/*
voice.c - voice chat implementation
Copyright (C) 2022 Velaron
Copyright (C) 2022 SNMetamorph

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.
*/

#define CUSTOM_MODES 1 // required to correctly link with Opus Custom
#include <opus_custom.h>
#include "common.h"
#include "client.h"
#include "voice.h"

voice_state_t voice = { 0 };

CVAR_DEFINE_AUTO( voice_enable, "1", FCVAR_PRIVILEGED|FCVAR_ARCHIVE, "enable voice chat" );
CVAR_DEFINE_AUTO( voice_loopback, "0", FCVAR_PRIVILEGED, "loopback voice back to the speaker" );
CVAR_DEFINE_AUTO( voice_scale, "1.0", FCVAR_PRIVILEGED|FCVAR_ARCHIVE, "incoming voice volume scale" );
CVAR_DEFINE_AUTO( voice_transmit_scale, "1.0", FCVAR_PRIVILEGED|FCVAR_ARCHIVE, "outcoming voice volume scale" );
CVAR_DEFINE_AUTO( voice_avggain, "0.5", FCVAR_PRIVILEGED|FCVAR_ARCHIVE, "automatic voice gain control (average)" );
CVAR_DEFINE_AUTO( voice_maxgain, "5.0", FCVAR_PRIVILEGED|FCVAR_ARCHIVE, "automatic voice gain control (maximum)" );
CVAR_DEFINE_AUTO( voice_inputfromfile, "0", FCVAR_PRIVILEGED, "input voice from voice_input.wav" );

static void Voice_ApplyGainAdjust( int16_t *samples, int count, float scale );

// in case user enabled voice after connection
// can't keep in `voice` struct because it gets zeroed on shutdown
static string voice_codec_init;
static int voice_quality_init;

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

	OPUS INTEGRATION

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

static qboolean Voice_InitCustomMode( void )
{
	int err = 0;

	voice.width = sizeof( opus_int16 );
	voice.samplerate = VOICE_OPUS_CUSTOM_SAMPLERATE;
	voice.frame_size = VOICE_OPUS_CUSTOM_FRAME_SIZE;

	voice.custom_mode = opus_custom_mode_create( SOUND_44k, voice.frame_size, &err );

	if( !voice.custom_mode )
	{
		Con_Printf( S_ERROR "Can't create Opus Custom mode: %s\n", opus_strerror( err ));
		return false;
	}

	return true;
}

/*
=========================
Voice_InitOpusDecoder

=========================
*/
static qboolean Voice_InitOpusDecoder( void )
{
	int err = 0;

	for( int i = 0; i < cl.maxclients; i++ )
	{
		voice.decoders[i] = opus_custom_decoder_create( voice.custom_mode, VOICE_PCM_CHANNELS, &err );

		if( !voice.decoders[i] )
		{
			Con_Printf( S_ERROR "Can't create Opus decoder for %i: %s\n", i, opus_strerror( err ));
			return false;
		}
	}

	return true;
}

/*
=========================
Voice_InitOpusEncoder

=========================
*/
static qboolean Voice_InitOpusEncoder( int quality )
{
	int err = 0;

	voice.encoder = opus_custom_encoder_create( voice.custom_mode, VOICE_PCM_CHANNELS, &err );
	if( !voice.encoder )
	{
		Con_Printf( S_ERROR "Can't create Opus encoder: %s\n", opus_strerror( err ));
		return false;
	}

	switch( quality )
	{
	case 1: // 6 kbps
		opus_custom_encoder_ctl( voice.encoder, OPUS_SET_BITRATE( 6000 ));
		break;
	case 2: // 12 kbps
		opus_custom_encoder_ctl( voice.encoder, OPUS_SET_BITRATE( 12000 ));
		break;
	case 4: // 64 kbps
		opus_custom_encoder_ctl( voice.encoder, OPUS_SET_BITRATE( 64000 ));
		break;
	case 5: // 96 kbps
		opus_custom_encoder_ctl( voice.encoder, OPUS_SET_BITRATE( 96000 ));
		break;
	default: // 36 kbps
		opus_custom_encoder_ctl( voice.encoder, OPUS_SET_BITRATE( 36000 ));
		break;
	}

	return true;
}

/*
=========================
Voice_ShutdownOpusDecoder

=========================
*/
static void Voice_ShutdownOpusDecoder( void )
{
	for( int i = 0; i < MAX_CLIENTS; i++ )
	{
		if( !voice.decoders[i] )
			continue;

		opus_custom_decoder_destroy( voice.decoders[i] );
		voice.decoders[i] = NULL;
	}
}

