/*
 * Copyright (C) 2006 Michael Niedermayer
 * Copyright (C) 2004 Alex Beregszaszi
 * based upon af_extrastereo.c by Pierre Lombard
 *
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <inttypes.h>
#include <math.h>
#include <limits.h>

#include "af.h"

// Data for specific instances of this filter
typedef struct af_sinesuppress_s
{
    double freq;
    double decay;
    double real;
    double imag;
    double ref;
    double pos;
}af_sinesuppress_t;

// Initialization and runtime control
static int control(struct af_instance* af, int cmd, void* arg)
{
  switch(cmd){
  case AF_CONTROL_REINIT:{
    // Sanity check
    if(!arg) return AF_ERROR;

    mp_audio_copy_config(af->data, (struct mp_audio*)arg);
    mp_audio_set_num_channels(af->data, 1);
    mp_audio_set_format(af->data, AF_FORMAT_S16);

    return af_test_output(af,(struct mp_audio*)arg);
  }
  }
  return AF_UNKNOWN;
}

static int play_s16(struct af_instance *af, struct mp_audio *data)
{
  if (!data)
    return 0;
  if (af_make_writeable(af, data) < 0) {
    talloc_free(data);
    return -1;
  }

  af_sinesuppress_t *s = af->priv;
  register int i = 0;
  int16_t *a = (int16_t*)data->planes[0];       // Audio data
  int len = data->samples*data->nch;            // Number of samples

  for (i = 0; i < len; i++)
  {
    double co= cos(s->pos);
    double si= sin(s->pos);

    s->real += co * a[i];
    s->imag += si * a[i];
    s->ref  += co * co;

    a[i] -= (s->real * co + s->imag * si) / s->ref;

    s->real -= s->real * s->decay;
    s->imag -= s->imag * s->decay;
    s->ref  -= s->ref  * s->decay;

    s->pos += 2 * M_PI * s->freq / data->rate;
  }

   MP_VERBOSE(af, "f:%8.2f: amp:%8.2f\n", s->freq, sqrt(s->real*s->real + s->imag*s->imag) / s->ref);

  af_add_output_frame(af, data);
  return 0;
}

// Allocate memory and set function pointers
static int af_open(struct af_instance* af){
  af->control=control;
  af->filter_frame = play_s16;
  return AF_OK;
}

#define OPT_BASE_STRUCT af_sinesuppress_t
const struct af_info af_info_sinesuppress = {
    .info = "Sine Suppress",
    .name = "sinesuppress",
    .open = af_open,
    .priv_size = sizeof(af_sinesuppress_t),
    .options = (const struct m_option[]) {
        OPT_DOUBLE("freq", freq, 0, OPTDEF_DOUBLE(50.0)),
        OPT_DOUBLE("decay", decay, 0, OPTDEF_DOUBLE(0.0001)),
        {0}
    },
};