//###########################################################################
//
//	L4AUDEFX.cpp -- OpenAL EFX bridge (task #50, AUDIO_FIDELITY F9/F11).
//	See L4AUDEFX.h for the fidelity rationale.
//
//###########################################################################
#include <cstdlib>
#include "mungal4.h"
#pragma hdrstop

#include "l4audefx.h"
#include "openal/alc.h"
#include "openal/efx.h"

#ifndef AL_EFFECT_EAXREVERB
#define AL_EFFECT_EAXREVERB 0x8000	// newer efx.h constant; OpenAL Soft supports it
#endif

namespace
{
	bool s_available = false;
	ALuint s_reverbSlot = 0;
	ALuint s_reverbEffect = 0;
	ALuint s_scratchFilter = 0;

	LPALGENEFFECTS               p_alGenEffects = 0;
	LPALEFFECTI                  p_alEffecti = 0;
	LPALEFFECTF                  p_alEffectf = 0;
	LPALGENAUXILIARYEFFECTSLOTS  p_alGenAuxiliaryEffectSlots = 0;
	LPALAUXILIARYEFFECTSLOTI     p_alAuxiliaryEffectSloti = 0;
	LPALAUXILIARYEFFECTSLOTF     p_alAuxiliaryEffectSlotf = 0;
	LPALGENFILTERS               p_alGenFilters = 0;
	LPALFILTERI                  p_alFilteri = 0;
	LPALFILTERF                  p_alFilterf = 0;
}

bool EFX_Available()
{
	return s_available;
}

bool EFX_Initialize(float global_reverb_scale)
{
	ALCcontext *context = alcGetCurrentContext();
	if (context == 0)
	{
		return false;
	}
	ALCdevice *device = alcGetContextsDevice(context);
	if (device == 0 || !alcIsExtensionPresent(device, "ALC_EXT_EFX"))
	{
		if (getenv("BT_AUDIO_LOG"))
			DEBUG_STREAM << "[audio] EFX: ALC_EXT_EFX NOT present -- filters/reverb inert\n" << std::flush;
		return false;
	}

	p_alGenEffects              = (LPALGENEFFECTS)alGetProcAddress("alGenEffects");
	p_alEffecti                 = (LPALEFFECTI)alGetProcAddress("alEffecti");
	p_alEffectf                 = (LPALEFFECTF)alGetProcAddress("alEffectf");
	p_alGenAuxiliaryEffectSlots = (LPALGENAUXILIARYEFFECTSLOTS)alGetProcAddress("alGenAuxiliaryEffectSlots");
	p_alAuxiliaryEffectSloti    = (LPALAUXILIARYEFFECTSLOTI)alGetProcAddress("alAuxiliaryEffectSloti");
	p_alAuxiliaryEffectSlotf    = (LPALAUXILIARYEFFECTSLOTF)alGetProcAddress("alAuxiliaryEffectSlotf");
	p_alGenFilters              = (LPALGENFILTERS)alGetProcAddress("alGenFilters");
	p_alFilteri                 = (LPALFILTERI)alGetProcAddress("alFilteri");
	p_alFilterf                 = (LPALFILTERF)alGetProcAddress("alFilterf");

	if (!p_alGenEffects || !p_alEffecti || !p_alEffectf
		|| !p_alGenAuxiliaryEffectSlots || !p_alAuxiliaryEffectSloti || !p_alAuxiliaryEffectSlotf
		|| !p_alGenFilters || !p_alFilteri || !p_alFilterf)
	{
		if (getenv("BT_AUDIO_LOG"))
			DEBUG_STREAM << "[audio] EFX: entry points missing -- filters/reverb inert\n" << std::flush;
		return false;
	}

	alGetError();
	p_alGenAuxiliaryEffectSlots(1, &s_reverbSlot);
	p_alGenEffects(1, &s_reverbEffect);
	if (alGetError() != AL_NO_ERROR)
	{
		return false;
	}

	// EAXReverb where available (OpenAL Soft: yes), plain reverb otherwise.
	p_alEffecti(s_reverbEffect, AL_EFFECT_TYPE, AL_EFFECT_EAXREVERB);
	if (alGetError() != AL_NO_ERROR)
	{
		p_alEffecti(s_reverbEffect, AL_EFFECT_TYPE, AL_EFFECT_REVERB);
	}
	p_alAuxiliaryEffectSloti(s_reverbSlot, AL_EFFECTSLOT_EFFECT, (ALint)s_reverbEffect);
	// The authentic wet level: the original sent CC91 = global_reverb_scale
	// (0.3 -> value 38) on every 3D channel; one global slot gain reproduces
	// the same uniform send.
	p_alAuxiliaryEffectSlotf(s_reverbSlot, AL_EFFECTSLOT_GAIN,
		(global_reverb_scale < 0.0f) ? 0.0f :
		(global_reverb_scale > 1.0f) ? 1.0f : global_reverb_scale);

	p_alGenFilters(1, &s_scratchFilter);
	p_alFilteri(s_scratchFilter, AL_FILTER_TYPE, AL_FILTER_LOWPASS);

	s_available = (alGetError() == AL_NO_ERROR);
	if (getenv("BT_AUDIO_LOG"))
		DEBUG_STREAM << "[audio] EFX: " << (s_available ? "READY" : "FAILED")
			<< " (reverb slot gain=" << global_reverb_scale << ")\n" << std::flush;
	return s_available;
}

void EFX_SetSourceLowpassGainHF(ALuint source, float gainhf)
{
	if (!s_available)
	{
		return;
	}
	if (gainhf < 0.001f) gainhf = 0.001f;
	if (gainhf > 1.0f)   gainhf = 1.0f;
	// filter params are COPIED at attach, so one scratch filter serves all
	p_alFilterf(s_scratchFilter, AL_LOWPASS_GAIN, 1.0f);
	p_alFilterf(s_scratchFilter, AL_LOWPASS_GAINHF, gainhf);
	alSourcei(source, AL_DIRECT_FILTER, (ALint)s_scratchFilter);
}

void EFX_AttachReverbSend(ALuint source)
{
	if (!s_available)
	{
		return;
	}
	alSource3i(source, AL_AUXILIARY_SEND_FILTER, (ALint)s_reverbSlot, 0, AL_FILTER_NULL);
}