/*
 * mp3towav.c - decodifica um MP3 para WAV PCM 16 bits (mesma taxa e canais do arquivo), sempre com os mesmos bytes.
 * Usa o minimp3 (lieff/minimp3, CC0). Serve para o build-panspermia.sh, porque o SDL_mixer do pygbag nao toca MP3.
 * Copyright (C) 2026 FredyGames. Mesma licenca do wav2ogg: GNU GPL versao 2 ou posterior.
 *
 *   mp3towav entrada.mp3 saida.wav
 */
#define MINIMP3_IMPLEMENTATION
#include "minimp3_ex.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void put32(FILE *f, unsigned v) { fputc(v & 255, f); fputc(v >> 8 & 255, f); fputc(v >> 16 & 255, f); fputc(v >> 24 & 255, f); }
static void put16(FILE *f, unsigned v) { fputc(v & 255, f); fputc(v >> 8 & 255, f); }

int main(int argc, char **argv) {
  if (argc != 3) { fprintf(stderr, "uso: mp3towav entrada.mp3 saida.wav\n"); return 2; }
  mp3dec_t dec;
  mp3dec_file_info_t info;
  if (mp3dec_load(&dec, argv[1], &info, NULL, NULL) || !info.samples) { fprintf(stderr, "erro ao decodificar %s\n", argv[1]); return 1; }
  FILE *out = fopen(argv[2], "wb");
  if (!out) { perror(argv[2]); return 1; }
  unsigned bytes = info.samples * 2;
  fwrite("RIFF", 1, 4, out); put32(out, 36 + bytes); fwrite("WAVEfmt ", 1, 8, out);
  put32(out, 16); put16(out, 1); put16(out, info.channels); put32(out, info.hz);
  put32(out, info.hz * info.channels * 2); put16(out, info.channels * 2); put16(out, 16);
  fwrite("data", 1, 4, out); put32(out, bytes);
  for (size_t i = 0; i < info.samples; i++) put16(out, (unsigned short)info.buffer[i]);
  fclose(out);
  fprintf(stderr, "%s: %d Hz, %d canais, %.1f s\n", argv[1], info.hz, info.channels, (double)info.samples / info.channels / info.hz);
  free(info.buffer);
  return 0;
}