//========= Copyright (c) 1996-2005, Valve Corporation, All rights reserved. ============//
//
// Purpose: 
//
// $NoKeywords: $
//=============================================================================//


#include "audio_pch.h"
#include "snd_mp3_source.h"
#include "vaudio/ivaudio.h"

// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"

extern IVAudio *vaudio;

static const int MP3_BUFFER_SIZE = 16384;

//-----------------------------------------------------------------------------
// Purpose: Mixer for ADPCM encoded audio
//-----------------------------------------------------------------------------
class CAudioMixerWaveMP3 : public CAudioMixerWave, public IAudioStreamEvent
{
public:
	CAudioMixerWaveMP3( IWaveData *data );
	~CAudioMixerWaveMP3( void );
	
	virtual void Mix( channel_t *pChannel, void *pData, int outputOffset, int inputOffset, fixedint fracRate, int outCount, int timecompress );
	virtual int	 GetOutputData( void **pData, int sampleCount, char copyBuf[AUDIOSOURCE_COPYBUF_SIZE] );

	// need to override this to fixup blocks
	// UNDONE: This doesn't quite work with MP3 - we need a MP3 position, not a sample position
	void SetSampleStart( int newPosition );

	int GetPositionForSave() { return m_pStream->GetPosition(); }
	void SetPositionFromSaved(int position) { m_pStream->SetPosition(position); }

	// IAudioStreamEvent
	virtual int StreamRequestData( void *pBuffer, int bytesRequested, int offset );

	virtual void SetStartupDelaySamples( int delaySamples );
	virtual int GetMixSampleSize() { return CalcSampleSize( 16, m_channelCount ); }

	bool IsValid() { return m_pStream != NULL; }

	virtual int GetStreamOutputRate() { return m_pStream->GetOutputRate(); }

private:
	bool					DecodeBlock( void );
	void					GetID3HeaderOffset();


	IAudioStream			*m_pStream;
	char					m_samples[MP3_BUFFER_SIZE];
	int						m_sampleCount;
	int						m_samplePosition;
	int						m_channelCount;
	int						m_offset;
	int						m_delaySamples;
	int						m_headerOffset;
};


CAudioMixerWaveMP3::CAudioMixerWaveMP3( IWaveData *data ) : CAudioMixerWave( data ) 
{
	m_sampleCount = 0;
	m_samplePosition = 0;
	m_offset = 0;
	m_delaySamples = 0;
	m_headerOffset = 0;
	m_pStream = NULL;
	if ( vaudio )
		m_pStream = vaudio->CreateMP3StreamDecoder( static_cast<IAudioStreamEvent *>(this) );
	if ( m_pStream )
	{
		m_channelCount = m_pStream->GetOutputChannels();
		//Assert( m_pStream->GetOutputRate() == m_pData->Source().SampleRate() );
	}
}


CAudioMixerWaveMP3::~CAudioMixerWaveMP3( void )
{
	if ( m_pStream )
	{
		vaudio->DestroyMP3StreamDecoder( m_pStream );
		m_pStream = NULL;
	}
}


void CAudioMixerWaveMP3::Mix( channel_t *pChannel, void *pData, int outputOffset, int inputOffset, fixedint fracRate, int outCount, int timecompress )
{
	if ( m_channelCount == 1 )
	{
		Device_Mix16Mono( pChannel, (short *)pData, outputOffset, inputOffset, fracRate, outCount, timecompress );
	}
	else
	{
		Device_Mix16Stereo( pChannel, (short *)pData, outputOffset, inputOffset, fracRate, outCount, timecompress );
	}

}


// Some MP3 files are wrapped in ID3
void CAudioMixerWaveMP3::GetID3HeaderOffset()
{
	char copyBuf[AUDIOSOURCE_COPYBUF_SIZE];
	byte *pData;

	int bytesRead = m_pData->ReadSourceData( (void **)&pData, 0, 10, copyBuf );
	if ( bytesRead < 10 )
		return;

	m_headerOffset = 0;
	if (( pData[ 0 ] == 0x49 ) &&
		( pData[ 1 ] == 0x44 ) &&
		( pData[ 2 ] == 0x33 ) &&
		( pData[ 3 ] < 0xff ) &&
		( pData[ 4 ] < 0xff ) &&
		( pData[ 6 ] < 0x80 ) &&
		( pData[ 7 ] < 0x80 ) &&
		( pData[ 8 ] < 0x80 ) &&
		( pData[ 9 ] < 0x80 ) )
	{
		// this is in id3 file
		// compute the size of the wrapper and skip it
		m_headerOffset = 10 + ( pData[9] | (pData[8]<<7) | (pData[7]<<14) | (pData[6]<<21) );
   }
}

