/*
  * filter graph parser

  * Copyright (c) 2008 Vitor Sessak
  * Copyright (c) 2007 Bobby Bingham

  *
  * 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 <ctype.h>
 #include <string.h>
 

 #include "libavutil/avstring.h"

 #include "avfilter.h"
 #include "avfiltergraph.h"
 

 #define WHITESPACES " \n\t"
 

 /**
  * Link two filters together.
  *
  * @see avfilter_link()
  */

 static int link_filter(AVFilterContext *src, int srcpad,

                        AVFilterContext *dst, int dstpad,

                        void *log_ctx)

 {

     int ret;
     if ((ret = avfilter_link(src, srcpad, dst, dstpad))) {

         av_log(log_ctx, AV_LOG_ERROR,

                "Cannot create the link %s:%d -> %s:%d\n",

                src->filter->name, srcpad, dst->filter->name, dstpad);

         return ret;

     }
 
     return 0;
 }
 
 /**

  * Parse the name of a link, which has the format "[linkname]".
  *
  * @return a pointer (that need to be freed after use) to the name
  * between parenthesis

  */

 static char *parse_link_name(const char **buf, void *log_ctx)

 {

     const char *start = *buf;

     char *name;

     (*buf)++;
 

     name = av_get_token(buf, "]");

     if (!name[0]) {

         av_log(log_ctx, AV_LOG_ERROR,

                "Bad (empty?) label found in the following: \"%s\".\n", start);

         goto fail;

     }

     if (*(*buf)++ != ']') {

         av_log(log_ctx, AV_LOG_ERROR,

                "Mismatched '[' found in the following: \"%s\".\n", start);

     fail:

         av_freep(&name);

     }

 
     return name;

 }
 

 /**
  * Create an instance of a filter, initialize and insert it in the
  * filtergraph in *ctx.
  *
  * @param ctx the filtergraph context

  * @param put here a filter context in case of successful creation and configuration, NULL otherwise.

  * @param index an index which is supposed to be unique for each filter instance added to the filtergraph
  * @param filt_name the name of the filter to create
  * @param args the arguments provided to the filter during its initialization
  * @param log_ctx the log context to use

  * @return 0 in case of success, a negative AVERROR code otherwise

  */

 static int create_filter(AVFilterContext **filt_ctx, AVFilterGraph *ctx, int index,

                          const char *filt_name, const char *args, void *log_ctx)

 {

     AVFilter *filt;

     char inst_name[30];

     char tmp_args[256];

     int ret;

     snprintf(inst_name, sizeof(inst_name), "Parsed filter %d %s", index, filt_name);

     filt = avfilter_get_by_name(filt_name);

     if (!filt) {

         av_log(log_ctx, AV_LOG_ERROR,

                "No such filter: '%s'\n", filt_name);

         return AVERROR(EINVAL);

     }
 

     ret = avfilter_open(filt_ctx, filt, inst_name);
     if (!*filt_ctx) {

         av_log(log_ctx, AV_LOG_ERROR,

                "Error creating filter '%s'\n", filt_name);

         return ret;

     }
 

     if ((ret = avfilter_graph_add_filter(ctx, *filt_ctx)) < 0) {

         avfilter_free(*filt_ctx);

         return ret;

     }

     if (!strcmp(filt_name, "scale") && args && !strstr(args, "flags")) {

         snprintf(tmp_args, sizeof(tmp_args), "%s:%s",
                  args, ctx->scale_sws_opts);
         args = tmp_args;
     }
 

     if ((ret = avfilter_init_filter(*filt_ctx, args, NULL)) < 0) {

         av_log(log_ctx, AV_LOG_ERROR,

                "Error initializing filter '%s' with args '%s'\n", filt_name, args);

         return ret;

     }
 

     return 0;

 }
 

 /**

  * Parse a string of the form FILTER_NAME[=PARAMS], and create a
  * corresponding filter instance which is added to graph with
  * create_filter().
  *
  * @param filt_ctx put here a pointer to the created filter context on
  * success, NULL otherwise
  * @param buf pointer to the buffer to parse, *buf will be updated to
  * point to the char next after the parsed string
  * @param index an index which is assigned to the created filter
  * instance, and which is supposed to be unique for each filter
  * instance added to the filtergraph
  * @return 0 in case of success, a negative AVERROR code otherwise

