#define ALSA_PCM_NEW_HW_PARAMS_API
#include <alsa/asoundlib.h>

#include "audio.h"
#include "typedef.h"

#define TEMP_BUF_SZ (handle->frames * CHANNELS * 2)
#define HANDLE (*(snd_pcm_t**)(handle->h))

#define MIN(a,b) (((a)<(b))?(a):(b))

int audio_create(audio_handle *handle, audio_handle_types t)
{
    handle->h = malloc(sizeof(snd_pcm_t *));
    snd_pcm_stream_t type = (t == RECORD) ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK;
    int rc = snd_pcm_open(handle->h, "default", type, 0);
    if (rc < 0) {
        err("unable to open pcm device: %s\n", snd_strerror(rc));
        return 1;
    }

    int dir;
    snd_pcm_hw_params_t *params;

    snd_pcm_hw_params_alloca(&params); // allocate params
    snd_pcm_hw_params_any(HANDLE, params); // set params
    snd_pcm_hw_params_set_access(HANDLE, params, SND_PCM_ACCESS_RW_INTERLEAVED); // interleaved mode
    snd_pcm_hw_params_set_format(HANDLE, params, SND_PCM_FORMAT_S16_LE);

    snd_pcm_hw_params_set_channels(HANDLE, params, CHANNELS);

    unsigned int samp_rate = SAMPLING_RATE;
    snd_pcm_hw_params_set_rate_near(HANDLE, params, &samp_rate, &dir);

    snd_pcm_uframes_t frames = FRAMES;
    snd_pcm_hw_params_set_period_size_near(HANDLE, params, &frames, &dir);

    rc = snd_pcm_hw_params(HANDLE, params); // write params to handle
    if (rc < 0) {
        err("unable to set hw parameters: %s\n", snd_strerror(rc));
        return 1;
    }

    snd_pcm_hw_params_get_period_size(params, &frames, &dir);
    handle->frames = frames;

    return 0;
}

int audio_play(audio_handle *handle, char *buf)
{
    char t[TEMP_BUF_SZ];
    for(int i = 0; ;)
    {
        if(i >= REC_CAP) break;;

        memset(t, 0, TEMP_BUF_SZ);
        memcpy(t, &(buf[i]), MIN(TEMP_BUF_SZ, REC_CAP - i));

        int rc = snd_pcm_writei(HANDLE, t, FRAMES);
        if (rc == -EPIPE) {
            err("underrun occurred\n");
            snd_pcm_prepare(HANDLE);
        } else if (rc < 0) {
            err("error from writei: %s\n", snd_strerror(rc));
        }  else if (rc != FRAMES) {
            err("short write, write %d frames\n", rc);
        }

        i += TEMP_BUF_SZ;
    }
    return 0;
}

int audio_record(audio_handle *handle, char *buf)
{
    char t[TEMP_BUF_SZ];
    for(int i = 0; ;)
    {
        if(i >= REC_CAP) break;
        memset(t, 0, TEMP_BUF_SZ);

        int rc = snd_pcm_readi(HANDLE, t, FRAMES);
        if (rc == -EPIPE) {
            err("overrun occurred\n");
            snd_pcm_prepare(HANDLE);
        } else if (rc < 0) {
            err("error from read: %s\n", snd_strerror(rc));
        } else if (rc != FRAMES) {
            err("short read, read %d frames\n", rc);
        }

        memcpy(&(buf[i]), t, MIN(TEMP_BUF_SZ, REC_CAP - i));
        i += TEMP_BUF_SZ;
    }

    return 0;
}

void audio_destroy(audio_handle *handle)
{
    snd_pcm_drain(HANDLE);
    snd_pcm_close(HANDLE);
    free(handle->h);
}