/*
  * Copyright (c) 2011 Stefano Sabatini
  *
  * 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
  */
 
 /**
  * @file
  * eval audio source
  */
 
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"

 #include "libavutil/channel_layout.h"

 #include "libavutil/eval.h"
 #include "libavutil/opt.h"

 #include "libavutil/parseutils.h"

 #include "avfilter.h"

 #include "audio.h"

 #include "internal.h"
 

 static const char * const var_names[] = {

     "n",            ///< number of frame
     "t",            ///< timestamp expressed in seconds
     "s",            ///< sample rate
     NULL
 };
 
 enum var_name {
     VAR_N,
     VAR_T,
     VAR_S,
     VAR_VARS_NB
 };
 
 typedef struct {
     const AVClass *class;
     char *sample_rate_str;
     int sample_rate;
     int64_t chlayout;

     char *chlayout_str;

     int nb_channels;
     int64_t pts;
     AVExpr *expr[8];
     char *expr_str[8];
     int nb_samples;             ///< number of samples per requested frame

     char *duration_str;         ///< total duration of the generated audio
     double duration;

     uint64_t n;
     double var_values[VAR_VARS_NB];
 } EvalContext;
 
 #define OFFSET(x) offsetof(EvalContext, x)

 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

 static const AVOption aevalsrc_options[]= {

     { "nb_samples",  "set the number of samples per requested frame", OFFSET(nb_samples),      AV_OPT_TYPE_INT,    {.i64 = 1024},    0,        INT_MAX, FLAGS },
     { "n",           "set the number of samples per requested frame", OFFSET(nb_samples),      AV_OPT_TYPE_INT,    {.i64 = 1024},    0,        INT_MAX, FLAGS },

     { "sample_rate", "set the sample rate",                           OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "s",           "set the sample rate",                           OFFSET(sample_rate_str), AV_OPT_TYPE_STRING, {.str = "44100"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "duration",    "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
     { "d",           "set audio duration", OFFSET(duration_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
     { "channel_layout", "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },
     { "c",              "set channel layout", OFFSET(chlayout_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, FLAGS },

 {NULL},
 };
 

 AVFILTER_DEFINE_CLASS(aevalsrc);

 static int init(AVFilterContext *ctx, const char *args)

 {
     EvalContext *eval = ctx->priv;
     char *args1 = av_strdup(args);
     char *expr, *buf, *bufptr;
     int ret, i;
 

     eval->class = &aevalsrc_class;

     av_opt_set_defaults(eval);
 

     if (!args1) {
         av_log(ctx, AV_LOG_ERROR, "Argument is empty\n");
         ret = args ? AVERROR(ENOMEM) : AVERROR(EINVAL);
         goto end;
     }
 

     /* parse expressions */
     buf = args1;
     i = 0;

     while (expr = av_strtok(buf, ":", &bufptr)) {

         ret = av_expr_parse(&eval->expr[i], expr, var_names,
                             NULL, NULL, NULL, NULL, 0, ctx);
         if (ret < 0)
             goto end;
         i++;
         if (bufptr && *bufptr == ':') { /* found last expression */
             bufptr++;
             break;
         }
         buf = NULL;
     }

     eval->nb_channels = i;
 
     if (bufptr && (ret = av_set_options_string(eval, bufptr, "=", ":")) < 0)
         goto end;
 
     if (eval->chlayout_str) {
         int n;
         ret = ff_parse_channel_layout(&eval->chlayout, eval->chlayout_str, ctx);
         if (ret < 0)
             goto end;

         n = av_get_channel_layout_nb_channels(eval->chlayout);
         if (n != eval->nb_channels) {
             av_log(ctx, AV_LOG_ERROR,
                    "Mismatch between the specified number of channels '%d' "
                    "and the number of channels '%d' in the specified channel layout '%s'\n",
                    eval->nb_channels, n, eval->chlayout_str);
             ret = AVERROR(EINVAL);
             goto end;
         }
     } else {

         /* guess channel layout from nb expressions/channels */
         eval->chlayout = av_get_default_channel_layout(eval->nb_channels);
         if (!eval->chlayout) {
             av_log(ctx, AV_LOG_ERROR, "Invalid number of channels '%d' provided\n",
                    eval->nb_channels);
             ret = AVERROR(EINVAL);
             goto end;
         }

