/*
 * tbzmusic.c: the game's music over libmodplug, through Mix_HookMusic (see tbzmusic.h).
 * Copyright (C) 2026 FredyGames. GNU GPL version 3 or later, like TecnoballZ.
 */
#define TBZ_MUSIC_IMPLEMENTATION
#include "tbzmusic.h"
#include <libmodplug/modplug.h>
#include <stdlib.h>
#include <string.h>

typedef struct
{
  ModPlugFile *file;
  MODULE module;
} tbz_music;

static tbz_music *playing = NULL;
static int paused = 0;
static int volume = MIX_MAX_VOLUME;

/* number of orders of a ProTracker module (31 samples: song length at offset 950) */
static int
module_orders (const Uint8 * data, size_t size)
{
  if (size > 950 && data[950] > 0 && data[950] <= 128)
    return data[950];
  return 1;
}

Mix_Music *
tbz_LoadMUS (const char *path)
{
  SDL_RWops *rw = SDL_RWFromFile (path, "rb");
  Sint64 size;
  Uint8 *data;
  tbz_music *music;
  ModPlug_Settings settings;
  int frequency = 44100, channels = 2;
  Uint16 format;

  if (rw == NULL)
    return NULL;
  size = SDL_RWsize (rw);
  data = (Uint8 *) malloc (size > 0 ? (size_t) size : 1);
  if (data == NULL || size <= 0 || SDL_RWread (rw, data, 1, (size_t) size) != (size_t) size)
    {
      SDL_RWclose (rw);
      free (data);
      SDL_SetError ("cannot read %s", path);
      return NULL;
    }
  SDL_RWclose (rw);

  /* the module plays at the mixer's rate, in 16-bit samples */
  Mix_QuerySpec (&frequency, &format, &channels);
  ModPlug_GetSettings (&settings);
  settings.mFrequency = frequency;
  settings.mChannels = channels >= 2 ? 2 : 1;
  settings.mBits = 16;
  settings.mResamplingMode = MODPLUG_RESAMPLE_LINEAR;
  settings.mLoopCount = -1;
  ModPlug_SetSettings (&settings);

  music = (tbz_music *) calloc (1, sizeof (tbz_music));
  music->file = ModPlug_Load (data, (int) size);
  music->module.numpos = module_orders (data, (size_t) size);
  free (data);
  if (music->file == NULL)
    {
      free (music);
      SDL_SetError ("cannot load the module %s", path);
      return NULL;
    }
  return (Mix_Music *) music;
}

static void SDLCALL
mix_music (void *udata, Uint8 * stream, int len)
{
  tbz_music *music = (tbz_music *) udata;
  int done = 0;
  memset (stream, 0, len);
  if (music == NULL || music->file == NULL || paused)
    return;
  while (done < len)
    {
      int n = ModPlug_Read (music->file, stream + done, len - done);
      if (n <= 0)
        {
          /* end of the song: start again, as MikMod does with loops = -1 */
          ModPlug_SeekOrder (music->file, 0);
          break;
        }
      done += n;
    }
  if (volume < MIX_MAX_VOLUME)
    {
      Sint16 *s = (Sint16 *) stream;
      int i;
      for (i = 0; i < len / 2; i++)
        s[i] = (Sint16) ((s[i] * volume) / MIX_MAX_VOLUME);
    }
  music->module.sngpos = ModPlug_GetCurrentOrder (music->file);
  music->module.patpos = ModPlug_GetCurrentRow (music->file);
}

int
tbz_PlayMusic (Mix_Music * m, int loops)
{
  tbz_music *music = (tbz_music *) m;
  (void) loops;
  if (music == NULL)
    return -1;
  Mix_HookMusic (NULL, NULL);
  ModPlug_SeekOrder (music->file, 0);
  music->module.sngpos = 0;
  music->module.patpos = 0;
  playing = music;
  paused = 0;
  Mix_HookMusic (mix_music, music);
  return 0;
}

int
tbz_HaltMusic (void)
{
  Mix_HookMusic (NULL, NULL);
  playing = NULL;
  return 0;
}

void
tbz_FreeMusic (Mix_Music * m)
{
  tbz_music *music = (tbz_music *) m;
  if (music == NULL)
    return;
  if (music == playing)
    tbz_HaltMusic ();
  ModPlug_Unload (music->file);
  free (music);
}

int
tbz_SetMusicPosition (double position)
{
  if (playing == NULL)
    return -1;
  SDL_LockAudio ();
  ModPlug_SeekOrder (playing->file, (int) position);
  playing->module.sngpos = (int) position;
  playing->module.patpos = 0;
  SDL_UnlockAudio ();
  return 0;
}

int
tbz_VolumeMusic (int v)
{
  int previous = volume;
  if (v >= 0)
    volume = v > MIX_MAX_VOLUME ? MIX_MAX_VOLUME : v;
  return previous;
}

MODULE *
tbz_music_module (Mix_Music * m)
{
  return m == NULL ? NULL : &((tbz_music *) m)->module;
}

int
Player_Paused (void)
{
  return paused;
}

void
Player_TogglePause (void)
{
  paused = !paused;
}

void
Player_Stop (void)
{
  /* the game calls it right after starting a level's music; with SDL_mixer's MikMod backend the
   * music keeps playing, so there is nothing to do here */
}