#include "zx_speaker.h"
#include <SDL2/SDL.h>
#include "z80.h"
#include <vector>

namespace speaker
{
    #define SAMPLING_FREQ 44100
    #define AUDIO_BUFFER_SIZE 2048
    SDL_AudioDeviceID sdlAudioDevice;
    uint8_t sound_buffer[AUDIO_BUFFER_SIZE];
    uint16_t sound_pos=0;
    uint16_t t_sound=0;
    std::vector<uint8_t(*)()> sources;

    float cycles_per_sample;

    void init()
    {
        SDL_AudioSpec audioSpec{SAMPLING_FREQ, AUDIO_U8, 1, 0, AUDIO_BUFFER_SIZE>>2, 0, 0, NULL, NULL};
        sdlAudioDevice = SDL_OpenAudioDevice(NULL, 0, &audioSpec, NULL, 0);
        cycles_per_sample = z80::getClock() / SAMPLING_FREQ;
        enable();
    }

    void enable()
    {
        SDL_PauseAudioDevice(sdlAudioDevice, 0);
    }

    void disable()
    {
        SDL_PauseAudioDevice(sdlAudioDevice, 1);
    }

    void register_source(uint8_t(*callback)())
    {
        sources.push_back(callback);
    }

    void update(const uint8_t dt)
    {
        t_sound += dt;
        if (t_sound>=cycles_per_sample) {
            t_sound-=cycles_per_sample;

            uint32_t sample = 0;
            for (auto callback : sources) sample += callback();
            sample /= sources.size();
            
            sound_buffer[(sound_pos++)&(AUDIO_BUFFER_SIZE-1)] = sample;
        }
        if (sound_pos>=1000) {
            SDL_QueueAudio(sdlAudioDevice, sound_buffer, sound_pos);
            sound_pos = 0;
            while (SDL_GetQueuedAudioSize(sdlAudioDevice) > 4096 ) {}
        }
    }

}