/*
  * Copyright (c) 2015 Kyle Swanson <k@ylo.ph>.
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "internal.h"
 #include "audio.h"
 #include "generate_wave_table.h"
 
 typedef struct VibratoContext {
     const AVClass *class;
     double freq;
     double depth;
     int channels;
 
     double **buf;
     int buf_index;
     int buf_size;
 
     double *wave_table;
     int wave_table_index;
     int wave_table_size;
 } VibratoContext;
 
 #define OFFSET(x) offsetof(VibratoContext, x)
 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 
 static const AVOption vibrato_options[] = {
     { "f", "set frequency in hertz",    OFFSET(freq),    AV_OPT_TYPE_DOUBLE,   {.dbl = 5.0},   0.1,   20000.0, FLAGS },
     { "d", "set depth as percentage",   OFFSET(depth),   AV_OPT_TYPE_DOUBLE,   {.dbl = 0.5},   0.00,  1.0,     FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(vibrato);
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     VibratoContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
     AVFrame *out;
     int n, c;
     const double *src;
     double *dst;
 
     if (av_frame_is_writable(in)) {
         out = in;
     } else {
         out = ff_get_audio_buffer(inlink, in->nb_samples);
         if (!out) {
             av_frame_free(&in);
             return AVERROR(ENOMEM);
         }
         av_frame_copy_props(out, in);
     }
 
 
     for (n = 0; n < in->nb_samples; n++) {
         double integer, decimal;
         decimal = modf(s->depth * s->wave_table[s->wave_table_index], &integer);
 
         s->wave_table_index++;
         if (s->wave_table_index >= s->wave_table_size)
             s->wave_table_index -= s->wave_table_size;
 
         for (c = 0; c < inlink->channels; c++) {
             int samp1_index, samp2_index;
             double *buf;
             double this_samp;
 
             src = (const double *)in->extended_data[c];
             dst = (double *)out->extended_data[c];
             buf = s->buf[c];
 
             samp1_index = s->buf_index + integer;
             if (samp1_index >= s->buf_size)
                 samp1_index -= s->buf_size;
             samp2_index = samp1_index + 1;
             if (samp2_index >= s->buf_size)
                 samp2_index -= s->buf_size;
 
             this_samp = src[n];
             dst[n] = buf[samp1_index] + (decimal * (buf[samp2_index] - buf[samp1_index]));
             buf[s->buf_index] = this_samp;
         }
         s->buf_index++;
         if (s->buf_index >= s->buf_size)
             s->buf_index -= s->buf_size;
     }
 
     if (in != out)
         av_frame_free(&in);
 
     return ff_filter_frame(outlink, out);
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats;
     AVFilterChannelLayouts *layouts;
     static const enum AVSampleFormat sample_fmts[] = {
         AV_SAMPLE_FMT_DBLP,
         AV_SAMPLE_FMT_NONE
     };
     int ret;
 
     layouts = ff_all_channel_counts();
     if (!layouts)
         return AVERROR(ENOMEM);
     ret = ff_set_common_channel_layouts(ctx, layouts);
     if (ret < 0)
         return ret;
 
     formats = ff_make_format_list(sample_fmts);
     if (!formats)
         return AVERROR(ENOMEM);
     ret = ff_set_common_formats(ctx, formats);
     if (ret < 0)
         return ret;
 
     formats = ff_all_samplerates();
     if (!formats)
         return AVERROR(ENOMEM);
     return ff_set_common_samplerates(ctx, formats);
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     VibratoContext *s = ctx->priv;
     int c;
 
     av_freep(&s->wave_table);
     for (c = 0; c < s->channels; c++)
         av_freep(&s->buf[c]);
     av_freep(&s->buf);
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     int c;
     AVFilterContext *ctx = inlink->dst;
     VibratoContext *s = ctx->priv;
     s->channels = inlink->channels;
 
     s->buf = av_calloc(inlink->channels, sizeof(*s->buf));
     if (!s->buf)
         return AVERROR(ENOMEM);
     s->buf_size = inlink->sample_rate * 0.005;
     for (c = 0; c < s->channels; c++) {
         s->buf[c] = av_malloc_array(s->buf_size, sizeof(*s->buf[c]));
         if (!s->buf[c])
             return AVERROR(ENOMEM);
     }
     s->buf_index = 0;
 
     s->wave_table_size = inlink->sample_rate / s->freq;
     s->wave_table = av_malloc_array(s->wave_table_size, sizeof(*s->wave_table));
     if (!s->wave_table)
         return AVERROR(ENOMEM);
     ff_generate_wave_table(WAVE_SIN, AV_SAMPLE_FMT_DBL, s->wave_table, s->wave_table_size, 0.0, s->buf_size - 1, 3.0 * M_PI_2);
     s->wave_table_index = 0;
 
     return 0;
 }
 
 static const AVFilterPad avfilter_af_vibrato_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_AUDIO,
         .config_props = config_input,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad avfilter_af_vibrato_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_AUDIO,
     },
     { NULL }
 };
 
 AVFilter ff_af_vibrato = {
     .name          = "vibrato",
     .description   = NULL_IF_CONFIG_SMALL("Apply vibrato effect."),
     .priv_size     = sizeof(VibratoContext),
     .priv_class    = &vibrato_class,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = avfilter_af_vibrato_inputs,
     .outputs       = avfilter_af_vibrato_outputs,
 };