#include <AL/al.h>
#include <AL/alc.h>
#include <vorbis/vorbisfile.h>
#include <SDL.h>

#include "lephisto.h"
#include "log.h"
#include "pack.h"
#include "music.h"

#define MUSIC_STOPPED   (1<<1)
#define MUSIC_PLAYING   (1<<2)
#define MUSIC_KILL    (1<<9)
#define music_is(f)    (music_state  & f)
#define music_set(f)   (music_state |= f)
#define music_rm(f)    (music_state ^= f)

#define MUSIC_PREFIX   "../snd/music/"
#define MUSIC_SUFFIX   ".ogg"

#define BUFFER_SIZE    (4096 * 8)

// Gobal sound mutex.
extern SDL_mutex* sound_lock;

// Saves the music to ram in this structure.
typedef struct alMusic_ {
  char name[32]; // Name.
  Packfile file;
  OggVorbis_File stream;
  vorbis_info* info;
  ALenum format;
} alMusic;

// Song currently playing.
static SDL_mutex* music_vorbis_lock;
static alMusic music_vorbis;
static ALuint music_buffer[2]; // Front and back buffer.
static ALuint music_source = 0;

// What is available?
static char** music_selection = NULL;
static int nmusic_selection = 0;

// Volume
static ALfloat mvolume = 1.;

// Vorbis suff.
static size_t ovpack_read(void* ptr, size_t size,
                          size_t nmemb, void* datasource) {
  return (ssize_t) pack_read(datasource, ptr, size*nmemb);
}

static int ovpack_retneg(void) { return -1; } // Must return -1.
static int ovpack_retzero(void) { return 0; } // Must return 0.
ov_callbacks ovcall = {
  .read_func  = ovpack_read,
  .seek_func  = (int(*)(void*, ogg_int64_t, int)) ovpack_retneg,
  .close_func = (int(*)(void*))ovpack_retzero,
  .tell_func = (long(*)(void*))ovpack_retneg
};

static int stream_loadBuffer(ALuint buffer);
static int music_find(void);
static int music_loadOGG(const char* filename);
static void music_free(void);

// The thread.
static unsigned int music_state = 0;
int music_thread(void* unused) {
  (void)unused;

  int active; // Active buffer.
  ALint stat;

  // Main loop.
  while(!music_is(MUSIC_KILL)) {
    if(music_is(MUSIC_PLAYING)) {
      if(music_vorbis.file.end == 0)
        music_rm(MUSIC_PLAYING);
      else {
        music_rm(MUSIC_STOPPED);

        SDL_mutexP(music_vorbis_lock); // Lock the mutex.
        SDL_mutexP(sound_lock);

        // Start playing current song.
        active = 0; // Load first buffer.
        if(stream_loadBuffer(music_buffer[active])) music_rm(MUSIC_PLAYING);
        alSourceQueueBuffers(music_source, 1, &music_buffer[active]);

        // Start playing with buffer laoaded.
        alSourcePlay(music_source);

        active = 1; // Load the second buffer.
        if(stream_loadBuffer(music_buffer[active])) music_rm(MUSIC_PLAYING);
        alSourceQueueBuffers(music_source, 1, &music_buffer[active]);

        SDL_mutexV(sound_lock);

        active = 0;
      }
      while(music_is(MUSIC_PLAYING)) {
        SDL_mutexP(sound_lock);

        alGetSourcei(music_source, AL_BUFFERS_PROCESSED, &stat);
        if(stat > 0) {
          // Refill active buffer.
          alSourceUnqueueBuffers(music_source, 1, &music_buffer[active]);
          if(stream_loadBuffer(music_buffer[active])) music_rm(MUSIC_PLAYING);
          alSourceQueueBuffers(music_source, 1, &music_buffer[active]);

          active = 1 - active;
        }
        SDL_mutexV(sound_lock);

        SDL_Delay(0);
      }
      SDL_mutexP(sound_lock);

      alSourceStop(music_source);
      alSourceUnqueueBuffers(music_source, 2, music_buffer);

      SDL_mutexV(sound_lock);
      SDL_mutexV(music_vorbis_lock);
    }
    music_set(MUSIC_STOPPED);
    SDL_Delay(0); // We must not kill resources.
  }
  return 0;
}

static int stream_loadBuffer(ALuint buffer) {
  int size, section, result;
  char data[BUFFER_SIZE]; // Buffer to hold the data.

  size = 0;
  while(size < BUFFER_SIZE) {
    // Fill up the entire data buffer.
    result = ov_read(
          &music_vorbis.stream,  // Stream.
          data + size,      // Data.
          BUFFER_SIZE - size,   // Amount to read.
          0,           // Big endian?.
          2,           // 16 bit.
          1,           // Signed.
          &section);       // Current bitstream.

    if(result == 0) return 1;
    else if(result == OV_HOLE) {
      WARN("OGG: Vorbis hole detected in music!");
      return 0;
    }
    else if(result == OV_EBADLINK) {
      WARN("OGG: Invalid stream section or corrupt link in music!");
      return -1;
    }

    size += result;
    if(size == BUFFER_SIZE) break; // Buffer is full.
  }
  // Load the buffer.
  alBufferData(buffer, music_vorbis.format, data, BUFFER_SIZE,
               music_vorbis.info->rate);

  return 0;
}

// Init/Exit.
int music_init(void) {
  music_vorbis_lock = SDL_CreateMutex();
  music_find();
  music_vorbis.file.end = 0; // Indication that it's not loaded..

