use
	// data prediction to make the timestretcher more responsive.

	PredictDataWrite(SndOutPacketSize / eTempo);
	CvtPacketToFloat(sndTempBuffer.get());

	pSoundTouch->putSamples(reinterpret_cast<float *>(sndTempBuffer.get()), SndOutPacketSize);

	int tempProgress;
	while (tempProgress = pSoundTouch->receiveSamples(reinterpret_cast<float *>(sndTempBuffer.get()), SndOutPacketSize), !!tempProgress)
	{
		// Hint: It's assumed that pSoundTouch will return chunks of 128 bytes (it always does as
		// long as the SSE optimizations are enabled), which means we can do our own SSE opts here.

		CvtPacketToInt(sndTempBuffer.get(), tempProgress);
		_WriteSamples(sndTempBuffer.get(), tempProgress);
		progress = true;
	}

	UpdateTempoChange();

	//TODO
	//if( MsgOverruns() )
	{
		if(progress)
		{
			if (++ts_stats_logcounter > 300)
			{
				ts_stats_logcounter = 0;
				printf(" * SPU2 > Timestretch Stats > %d%% of packets stretched.\n", (ts_stats_stretchblocks * 100) / (ts_stats_normalblocks + ts_stats_stretchblocks));
				ts_stats_normalblocks = ts_stats_stretchblocks = 0;
			}
		}
	}
}

void SndBuffer::soundtouchInit()
{
	pSoundTouch.reset(new soundtouch::SoundTouch());
	pSoundTouch->setSampleRate(SampleRate);
	pSoundTouch->setChannels(2);

	pSoundTouch->setSetting(soundtouch::SETTING_USE_QUICKSEEK, 0);
	pSoundTouch->setSetting(soundtouch::SETTING_USE_AA_FILTER, 0);

	pSoundTouch->setTempo(1);

	// some timestretch management vars:

	cTempo = eTempo = 1.0;
	lastPct = lastEmergencyAdj = 0;

	// just freeze tempo changes for a while at startup.
	// the driver buffers are bogus anyway.
	freezeTempo = 16;
	m_predictData = 0;
}