/*
=========================
Voice_ShutdownOpusEncoder

=========================
*/
static void Voice_ShutdownOpusEncoder( void )
{
	if( voice.encoder )
	{
		opus_custom_encoder_destroy( voice.encoder );
		voice.encoder = NULL;
	}
}

static void Voice_ShutdownCustomMode( void )
{
	if( voice.custom_mode )
	{
		opus_custom_mode_destroy( voice.custom_mode );
		voice.custom_mode = NULL;
	}
}

/*
=========================
Voice_GetOpusCompressedData

=========================
*/
static uint Voice_GetOpusCompressedData( byte *out, uint maxsize, uint *frames )
{
	uint ofs = 0, size = 0;
	uint frame_size_bytes = voice.frame_size * voice.width;

	if( voice.input_file )
	{
		uint numbytes;
		double updateInterval, curtime = Sys_DoubleTime();

		updateInterval = curtime - voice.start_time;
		voice.start_time = curtime;

		numbytes = updateInterval * voice.samplerate * voice.width * VOICE_PCM_CHANNELS;
		numbytes = Q_min( numbytes, voice.input_file->size - voice.input_file_pos );
		numbytes = Q_min( numbytes, sizeof( voice.input_buffer ) - voice.input_buffer_pos );

		memcpy( voice.input_buffer + voice.input_buffer_pos, voice.input_file->buffer + voice.input_file_pos, numbytes );
		voice.input_buffer_pos += numbytes;
		voice.input_file_pos += numbytes;
	}

	if( !voice.input_file )
		VoiceCapture_Lock( true );

	for( ofs = 0; voice.input_buffer_pos - ofs >= frame_size_bytes && ofs <= voice.input_buffer_pos; ofs += frame_size_bytes )
	{
		int bytes;

#if 1
		if( !voice.input_file )
		{
			// adjust gain before encoding, but only for input from voice
			Voice_ApplyGainAdjust((opus_int16*)(voice.input_buffer + ofs), voice.frame_size, voice_transmit_scale.value);
		}
#endif

		bytes = opus_custom_encode( voice.encoder, (const opus_int16 *)( voice.input_buffer + ofs ),
			voice.frame_size, out + size + sizeof( uint16_t ), maxsize );

		if( bytes > 0 )
		{
			// write compressed frame size
			*((uint16_t *)&out[size]) = bytes;

			size += bytes + sizeof( uint16_t );
			maxsize -= bytes + sizeof( uint16_t );

			(*frames)++;
		}
		else
		{
			Con_Printf( S_ERROR "%s: failed to encode frame: %s\n", __func__, opus_strerror( bytes ));
		}
	}

	// did we compress anything? update counters
	if( ofs )
	{
		fs_offset_t remaining = voice.input_buffer_pos - ofs;

		// move remaining samples to the beginning of buffer
		memmove( voice.input_buffer, voice.input_buffer + ofs, remaining );

		voice.input_buffer_pos = remaining;
	}

	if( !voice.input_file )
		VoiceCapture_Lock( false );

	return size;
}

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

	VOICE CHAT INTEGRATION

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

/*
=========================
Voice_ApplyGainAdjust

=========================
*/
static void Voice_ApplyGainAdjust( int16_t *samples, int count, float scale )
{
	float gain, modifiedMax;
	int average, blockOffset = 0;

	for( ;; )
	{
		int i, localMax = 0, localSum = 0;
		int blockSize = Q_min( count - ( blockOffset + voice.autogain.block_size ), voice.autogain.block_size );

		if( blockSize < 1 )
			break;

		for( i = 0; i < blockSize; ++i )
		{
			int sample = samples[blockOffset + i];
			int absSample = abs( sample );

			if( absSample > localMax )
				localMax = absSample;

			localSum += absSample;
			gain = voice.autogain.current_gain + i * voice.autogain.gain_multiplier;
			samples[blockOffset + i] = bound( SHRT_MIN, (int)( sample * gain ), SHRT_MAX );
		}

		if( blockOffset % voice.autogain.block_size == 0 )
		{
			average = localSum / blockSize;
			modifiedMax = average + ( localMax - average ) * voice_avggain.value;

			voice.autogain.current_gain = voice.autogain.next_gain * scale;
			voice.autogain.next_gain = Q_min( (float)SHRT_MAX / modifiedMax, voice_maxgain.value ) * scale;
			voice.autogain.gain_multiplier = ( voice.autogain.next_gain - voice.autogain.current_gain ) / ( blockSize - 1 );
		}
		blockOffset += blockSize;
	}
}

/*
=========================
Voice_Status

Notify user dll aboit voice transmission
=========================
*/
static void Voice_Status( int entindex, qboolean bTalking )
{
	if( cls.state == ca_active && clgame.dllFuncs.pfnVoiceStatus )
		clgame.dllFuncs.pfnVoiceStatus( entindex, bTalking );
}