  SDL_mutexP(sound_lock);

  alGenBuffers(2, music_buffer);
  alGenSources(1, &music_source);
  alSourcef(music_source, AL_GAIN, mvolume);
  alSourcef(music_source, AL_ROLLOFF_FACTOR, 0.);
  alSourcei(music_source, AL_SOURCE_RELATIVE, AL_TRUE);

  SDL_mutexV(sound_lock);

  return 0;
}

void music_exit(void) {
  int i;

  // Free the music.
  alDeleteBuffers(2, music_buffer);
  alDeleteSources(1, &music_source);
  music_free();

  // Free selection
  for(i = 0; i < nmusic_selection; i++)
    free(music_selection[i]);
  free(music_selection);

  SDL_DestroyMutex(music_vorbis_lock);
}

// Internal music loading ruitines.
static int music_loadOGG(const char* filename) {
  // Free currently loaded ogg.
  music_free();

  SDL_mutexP(music_vorbis_lock);

  // Load the new ogg.
  pack_open(&music_vorbis.file, DATA, filename);
  ov_open_callbacks(&music_vorbis.file, &music_vorbis.stream, NULL, 0, ovcall);
  music_vorbis.info = ov_info(&music_vorbis.stream, -1);

  if(music_vorbis.info->channels == 1) music_vorbis.format = AL_FORMAT_MONO16;
  else music_vorbis.format = AL_FORMAT_STEREO16;

  SDL_mutexV(music_vorbis_lock);
  return 0;
}

static int music_find(void) {
  char** files;
  uint32_t nfiles, i;
  char tmp[64];
  int len;

  // Get the file list.
  files = pack_listfiles(data, &nfiles);

  // Load the profiles.
  for(i = 0; i < nfiles; i++)
    if((strncmp(files[i], MUSIC_PREFIX, strlen(MUSIC_PREFIX))==0) &&
       (strncmp(files[i] + strlen(files[i]) - strlen(MUSIC_SUFFIX),
                MUSIC_SUFFIX, strlen(MUSIC_SUFFIX))==0)) {

      // Grow the selection size.
      music_selection = realloc(music_selection,++nmusic_selection*sizeof(char*));

      // Remove the prefix and suffix.
      len = strlen(files[i]) - strlen(MUSIC_SUFFIX MUSIC_PREFIX);
      strncpy(tmp, files[i]  + strlen(MUSIC_PREFIX), len);
      tmp[len] = '\0';

      music_selection[nmusic_selection-1] = strdup(tmp);
    }
  // Free the char* allocated by pack.
  for(i = 0; i < nfiles; i++)
    free(files[i]);
  free(files);

  DEBUG("Loaded %d song%c", nmusic_selection, (nmusic_selection==1)?' ':'s');

  return 0;
}

static void music_free(void) {
  SDL_mutexP(music_vorbis_lock);

  if(music_vorbis.file.end != 0) {
    ov_clear(&music_vorbis.stream);
    pack_close(&music_vorbis.file);
    music_vorbis.file.end = 0; // Somewhat ended.
  }

  SDL_mutexV(music_vorbis_lock);
}

void music_volume(const double vol) {
  if(sound_lock == NULL) return;

  // Sanity check!
  ALfloat fvol = ABS(vol);
  if(fvol > 1.) fvol = 1.;

  mvolume = fvol;

  // Only needed if playing!
  if(music_set(MUSIC_PLAYING)) {
    SDL_mutexP(sound_lock);
    alSourcef(music_source, AL_GAIN, fvol);
    SDL_mutexV(sound_lock);
  }
}

// Music control functions.
void music_load(const char* name) {
  if(sound_lock == NULL) return;

  int i;
  char tmp[64];

  music_stop();
  while(!music_is(MUSIC_STOPPED)) SDL_Delay(0);

  for(i = 0; i < nmusic_selection; i++)
    if(strcmp(music_selection[i], name)==0) {
      snprintf(tmp, 64, MUSIC_PREFIX"%s"MUSIC_SUFFIX, name);
      music_loadOGG(tmp);
      return;
    }
  WARN("Requested load song '%s' but it can't be found in the music stack",name);
}

void music_play(void) {
  if(!music_is(MUSIC_PLAYING)) music_set(MUSIC_PLAYING);
}

void music_stop(void) {
  if(music_is(MUSIC_PLAYING)) music_rm(MUSIC_PLAYING);
}

void music_kill(void) {
  if(!music_is(MUSIC_KILL)) music_set(MUSIC_KILL);
}