/*
  * MPEG-DASH ISO BMFF segmenter
  * Copyright (c) 2014 Martin Storsjo
  *
  * 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 "config.h"
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 
 #include "libavutil/avassert.h"
 #include "libavutil/avstring.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/rational.h"
 #include "libavutil/time_internal.h"
 
 #include "avc.h"
 #include "avformat.h"
 #include "avio_internal.h"
 #include "internal.h"
 #include "isom.h"
 #include "os_support.h"
 #include "url.h"
 #include "dash.h"
 
 static DASHTmplId dash_read_tmpl_id(const char *identifier, char *format_tag,
                                     size_t format_tag_size, const char **ptr) {
     const char *next_ptr;
     DASHTmplId id_type = DASH_TMPL_ID_UNDEFINED;
 
     if (av_strstart(identifier, "$$", &next_ptr)) {
         id_type = DASH_TMPL_ID_ESCAPE;
         *ptr = next_ptr;
     } else if (av_strstart(identifier, "$RepresentationID$", &next_ptr)) {
         id_type = DASH_TMPL_ID_REP_ID;
         // default to basic format, as $RepresentationID$ identifiers
         // are not allowed to have custom format-tags.
         av_strlcpy(format_tag, "%d", format_tag_size);
         *ptr = next_ptr;
     } else { // the following identifiers may have an explicit format_tag
         if (av_strstart(identifier, "$Number", &next_ptr))
             id_type = DASH_TMPL_ID_NUMBER;
         else if (av_strstart(identifier, "$Bandwidth", &next_ptr))
             id_type = DASH_TMPL_ID_BANDWIDTH;
         else if (av_strstart(identifier, "$Time", &next_ptr))
             id_type = DASH_TMPL_ID_TIME;
         else
             id_type = DASH_TMPL_ID_UNDEFINED;
 
         // next parse the dash format-tag and generate a c-string format tag
         // (next_ptr now points at the first '%' at the beginning of the format-tag)
         if (id_type != DASH_TMPL_ID_UNDEFINED) {
             const char *number_format = (id_type == DASH_TMPL_ID_TIME) ? PRId64 : "d";
             if (next_ptr[0] == '$') { // no dash format-tag
                 snprintf(format_tag, format_tag_size, "%%%s", number_format);
                 *ptr = &next_ptr[1];
             } else {
                 const char *width_ptr;
                 // only tolerate single-digit width-field (i.e. up to 9-digit width)
                 if (av_strstart(next_ptr, "%0", &width_ptr) &&
                     av_isdigit(width_ptr[0]) &&
                     av_strstart(&width_ptr[1], "d$", &next_ptr)) {
                     // yes, we're using a format tag to build format_tag.
                     snprintf(format_tag, format_tag_size, "%s%c%s", "%0", width_ptr[0], number_format);
                     *ptr = next_ptr;
                 } else {
                     av_log(NULL, AV_LOG_WARNING, "Failed to parse format-tag beginning with %s. Expected either a "
                                                  "closing '$' character or a format-string like '%%0[width]d', "
                                                  "where width must be a single digit\n", next_ptr);
                     id_type = DASH_TMPL_ID_UNDEFINED;
                 }
             }
         }
     }
     return id_type;
 }
 
 void ff_dash_fill_tmpl_params(char *dst, size_t buffer_size,
                                   const char *template, int rep_id,
                                   int number, int bit_rate,
                                   int64_t time) {
     int dst_pos = 0;
     const char *t_cur = template;
     while (dst_pos < buffer_size - 1 && *t_cur) {
         char format_tag[7]; // May be "%d", "%0Xd", or "%0Xlld" (for $Time$), where X is in [0-9]
         int n = 0;
         DASHTmplId id_type;
         const char *t_next = strchr(t_cur, '$'); // copy over everything up to the first '$' character
         if (t_next) {
             int num_copy_bytes = FFMIN(t_next - t_cur, buffer_size - dst_pos - 1);
             av_strlcpy(&dst[dst_pos], t_cur, num_copy_bytes + 1);
             // advance
             dst_pos += num_copy_bytes;
             t_cur = t_next;
         } else { // no more DASH identifiers to substitute - just copy the rest over and break
             av_strlcpy(&dst[dst_pos], t_cur, buffer_size - dst_pos);
             break;
         }
 
         if (dst_pos >= buffer_size - 1 || !*t_cur)
             break;
 
         // t_cur is now pointing to a '$' character
         id_type = dash_read_tmpl_id(t_cur, format_tag, sizeof(format_tag), &t_next);
         switch (id_type) {
         case DASH_TMPL_ID_ESCAPE:
             av_strlcpy(&dst[dst_pos], "$", 2);
             n = 1;
             break;
         case DASH_TMPL_ID_REP_ID:
             n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, rep_id);
             break;
         case DASH_TMPL_ID_NUMBER:
             n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, number);
             break;
         case DASH_TMPL_ID_BANDWIDTH:
             n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, bit_rate);
             break;
         case DASH_TMPL_ID_TIME:
             n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, time);
             break;
         case DASH_TMPL_ID_UNDEFINED:
             // copy over one byte and advance
             av_strlcpy(&dst[dst_pos], t_cur, 2);
             n = 1;
             t_next = &t_cur[1];
             break;
         }
         // t_next points just past the processed identifier
         // n is the number of bytes that were attempted to be written to dst
         // (may have failed to write all because buffer_size).
 
         // advance
         dst_pos += FFMIN(n, buffer_size - dst_pos - 1);
         t_cur = t_next;
     }
 }