/*
=========================
Voice_StatusTimeout

Waits few milliseconds and if there was no
voice transmission, sends notification
=========================
*/
static void Voice_StatusTimeout( voice_status_t *status, int entindex, double frametime )
{
	if( status->talking_ack )
	{
		status->talking_timeout += frametime;
		if( status->talking_timeout > 0.2 )
		{
			status->talking_ack = false;
			Voice_Status( entindex, false );
		}
	}
}

/*
=========================
Voice_StatusAck

Sends notification to user dll and
zeroes timeouts for this client
=========================
*/
void Voice_StatusAck( voice_status_t *status, int playerIndex )
{
	if( !status->talking_ack )
		Voice_Status( playerIndex, true );

	status->talking_ack = true;
	status->talking_timeout = 0.0;
}

/*
=========================
Voice_IsRecording

=========================
*/
qboolean Voice_IsRecording( void )
{
	return voice.is_recording;
}

/*
=========================
Voice_RecordStop

=========================
*/
void Voice_RecordStop( void )
{
	if( voice.input_file )
	{
		FS_FreeSound( voice.input_file );
		voice.input_file = NULL;
	}

	VoiceCapture_Activate( false );
	voice.is_recording = false;

	Voice_Status( VOICE_LOCALCLIENT_INDEX, false );

	voice.input_buffer_pos = 0;
	memset( voice.input_buffer, 0, sizeof( voice.input_buffer ));
}

/*
=========================
Voice_RecordStart

=========================
*/
void Voice_RecordStart( void )
{
	Voice_RecordStop();

	if( !voice.initialized )
		return;

	if( voice_inputfromfile.value )
	{
		voice.input_file = FS_LoadSound( "voice_input.wav", NULL, 0 );

		if( voice.input_file )
		{
			Sound_Process( &voice.input_file, voice.samplerate, voice.width, VOICE_PCM_CHANNELS, SOUND_RESAMPLE );
			voice.input_file_pos = 0;

			voice.start_time = Sys_DoubleTime();
			voice.is_recording = true;
		}
		else
		{
			FS_FreeSound( voice.input_file );
			voice.input_file = NULL;
		}
	}

	if( !Voice_IsRecording( ) && voice.device_opened )
		voice.is_recording = VoiceCapture_Activate( true );

	if( Voice_IsRecording() )
		Voice_Status( VOICE_LOCALCLIENT_INDEX, true );
}

/*
=========================
Voice_Disconnect

We're disconnected from server
stop recording and notify user dlls
=========================
*/
void Voice_Disconnect( void )
{
	int i;

	Voice_RecordStop();

	if( voice.local.talking_ack )
	{
		Voice_Status( VOICE_LOOPBACK_INDEX, false );
		voice.local.talking_ack = false;
	}

	for( i = 0; i < MAX_CLIENTS; i++ )
	{
		if( voice.players_status[i].talking_ack )
		{
			Voice_Status( i, false );
			voice.players_status[i].talking_ack = false;
		}
	}

	VoiceCapture_Shutdown();
	voice.device_opened = false;
}

/*
=========================
Voice_StartChannel

Feed the decoded data to engine sound subsystem
=========================
*/
static void Voice_StartChannel( uint samples, byte *data, int entnum )
{
	SND_ForceInitMouth( entnum );
	S_RawEntSamples( entnum, samples, voice.samplerate, voice.width, VOICE_PCM_CHANNELS, data, bound( 0, 255 * voice_scale.value, 255 ));
}

/*
=========================
Voice_AddIncomingData

Received encoded voice data, decode it
=========================
*/
void Voice_AddIncomingData( int ent, const byte *data, uint size, uint frames )
{
	const int playernum = ent - 1;
	int samples = 0;
	int ofs = 0;

	if( playernum < 0 || playernum >= cl.maxclients || !voice.decoders[playernum] )
		return;

	// decode frame by frame
	for( ;; )
	{
		int frame_samples;
		uint16_t compressed_size;

		// no compressed size mark
		if( ofs + sizeof( uint16_t ) > size )
			break;

		compressed_size = *(const uint16_t *)(data + ofs);
		ofs += sizeof( uint16_t );

		// no frame data
		if( ofs + compressed_size > size )
			break;

		frame_samples = opus_custom_decode( voice.decoders[playernum], data + ofs, compressed_size,
			(opus_int16*)voice.decompress_buffer + samples, voice.frame_size );

		ofs += compressed_size;
		samples += frame_samples;
	}

	if( samples > 0 )
		Voice_StartChannel( samples, voice.decompress_buffer, ent );
}

