/*
 * Tuxánci 2 - A first person shooter
 * Copyright (C) 2007-2011  Tuxánci Development Team
 * Copyright (C) 2025-2026  Connor Thomson
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

#ifdef ENABLE_AUDIO

#include <libopenmpt/libopenmpt.h>
#include "ta_sdl.h"
#include "ta_alc.h"
#include "ta_al.h"
#include "files.h"
#include "main.h"
#include "ta_openmpt.h"

#define TA_AUDIO_FREQUENCY_HZ   44100
#define TA_AUDIO_BUFFER_AMOUNT  4
#define TA_AUDIO_MIXBUFFER_SAMPLES 2048

ALCdevice *ta_audio_device;
ALCcontext *ta_audio_context;
ALuint ta_audio_source;
ALuint ta_audio_buffers[TA_AUDIO_BUFFER_AMOUNT];
int16_t ta_audio_mixbuffer[TA_AUDIO_MIXBUFFER_SAMPLES];

static openmpt_module *ta_audio_module;

static void ta_audio_decode(void) {
    size_t frame_count = TA_AUDIO_MIXBUFFER_SAMPLES / 2;
    size_t rendered = openmpt_module_read_interleaved_stereo(
        ta_audio_module,
        TA_AUDIO_FREQUENCY_HZ,
        frame_count,
        ta_audio_mixbuffer
    );

    if (rendered < frame_count) {
        SDL_memset(
            ta_audio_mixbuffer + rendered * 2,
            0,
            (frame_count - rendered) * 2 * sizeof(*ta_audio_mixbuffer)
        );
    }
}

void ta_audio_init(void) {
    ta_audio_device = ta_alc_open_device();

    ALCint attributes[] = {
        ALC_FREQUENCY, TA_AUDIO_FREQUENCY_HZ,
        0
    };
    ta_audio_context = ta_alc_create_context(ta_audio_device, attributes);
    ta_alc_make_context_current(ta_audio_context);

    ta_audio_module = ta_openmpt_load_module(file_data_music_theme_it_start, file_data_music_theme_it_size);

    ta_openmpt_set_module_repeat_count(ta_audio_module, -1);

    alGenSources(1, &ta_audio_source);
    
    alGenBuffers(TA_AUDIO_BUFFER_AMOUNT, ta_audio_buffers);

    for (int index = 0; index < TA_AUDIO_BUFFER_AMOUNT; index++) {
        ta_audio_decode();
        alBufferData(
            ta_audio_buffers[index],
            AL_FORMAT_STEREO16,
            ta_audio_mixbuffer,
            sizeof(ta_audio_mixbuffer),
            TA_AUDIO_FREQUENCY_HZ
        );
    }

    alSourceQueueBuffers(
        ta_audio_source,
        TA_AUDIO_BUFFER_AMOUNT,
        ta_audio_buffers
    );
    alSourcePlay(ta_audio_source);
}

void ta_audio_update(void) {
    ALint processed = 0;
    alGetSourcei(ta_audio_source, AL_BUFFERS_PROCESSED, &processed);

    while (processed--) {
        ALuint buffer;
        alSourceUnqueueBuffers(ta_audio_source, 1, &buffer);

        ta_audio_decode();

        alBufferData(buffer, AL_FORMAT_STEREO16, ta_audio_mixbuffer, sizeof(ta_audio_mixbuffer), TA_AUDIO_FREQUENCY_HZ);
        alSourceQueueBuffers(ta_audio_source, 1, &buffer);
    }
}

void ta_audio_destroy(void) {
    alSourceStop(ta_audio_source);
    alDeleteSources(1, &ta_audio_source);
    alDeleteBuffers(TA_AUDIO_BUFFER_AMOUNT, ta_audio_buffers);
    if (!ta_audio_module) {
        openmpt_module_destroy(ta_audio_module);
        ta_audio_module = NULL;
    }
    ta_alc_make_context_current(NULL);
    alcDestroyContext(ta_audio_context);
    ta_alc_close_device(ta_audio_device);
}

#endif // ENABLE_AUDIO