#include "kknd.h"

/* =========================================================================
 * audio.c - Procedural sound effects via SDL audio queue (no asset files).
 * ========================================================================= */

static SDL_AudioDeviceID g_dev = 0;
static int g_audio_ok = 0;

int audio_init(void) {
    SDL_AudioSpec want, have;
    memset(&want, 0, sizeof want);
    want.freq = 22050;
    want.format = AUDIO_S16SYS;
    want.channels = 1;
    want.samples = 1024;
    g_dev = SDL_OpenAudioDevice(NULL, 0, &want, &have, 0);
    if (g_dev == 0) { return 0; }
    g_audio_ok = 1;
    SDL_PauseAudioDevice(g_dev, 0);
    return 1;
}

void audio_shutdown(void) {
    if (g_dev) SDL_CloseAudioDevice(g_dev);
    g_dev = 0; g_audio_ok = 0;
}

static void queue_tone(float freq, float dur, float vol, int kind) {
    if (!g_audio_ok) return;
    int n = (int)(22050 * dur);
    int16_t *buf = (int16_t *)calloc((size_t)n, sizeof(int16_t));
    for (int i = 0; i < n; i++) {
        float t = (float)i / 22050.0f;
        float env = (kind == 0) ? (1.0f - t / dur) : 1.0f;
        float s = sinf(2*3.14159f*freq*t);
        if (kind == 1) s = (sinf(2*3.14159f*freq*t) + 0.3f*sinf(2*3.14159f*freq*2*t));
        if (kind == 2) s = (sinf(2*3.14159f*freq*t) * (1.0f - t/dur)) ;
        buf[i] = (int16_t)(s * vol * 32767 * env);
    }
    SDL_QueueAudio(g_dev, buf, (Uint32)(n * sizeof(int16_t)));
    free(buf);
}

void audio_sfx(int id) {
    switch (id) {
    case 0: queue_tone(440, 0.08f, 0.25f, 0); break;   /* move  */
    case 1: queue_tone(220, 0.06f, 0.30f, 1); break;   /* shoot */
    case 2: queue_tone(90,  0.35f, 0.45f, 2); break;   /* boom  */
    case 3: queue_tone(660, 0.10f, 0.30f, 0); break;   /* build */
    case 4: queue_tone(880, 0.05f, 0.25f, 0); break;   /* select */
    case 5: queue_tone(140, 0.12f, 0.35f, 1); break;   /* error */
    default: break;
    }
}

void audio_music_start(void) { /* procedural drone; intentionally silent by default */ }
void audio_music_stop(void)  { /* no-op */ }

/* simple looping wasteland bassline (procedural, no asset files) */
static float g_music_t = 0;
static int   g_music_step = 0;
static const float g_bass[8] = { 110.0f, 0, 146.8f, 0, 130.8f, 0, 98.0f, 0 };
static const float g_mel[8]  = { 0, 329.6f, 0, 392.0f, 0, 293.7f, 0, 261.6f };

void audio_music_tick(float dt) {
    if (!g_audio_ok) return;
    g_music_t += dt;
    const float step_dur = 0.40f;
    if (g_music_t < step_dur) return;
    g_music_t -= step_dur;
    int s = g_music_step % 8;
    if (g_bass[s] > 0) queue_tone(g_bass[s], step_dur * 0.95f, 0.10f, 2);
    if (g_mel[s]  > 0) queue_tone(g_mel[s],  step_dur * 0.55f, 0.045f, 0);
    g_music_step++;
}