  */

 static int parse_filter(AVFilterContext **filt_ctx, const char **buf, AVFilterGraph *graph,

                         int index, void *log_ctx)

 {

     char *opts = NULL;

     char *name = av_get_token(buf, "=,;[\n");

     int ret;

     if (**buf == '=') {

         (*buf)++;

         opts = av_get_token(buf, "[],;\n");

     }

     ret = create_filter(filt_ctx, graph, index, name, opts, log_ctx);

     av_free(name);
     av_free(opts);

     return ret;

 }
 

 AVFilterInOut *avfilter_inout_alloc(void)

 {

     return av_mallocz(sizeof(AVFilterInOut));
 }
 
 void avfilter_inout_free(AVFilterInOut **inout)
 {
     while (*inout) {
         AVFilterInOut *next = (*inout)->next;
         av_freep(&(*inout)->name);
         av_freep(inout);
         *inout = next;

     }
 }
 

 static AVFilterInOut *extract_inout(const char *label, AVFilterInOut **links)
 {
     AVFilterInOut *ret;
 

     while (*links && strcmp((*links)->name, label))

         links = &((*links)->next);

     ret = *links;

     if (ret)

         *links = ret->next;

 
     return ret;
 }
 

 static void insert_inout(AVFilterInOut **inouts, AVFilterInOut *element)
 {
     element->next = *inouts;
     *inouts = element;
 }

 static int link_filter_inouts(AVFilterContext *filt_ctx,

                               AVFilterInOut **curr_inputs,

                               AVFilterInOut **open_inputs, void *log_ctx)

 {

     int pad = filt_ctx->input_count, ret;

     while (pad--) {

         AVFilterInOut *p = *curr_inputs;

         if (!p) {

             av_log(log_ctx, AV_LOG_ERROR,
                    "Not enough inputs specified for the \"%s\" filter.\n",

                    filt_ctx->filter->name);

             return AVERROR(EINVAL);

         }
 

         *curr_inputs = (*curr_inputs)->next;

         if (p->filter_ctx) {
             if ((ret = link_filter(p->filter_ctx, p->pad_idx, filt_ctx, pad, log_ctx)) < 0)

                 return ret;

             av_free(p->name);

             av_free(p);
         } else {

             p->filter_ctx = filt_ctx;

             p->pad_idx = pad;

             insert_inout(open_inputs, p);

         }
     }
 

     if (*curr_inputs) {

         av_log(log_ctx, AV_LOG_ERROR,
                "Too many inputs specified for the \"%s\" filter.\n",

                filt_ctx->filter->name);

         return AVERROR(EINVAL);

     }
 

     pad = filt_ctx->output_count;

     while (pad--) {

         AVFilterInOut *currlinkn = av_mallocz(sizeof(AVFilterInOut));

         if (!currlinkn)
             return AVERROR(ENOMEM);

         currlinkn->filter_ctx  = filt_ctx;

         currlinkn->pad_idx = pad;

         insert_inout(curr_inputs, currlinkn);

     }
 
     return 0;
 }
 

 static int parse_inputs(const char **buf, AVFilterInOut **curr_inputs,

                         AVFilterInOut **open_outputs, void *log_ctx)

 {

     int pad = 0;
 

     while (**buf == '[') {

         char *name = parse_link_name(buf, log_ctx);

         AVFilterInOut *match;

         if (!name)

             return AVERROR(EINVAL);

         /* First check if the label is not in the open_outputs list */
         match = extract_inout(name, open_outputs);

         if (match) {

             av_free(name);

         } else {
             /* Not in the list, so add it as an input */

             if (!(match = av_mallocz(sizeof(AVFilterInOut))))
                 return AVERROR(ENOMEM);

             match->name    = name;
             match->pad_idx = pad;