int CAudioMixerWaveMP3::StreamRequestData( void *pBuffer, int bytesRequested, int offset )
{
	if ( offset < 0 )
	{
		offset = m_offset;
	}
	else
	{
		m_offset = offset;
	}
	// read the data out of the source
	int totalBytesRead = 0;

	if ( offset == 0 )
	{
		// top of file, check for ID3 wrapper
		GetID3HeaderOffset();
	}

	offset += m_headerOffset; // skip any id3 header/wrapper
	
	while ( bytesRequested > 0 )
	{
		char *pOutputBuffer = (char *)pBuffer;
		pOutputBuffer += totalBytesRead;

		void *pData = NULL;
		int bytesRead = m_pData->ReadSourceData( &pData, offset + totalBytesRead, bytesRequested, pOutputBuffer );
		
		if ( !bytesRead )
			break;
		if ( bytesRead > bytesRequested )
		{
			bytesRead = bytesRequested;
		}
		// if the source is buffering it, copy it to the MP3 decomp buffer
		if ( pData != pOutputBuffer )
		{
			memcpy( pOutputBuffer, pData, bytesRead );
		}
		totalBytesRead += bytesRead;
		bytesRequested -= bytesRead;
	}

	m_offset += totalBytesRead;
	return totalBytesRead;
}

bool CAudioMixerWaveMP3::DecodeBlock()
{
	m_sampleCount = m_pStream->Decode( m_samples, sizeof(m_samples) );
	m_samplePosition = 0;
	return m_sampleCount > 0;
}

//-----------------------------------------------------------------------------
// Purpose: Read existing buffer or decompress a new block when necessary
// Input  : **pData - output data pointer
//			sampleCount - number of samples (or pairs)
// Output : int - available samples (zero to stop decoding)
//-----------------------------------------------------------------------------
int CAudioMixerWaveMP3::GetOutputData( void **pData, int sampleCount, char copyBuf[AUDIOSOURCE_COPYBUF_SIZE] )
{
	if ( m_samplePosition >= m_sampleCount )
	{
		if ( !DecodeBlock() )
			return 0;
	}

	if ( m_samplePosition < m_sampleCount )
	{
		int sampleSize = m_channelCount * 2;
		*pData = (void *)(m_samples + m_samplePosition);
		int available = m_sampleCount - m_samplePosition;
		int bytesRequired = sampleCount * sampleSize;
		if ( available > bytesRequired )
			available = bytesRequired;

		m_samplePosition += available;
		
		int samples_loaded = available / sampleSize;

		// update count of max samples loaded in CAudioMixerWave

		CAudioMixerWave::m_sample_max_loaded += samples_loaded;

		// update index of last sample loaded

		CAudioMixerWave::m_sample_loaded_index += samples_loaded;

		return samples_loaded;
	}

	return 0;
}



//-----------------------------------------------------------------------------
// Purpose: Seek to a new position in the file
//			NOTE: In most cases, only call this once, and call it before playing
//			any data.
// Input  : newPosition - new position in the sample clocks of this sample
//-----------------------------------------------------------------------------
void CAudioMixerWaveMP3::SetSampleStart( int newPosition )
{
	// UNDONE: Implement this?
}

//-----------------------------------------------------------------------------
// Purpose: 
// Input  : delaySamples - 
//-----------------------------------------------------------------------------
void CAudioMixerWaveMP3::SetStartupDelaySamples( int delaySamples )
{
	m_delaySamples = delaySamples;
}

//-----------------------------------------------------------------------------
// Purpose: Abstract factory function for MP3 mixers
// Input  : *data - wave data access object
//			channels - 
// Output : CAudioMixer
//-----------------------------------------------------------------------------
CAudioMixer *CreateMP3Mixer( IWaveData *data, int *pSampleRate )
{
	CAudioMixerWaveMP3 *pMixer = new CAudioMixerWaveMP3( data );
	if ( pMixer->IsValid() )
	{
		// pass the sample rate back just in time to save parsing the MP3 file twice to get sample rate
		if ( pSampleRate )
		{
			*pSampleRate = pMixer->GetStreamOutputRate();
		}
		return pMixer;
	}

	delete pMixer;
	return NULL;
}