/*
  * ID3v2 header writer
  *

  * 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 <stdint.h>

 #include "libavutil/avstring.h"

 #include "libavutil/dict.h"
 #include "libavutil/intreadwrite.h"
 #include "avformat.h"
 #include "avio.h"
 #include "id3v2.h"
 
 static void id3v2_put_size(AVFormatContext *s, int size)
 {
     avio_w8(s->pb, size >> 21 & 0x7f);
     avio_w8(s->pb, size >> 14 & 0x7f);
     avio_w8(s->pb, size >> 7  & 0x7f);
     avio_w8(s->pb, size       & 0x7f);
 }
 
 static int string_is_ascii(const uint8_t *str)
 {
     while (*str && *str < 128) str++;
     return !*str;
 }
 
 /**
  * Write a text frame with one (normal frames) or two (TXXX frames) strings
  * according to encoding (only UTF-8 or UTF-16+BOM supported).
  * @return number of bytes written or a negative error code.
  */
 static int id3v2_put_ttag(AVFormatContext *s, const char *str1, const char *str2,
                           uint32_t tag, enum ID3v2Encoding enc)
 {
     int len;
     uint8_t *pb;
     int (*put)(AVIOContext*, const char*);
     AVIOContext *dyn_buf;
     if (avio_open_dyn_buf(&dyn_buf) < 0)
         return AVERROR(ENOMEM);
 
     /* check if the strings are ASCII-only and use UTF16 only if
      * they're not */
     if (enc == ID3v2_ENCODING_UTF16BOM && string_is_ascii(str1) &&
         (!str2 || string_is_ascii(str2)))
         enc = ID3v2_ENCODING_ISO8859;
 
     avio_w8(dyn_buf, enc);
     if (enc == ID3v2_ENCODING_UTF16BOM) {
         avio_wl16(dyn_buf, 0xFEFF);      /* BOM */
         put = avio_put_str16le;
     } else
         put = avio_put_str;
 
     put(dyn_buf, str1);
     if (str2)
         put(dyn_buf, str2);
     len = avio_close_dyn_buf(dyn_buf, &pb);
 
     avio_wb32(s->pb, tag);
     id3v2_put_size(s, len);
     avio_wb16(s->pb, 0);
     avio_write(s->pb, pb, len);
 
     av_freep(&pb);
     return len + ID3v2_HEADER_SIZE;
 }
 
 static int id3v2_check_write_tag(AVFormatContext *s, AVDictionaryEntry *t, const char table[][4],
                                  enum ID3v2Encoding enc)
 {
     uint32_t tag;
     int i;
 
     if (t->key[0] != 'T' || strlen(t->key) != 4)
         return -1;
     tag = AV_RB32(t->key);
     for (i = 0; *table[i]; i++)
         if (tag == AV_RB32(table[i]))
             return id3v2_put_ttag(s, t->value, NULL, tag, enc);
     return -1;
 }
 

 static void id3v2_3_metadata_split_date(AVDictionary **pm)
 {
     AVDictionaryEntry *mtag = NULL;
     AVDictionary *dst = NULL;
     const char *key, *value;
     char year[5] = {0}, day_month[5] = {0};
     int i;
 
     while ((mtag = av_dict_get(*pm, "", mtag, AV_DICT_IGNORE_SUFFIX))) {
         key = mtag->key;

         if (!av_strcasecmp(key, "date")) {

             /* split date tag using "YYYY-MM-DD" format into year and month/day segments */
             value = mtag->value;
             i = 0;
             while (value[i] >= '0' && value[i] <= '9') i++;
             if (value[i] == '\0' || value[i] == '-') {
                 av_strlcpy(year, value, sizeof(year));
                 av_dict_set(&dst, "TYER", year, 0);
 
                 if (value[i] == '-' &&
                     value[i+1] >= '0' && value[i+1] <= '1' &&
                     value[i+2] >= '0' && value[i+2] <= '9' &&
                     value[i+3] == '-' &&
                     value[i+4] >= '0' && value[i+4] <= '3' &&
                     value[i+5] >= '0' && value[i+5] <= '9' &&
                     (value[i+6] == '\0' || value[i+6] == ' ')) {
                     snprintf(day_month, sizeof(day_month), "%.2s%.2s", value + i + 4, value + i + 1);
                     av_dict_set(&dst, "TDAT", day_month, 0);
                 }
             } else
                 av_dict_set(&dst, key, value, 0);
         } else
             av_dict_set(&dst, key, mtag->value, 0);
     }
     av_dict_free(pm);
     *pm = dst;
 }
 

 int ff_id3v2_write(struct AVFormatContext *s, int id3v2_version,
                    const char *magic)
 {
     int64_t size_pos, cur_pos;
     AVDictionaryEntry *t = NULL;
 
     int totlen = 0, enc = id3v2_version == 3 ? ID3v2_ENCODING_UTF16BOM :
                                                ID3v2_ENCODING_UTF8;
 
 
     avio_wb32(s->pb, MKBETAG(magic[0], magic[1], magic[2], id3v2_version));
     avio_w8(s->pb, 0);
     avio_w8(s->pb, 0); /* flags */
 
     /* reserve space for size */
     size_pos = avio_tell(s->pb);
     avio_wb32(s->pb, 0);
 
     ff_metadata_conv(&s->metadata, ff_id3v2_34_metadata_conv, NULL);

     if (id3v2_version == 3)
         id3v2_3_metadata_split_date(&s->metadata);
     else if (id3v2_version == 4)

         ff_metadata_conv(&s->metadata, ff_id3v2_4_metadata_conv, NULL);
 
     while ((t = av_dict_get(s->metadata, "", t, AV_DICT_IGNORE_SUFFIX))) {
         int ret;
 
         if ((ret = id3v2_check_write_tag(s, t, ff_id3v2_tags, enc)) > 0) {
             totlen += ret;
             continue;
         }
         if ((ret = id3v2_check_write_tag(s, t, id3v2_version == 3 ?
                                                ff_id3v2_3_tags : ff_id3v2_4_tags, enc)) > 0) {
             totlen += ret;
             continue;
         }
 
         /* unknown tag, write as TXXX frame */
         if ((ret = id3v2_put_ttag(s, t->key, t->value, MKBETAG('T', 'X', 'X', 'X'), enc)) < 0)
             return ret;
         totlen += ret;
     }
 
     cur_pos = avio_tell(s->pb);
     avio_seek(s->pb, size_pos, SEEK_SET);
     id3v2_put_size(s, totlen);
     avio_seek(s->pb, cur_pos, SEEK_SET);
     return 0;
 }