         }

         insert_inout(curr_inputs, match);

         *buf += strspn(*buf, WHITESPACES);

         pad++;

     }

     return pad;
 }
 

 static int parse_outputs(const char **buf, AVFilterInOut **curr_inputs,
                          AVFilterInOut **open_inputs,

                          AVFilterInOut **open_outputs, void *log_ctx)

 {

     int ret, pad = 0;

     while (**buf == '[') {

         char *name = parse_link_name(buf, log_ctx);

         AVFilterInOut *match;
 

         AVFilterInOut *input = *curr_inputs;

         if (!input) {
             av_log(log_ctx, AV_LOG_ERROR,
                    "No output pad can be associated to link label '%s'.\n",
                    name);
             return AVERROR(EINVAL);
         }

         *curr_inputs = (*curr_inputs)->next;

         if (!name)

             return AVERROR(EINVAL);

         /* First check if the label is not in the open_inputs list */
         match = extract_inout(name, open_inputs);

         if (match) {

             if ((ret = link_filter(input->filter_ctx, input->pad_idx,
                                    match->filter_ctx, match->pad_idx, log_ctx)) < 0)

                 return ret;

             av_free(match->name);
             av_free(name);

             av_free(match);

             av_free(input);

         } else {

             /* Not in the list, so add the first input as a open_output */

             input->name = name;

             insert_inout(open_outputs, input);

         }

         *buf += strspn(*buf, WHITESPACES);

         pad++;

     }

     return pad;
 }

 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,

                          AVFilterInOut **open_inputs, AVFilterInOut **open_outputs,
                          void *log_ctx)

 {

     int index = 0, ret;

     char chr = 0;
 

     AVFilterInOut *curr_inputs = NULL;

 
     do {

         AVFilterContext *filter;

         const char *filterchain = filters;

         filters += strspn(filters, WHITESPACES);

         if ((ret = parse_inputs(&filters, &curr_inputs, open_outputs, log_ctx)) < 0)

             goto fail;
 

         if ((ret = parse_filter(&filter, &filters, graph, index, log_ctx)) < 0)

             goto fail;
 

         if (filter->input_count == 1 && !curr_inputs && !index) {

             /* First input can be omitted if it is "[in]" */

             const char *tmp = "[in]";

             if ((ret = parse_inputs(&tmp, &curr_inputs, open_outputs, log_ctx)) < 0)

                 goto fail;
         }
 

         if ((ret = link_filter_inouts(filter, &curr_inputs, open_inputs, log_ctx)) < 0)

             goto fail;

         if ((ret = parse_outputs(&filters, &curr_inputs, open_inputs, open_outputs,

                                  log_ctx)) < 0)

             goto fail;
 

         filters += strspn(filters, WHITESPACES);

         chr = *filters++;
 

         if (chr == ';' && curr_inputs) {

             av_log(log_ctx, AV_LOG_ERROR,

                    "Invalid filterchain containing an unlabelled output pad: \"%s\"\n",
                    filterchain);

             ret = AVERROR(EINVAL);

             goto fail;

         }

         index++;

     } while (chr == ',' || chr == ';');

     if (chr) {

         av_log(log_ctx, AV_LOG_ERROR,
                "Unable to parse graph description substring: \"%s\"\n",
                filters - 1);

         ret = AVERROR(EINVAL);

         goto fail;
     }
 

     if (open_inputs && *open_inputs && !strcmp((*open_inputs)->name, "out") && curr_inputs) {

         /* Last output can be omitted if it is "[out]" */

         const char *tmp = "[out]";

         if ((ret = parse_outputs(&tmp, &curr_inputs, open_inputs, open_outputs,

                                  log_ctx)) < 0)

             goto fail;
     }
 
     return 0;
 
  fail:

     for (; graph->filter_count > 0; graph->filter_count--)
         avfilter_free(graph->filters[graph->filter_count - 1]);
     av_freep(&graph->filters);

     avfilter_inout_free(open_inputs);
     avfilter_inout_free(open_outputs);
     avfilter_inout_free(&curr_inputs);

     return ret;

 }