#include "jail_audio.h"
#include "stb_vorbis.c"
#include <SDL2/SDL.h>

#define JA_MAX_SIMULTANEOUS_SOUNDS 5

struct JA_Sound_t {
    Uint32 length {0};
    Uint8 *buffer {NULL};
};

struct JA_Sound_Playing_t {
    Uint32 length {0};
    int pos {0};
    Uint8 *buffer {NULL};
    JA_Sound_Playing_t* prev {NULL};
    JA_Sound_Playing_t* next {NULL};
};

enum JA_Music_state { JA_MUSIC_INVALID, JA_MUSIC_PLAYING, JA_MUSIC_PAUSED, JA_MUSIC_STOPPED };

struct JA_Music_t {
    int samples {0};
    int pos {0};
    short *output {NULL};
    JA_Music_state state {JA_MUSIC_INVALID};
    bool loop {false};
};

JA_Music current_music{NULL};
JA_Sound_Playing_t sounds[JA_MAX_SIMULTANEOUS_SOUNDS];
JA_Sound_Playing_t *first_sound {NULL};
JA_Sound_Playing_t *last_sound {NULL};
JA_Sound_Playing_t *free_sounds_list {NULL};

int JA_freq {48000};
SDL_AudioFormat JA_format {AUDIO_S16};
Uint8 JA_channels {2};

void audioCallback(void * userdata, uint8_t * stream, int len) {
    SDL_memset(stream, 0, len);
    if (current_music != NULL && current_music->state == JA_MUSIC_PLAYING) {
        const int size = SDL_min(len, current_music->samples*2-current_music->pos);
        SDL_memcpy(stream, current_music->output+current_music->pos, size);
        current_music->pos += size/2;
        if (size < len) {
            if (current_music->loop) {
                SDL_memcpy(stream+size, current_music->output, len-size);
                current_music->pos = (len-size)/2;
            } else {
                current_music->pos = 0;
                current_music->state = JA_MUSIC_STOPPED;
            }
        }
    }
    // Mixar els sounds mi amol
    JA_Sound_Playing_t *sound = first_sound;
    while (sound != NULL) {
        const int size = SDL_min(len, sound->length-sound->pos);
        SDL_MixAudioFormat(stream, sound->buffer+sound->pos, AUDIO_S16, size, 64);
        sound->pos += size;
        if (size < len) {
            if (sound == last_sound) last_sound = sound->prev;
            if (sound == first_sound) first_sound = sound->next;
            if (sound->prev != NULL) sound->prev->next = sound->next;
            if (sound->next != NULL) sound->next->prev = sound->prev;
            if (free_sounds_list == NULL) {
                free_sounds_list = sound;
                sound = sound->next;
                free_sounds_list->prev = free_sounds_list->next = NULL;
            } else {
                free_sounds_list->prev = sound;
                sound = sound->next;
                free_sounds_list->prev->next = free_sounds_list;
                free_sounds_list = free_sounds_list->prev;
                free_sounds_list->prev = NULL;
            }
        } else {
            sound = sound->next;
        }
    }
}

void JA_Init(const int freq, const SDL_AudioFormat format, const int channels) {
    JA_freq = freq;
    JA_format = format;
    JA_channels = channels;
    SDL_AudioSpec audioSpec{JA_freq, JA_format, JA_channels, 0, 1024, 0, 0, audioCallback, NULL};
    SDL_AudioDeviceID sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
    free_sounds_list = &sounds[0];
    for (int i = 0; i < JA_MAX_SIMULTANEOUS_SOUNDS-2;i++) {
        sounds[i].next = &sounds[i+1]; sounds[i+1].prev = &sounds[i];
    }
    SDL_PauseAudioDevice(sdlAudioDevice, 0);
}

JA_Music JA_LoadMusic(const char* filename) {
    int chan, samplerate;
    JA_Music music = (JA_Music)SDL_malloc(sizeof(JA_Music_t));
    music->samples = stb_vorbis_decode_filename(filename, &chan, &samplerate, &music->output);

    SDL_AudioCVT cvt;
    SDL_BuildAudioCVT(&cvt, AUDIO_S16, chan, samplerate, JA_format, JA_channels, JA_freq);
    cvt.len = music->samples * chan * 2;
    cvt.buf = (Uint8 *) SDL_malloc(cvt.len * cvt.len_mult);
    SDL_memcpy(cvt.buf, music->output, cvt.len);
    SDL_ConvertAudio(&cvt);
    free(music->output);
    music->output = (short*)cvt.buf;

    music->pos = 0;
    music->state = JA_MUSIC_STOPPED;

    return music;
}

void JA_PlayMusic(JA_Music music, const bool loop) {
    int chan, samplerate;
    if (current_music != NULL) {
        current_music->pos = 0;
        current_music->state = JA_MUSIC_STOPPED;
    }
    current_music = music;
    current_music->pos = 0;
    current_music->state = JA_MUSIC_PLAYING;
    current_music->loop = loop;
}

void JA_PauseMusic() {
    if (current_music->state == JA_MUSIC_INVALID) return;
    current_music->state = JA_MUSIC_PAUSED;
}

void JA_ResumeMusic() {
    if (current_music->state == JA_MUSIC_INVALID) return;
    current_music->state = JA_MUSIC_PLAYING;
}

void JA_StopMusic() {
    if (current_music->state == JA_MUSIC_INVALID) return;
    current_music->pos = 0;
    current_music->state = JA_MUSIC_STOPPED;
}

bool JA_IsMusicPlaying() {
    return current_music->state == JA_MUSIC_PLAYING;
}

void JA_DeleteMusic(JA_Music music) {
    if (current_music == music) current_music = NULL;
    free(music->output);
    free(music);
}

JA_Sound JA_LoadSound(const char* filename) {
    JA_Sound sound = new JA_Sound_t();
    SDL_AudioSpec wavSpec;
    SDL_LoadWAV(filename, &wavSpec, &sound->buffer, &sound->length);

    SDL_AudioCVT cvt;
    SDL_BuildAudioCVT(&cvt, wavSpec.format, wavSpec.channels, wavSpec.freq, JA_format, JA_channels, JA_freq);
    cvt.len = sound->length;
    cvt.buf = (Uint8 *) SDL_malloc(cvt.len * cvt.len_mult);
    SDL_memcpy(cvt.buf, sound->buffer, sound->length);
    SDL_ConvertAudio(&cvt);
    free(sound->buffer);
    sound->buffer = cvt.buf;
    sound->length = cvt.len_cvt;

    return sound;
}

void JA_PlaySound(JA_Sound sound) {
    if (free_sounds_list == NULL) {
        first_sound->prev = last_sound;
        last_sound->next = first_sound;
        last_sound = first_sound;
        first_sound = last_sound->next;
        first_sound->prev = last_sound->next = NULL;
    } else {
        if (last_sound != NULL)
            last_sound->next = free_sounds_list;
        last_sound = free_sounds_list;
        if (free_sounds_list->next != NULL) free_sounds_list->next->prev = NULL;
        free_sounds_list = last_sound->next;
        last_sound->next = NULL;
        if (first_sound == NULL) first_sound = last_sound;
    }
    last_sound->buffer = sound->buffer;
    last_sound->length = sound->length;
    last_sound->pos = 0;
}

void JA_DeleteSound(JA_Sound sound) {
    SDL_FreeWAV(sound->buffer);
    delete sound;
}