/*
=========================
CL_AddVoiceToDatagram

Encode our voice data and send it to server
=========================
*/
void CL_AddVoiceToDatagram( void )
{
	uint size, frames = 0;

	if( cls.state != ca_active || !Voice_IsRecording() || !voice.encoder )
		return;
	
	size = Voice_GetOpusCompressedData( voice.compress_buffer, sizeof( voice.compress_buffer ), &frames );

	if( size > 0 && MSG_GetNumBytesLeft( &cls.datagram ) >= size + 32 )
	{
		MSG_BeginClientCmd( &cls.datagram, clc_voicedata );
		MSG_WriteByte( &cls.datagram, voice_loopback.value != 0 );
		MSG_WriteByte( &cls.datagram, frames );
		MSG_WriteShort( &cls.datagram, size );
		MSG_WriteBytes( &cls.datagram, voice.compress_buffer, size );
	}
}

/*
=========================
Voice_RegisterCvars

Register voice related cvars and commands
=========================
*/
void Voice_RegisterCvars( void )
{
	Cvar_RegisterVariable( &voice_enable );
	Cvar_RegisterVariable( &voice_loopback );
	Cvar_RegisterVariable( &voice_scale );
	Cvar_RegisterVariable( &voice_transmit_scale );
	Cvar_RegisterVariable( &voice_avggain );
	Cvar_RegisterVariable( &voice_maxgain );
	Cvar_RegisterVariable( &voice_inputfromfile );
}

/*
=========================
Voice_Shutdown

Completely shutdown the voice subsystem
=========================
*/
static void Voice_Shutdown( void )
{
	int i;

	Voice_RecordStop();
	Voice_ShutdownOpusDecoder();
	Voice_ShutdownOpusEncoder();
	Voice_ShutdownCustomMode();
	VoiceCapture_Shutdown();

	if( voice.local.talking_ack )
		Voice_Status( VOICE_LOOPBACK_INDEX, false );

	for( i = 0; i < MAX_CLIENTS; i++ )
	{
		if( voice.players_status[i].talking_ack )
			Voice_Status( i, false );
	}

	memset( &voice, 0, sizeof( voice ));
}

/*
=========================
Voice_Idle

Run timeout for all clients
=========================
*/
void Voice_Idle( double frametime )
{
	int i;

	if( FBitSet( voice_enable.flags, FCVAR_CHANGED ))
	{
		ClearBits( voice_enable.flags, FCVAR_CHANGED );

		if( voice_enable.value )
		{
			if( cls.state == ca_active && COM_CheckString( voice_codec_init ) && voice_quality_init != 0 )
				Voice_Init( voice_codec_init, voice_quality_init, false );
		}
		else
			Voice_Shutdown();
	}

	// update local player status first
	Voice_StatusTimeout( &voice.local, VOICE_LOOPBACK_INDEX, frametime );

	for( i = 0; i < MAX_CLIENTS; i++ )
		Voice_StatusTimeout( &voice.players_status[i], i, frametime );
}

/*
=========================
Voice_Init

Initialize the voice subsystem
=========================
*/
qboolean Voice_Init( const char *pszCodecName, int quality, qboolean preinit )
{
	if( Q_strcmp( pszCodecName, VOICE_OPUS_CUSTOM_CODEC ))
	{
		if( COM_CheckStringEmpty( pszCodecName ))
			Con_Printf( S_ERROR "Server requested unsupported codec: %s\n", pszCodecName );

		// reset saved codec name, we won't enable voice for this connection
		voice_codec_init[0] = 0;
		voice_quality_init = 0;
		return false;
	}

	Q_strncpy( voice_codec_init, pszCodecName, sizeof( voice_codec_init ));
	voice_quality_init = quality;

	if( !voice_enable.value )
		return false;

	// reinitialize only if codec parameters are different
	if( Q_strcmp( pszCodecName, voice.codec ) || voice.quality != quality )
	{
		Voice_Shutdown();
		voice.autogain.block_size = 128;

		if( !Voice_InitCustomMode( ))
		{
			// no reason to init encoder and open audio device
			// if we can't hear other players
			Voice_Shutdown();
			return false;
		}

		// we can hear others players, so it's fine to fail now
		voice.initialized = true;
		Q_strncpy( voice.codec, pszCodecName, sizeof( voice.codec ));

		if( !Voice_InitOpusEncoder( quality ))
		{
			Con_Printf( S_WARN "Other players will not be able to hear you.\n" );
			return false;
		}

		voice.quality = quality;
	}

	if( !preinit )
	{
		Voice_ShutdownOpusDecoder();
		if( !Voice_InitOpusDecoder())
		{
			// no reason to init encoder and open audio device
			// if we can't hear other players
			Con_Printf( S_ERROR "Can't create decoders, voice chat is disabled.\n" );
			Voice_Shutdown();
			return false;
		}

		voice.device_opened = VoiceCapture_Init();

		if( !voice.device_opened )
			Con_Printf( S_WARN "No microphone is available.\n" );
	}

	return true;
}