     }

 
     if ((ret = ff_parse_sample_rate(&eval->sample_rate, eval->sample_rate_str, ctx)))
         goto end;

 
     eval->duration = -1;
     if (eval->duration_str) {
         int64_t us = -1;
         if ((ret = av_parse_time(&us, eval->duration_str, 1)) < 0) {
             av_log(ctx, AV_LOG_ERROR, "Invalid duration: '%s'\n", eval->duration_str);
             goto end;
         }
         eval->duration = (double)us / 1000000;
     }

     eval->n = 0;
 
 end:
     av_free(args1);
     return ret;
 }
 
 static void uninit(AVFilterContext *ctx)
 {
     EvalContext *eval = ctx->priv;
     int i;
 
     for (i = 0; i < 8; i++) {
         av_expr_free(eval->expr[i]);
         eval->expr[i] = NULL;
     }

     av_freep(&eval->chlayout_str);

     av_freep(&eval->duration_str);

     av_freep(&eval->sample_rate_str);
 }
 
 static int config_props(AVFilterLink *outlink)
 {
     EvalContext *eval = outlink->src->priv;
     char buf[128];
 
     outlink->time_base = (AVRational){1, eval->sample_rate};
     outlink->sample_rate = eval->sample_rate;
 
     eval->var_values[VAR_S] = eval->sample_rate;
 
     av_get_channel_layout_string(buf, sizeof(buf), 0, eval->chlayout);
 

     av_log(outlink->src, AV_LOG_VERBOSE,

            "sample_rate:%d chlayout:%s duration:%f\n",
            eval->sample_rate, buf, eval->duration);

 
     return 0;
 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     EvalContext *eval = ctx->priv;

     static const enum AVSampleFormat sample_fmts[] = { AV_SAMPLE_FMT_DBLP, AV_SAMPLE_FMT_NONE };

     int64_t chlayouts[] = { eval->chlayout, -1 };

     int sample_rates[] = { eval->sample_rate, -1 };

     ff_set_common_formats (ctx, ff_make_format_list(sample_fmts));

     ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));

     ff_set_common_samplerates(ctx, ff_make_format_list(sample_rates));

 
     return 0;
 }
 
 static int request_frame(AVFilterLink *outlink)
 {
     EvalContext *eval = outlink->src->priv;
     AVFilterBufferRef *samplesref;
     int i, j;

     double t = eval->n * (double)1/eval->sample_rate;

     if (eval->duration >= 0 && t >= eval->duration)

         return AVERROR_EOF;

     samplesref = ff_get_audio_buffer(outlink, AV_PERM_WRITE, eval->nb_samples);

 
     /* evaluate expression for each single sample and for each channel */
     for (i = 0; i < eval->nb_samples; i++, eval->n++) {
         eval->var_values[VAR_N] = eval->n;
         eval->var_values[VAR_T] = eval->var_values[VAR_N] * (double)1/eval->sample_rate;
 
         for (j = 0; j < eval->nb_channels; j++) {

             *((double *) samplesref->extended_data[j] + i) =

                 av_expr_eval(eval->expr[j], eval->var_values, NULL);
         }
     }
 
     samplesref->pts = eval->pts;
     samplesref->pos = -1;
     samplesref->audio->sample_rate = eval->sample_rate;
     eval->pts += eval->nb_samples;
 

     ff_filter_frame(outlink, samplesref);

 
     return 0;
 }
 

 static const AVFilterPad aevalsrc_outputs[] = {
     {
         .name          = "default",
         .type          = AVMEDIA_TYPE_AUDIO,
         .config_props  = config_props,
         .request_frame = request_frame,
     },
     { NULL }
 };
 

 AVFilter avfilter_asrc_aevalsrc = {
     .name        = "aevalsrc",
     .description = NULL_IF_CONFIG_SMALL("Generate an audio signal generated by an expression."),
 
     .query_formats = query_formats,
     .init        = init,
     .uninit      = uninit,
     .priv_size   = sizeof(EvalContext),

     .inputs      = NULL,
     .outputs     = aevalsrc_outputs,
     .priv_class  = &aevalsrc_class,

 };