/*
 * modrender.c - renderiza um modulo de tracker (.s3m, .xm, .mod, .it) em WAV PCM 16 bits estereo, 44100 Hz, ate o
 * fim da musica (ou ate o primeiro ponto de repeticao), sempre com os mesmos bytes. Usa a libxmp.
 * Escrito para o fredygames.com (musicas dos jogos de pygame: o SDL_mixer do pygbag nao toca modulos).
 * Copyright (C) 2026 FredyGames. Licenca: MIT.
 *
 *   modrender entrada.xm saida.wav [segundos-maximos]
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <xmp.h>

static void put32(unsigned char *p, unsigned v) { p[0] = v; p[1] = v >> 8; p[2] = v >> 16; p[3] = v >> 24; }

int main(int argc, char **argv) {
  if (argc < 3) { fprintf(stderr, "uso: modrender entrada saida.wav [segundos]\n"); return 2; }
  double max_seconds = argc > 3 ? atof(argv[3]) : 600;
  xmp_context ctx = xmp_create_context();
  if (xmp_load_module(ctx, argv[1]) < 0) { fprintf(stderr, "nao consegui carregar %s\n", argv[1]); return 1; }
  const int rate = 44100;
  if (xmp_start_player(ctx, rate, 0) < 0) { fprintf(stderr, "erro no player\n"); return 1; }
  FILE *out = fopen(argv[2], "wb");
  if (!out) { perror(argv[2]); return 1; }
  unsigned char hdr[44] = {0};
  fwrite(hdr, 1, 44, out);
  unsigned long bytes = 0, limit = (unsigned long)(max_seconds * rate) * 4;
  struct xmp_frame_info fi;
  for (;;) {
    if (xmp_play_frame(ctx) != 0) break;
    xmp_get_frame_info(ctx, &fi);
    if (fi.loop_count > 0) break;
    fwrite(fi.buffer, 1, fi.buffer_size, out);
    bytes += fi.buffer_size;
    if (bytes >= limit) break;
  }
  memcpy(hdr, "RIFF", 4); put32(hdr + 4, 36 + bytes); memcpy(hdr + 8, "WAVEfmt ", 8);
  put32(hdr + 16, 16); hdr[20] = 1; hdr[22] = 2; put32(hdr + 24, rate); put32(hdr + 28, rate * 4); hdr[32] = 4; hdr[34] = 16;
  memcpy(hdr + 36, "data", 4); put32(hdr + 40, bytes);
  fseek(out, 0, SEEK_SET); fwrite(hdr, 1, 44, out); fclose(out);
  xmp_end_player(ctx); xmp_release_module(ctx); xmp_free_context(ctx);
  fprintf(stderr, "%s: %.1f s\n", argv[2], bytes / 4.0 / rate);
  return 0;
}