/*
  * Multipart JPEG format
  * Copyright (c) 2015 Luca Barbato
  *

  * 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/avstring.h"
 
 #include "avformat.h"
 #include "internal.h"
 
 static int get_line(AVIOContext *pb, char *line, int line_size)
 {
     int i = ff_get_line(pb, line, line_size);
 
     if (i > 1 && line[i - 2] == '\r')
         line[i - 2] = '\0';
 
     if (pb->error)
         return pb->error;
 
     if (pb->eof_reached)
         return AVERROR_EOF;
 
     return 0;
 }
 
 static int split_tag_value(char **tag, char **value, char *line)
 {
     char *p = line;
 
     while (*p != '\0' && *p != ':')
         p++;
     if (*p != ':')
         return AVERROR_INVALIDDATA;
 
     *p   = '\0';
     *tag = line;
 
     p++;
 
     while (av_isspace(*p))
         p++;
 
     *value = p;
 
     return 0;
 }
 
 static int check_content_type(char *line)
 {
     char *tag, *value;
     int ret = split_tag_value(&tag, &value, line);
 
     if (ret < 0)
         return ret;
 
     if (av_strcasecmp(tag, "Content-type") ||
         av_strcasecmp(value, "image/jpeg"))
         return AVERROR_INVALIDDATA;
 
     return 0;
 }
 
 static int mpjpeg_read_probe(AVProbeData *p)
 {
     AVIOContext *pb;
     char line[128] = { 0 };
     int ret = 0;
 

     if (p->buf_size < 2 || p->buf[0] != '-' || p->buf[1] != '-')
         return 0;
 

     pb = avio_alloc_context(p->buf, p->buf_size, 0, NULL, NULL, NULL, NULL);
     if (!pb)
         return AVERROR(ENOMEM);
 
     while (!pb->eof_reached) {
         ret = get_line(pb, line, sizeof(line));
         if (ret < 0)
             break;
 
         ret = check_content_type(line);
         if (!ret) {
             ret = AVPROBE_SCORE_MAX;
             break;
         }
     }

     av_free(pb);
 
     return ret;
 }
 
 static int mpjpeg_read_header(AVFormatContext *s)
 {
     AVStream *st;
     char boundary[70 + 2 + 1];
     int64_t pos = avio_tell(s->pb);
     int ret;
 
 
     ret = get_line(s->pb, boundary, sizeof(boundary));
     if (ret < 0)
         return ret;
 
     if (strncmp(boundary, "--", 2))
         return AVERROR_INVALIDDATA;
 
     st = avformat_new_stream(s, NULL);

     if (!st)
         return AVERROR(ENOMEM);

 
     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
     st->codec->codec_id   = AV_CODEC_ID_MJPEG;
 
     avpriv_set_pts_info(st, 60, 1, 25);
 
     avio_seek(s->pb, pos, SEEK_SET);
 
     return 0;
 }
 
 static int parse_content_length(const char *value)
 {
     long int val = strtol(value, NULL, 10);
 
     if (val == LONG_MIN || val == LONG_MAX)
         return AVERROR(errno);
     if (val > INT_MAX)
         return AVERROR(ERANGE);
     return val;
 }
 
 static int parse_multipart_header(AVFormatContext *s)
 {
     char line[128];
     int found_content_type = 0;
     int ret, size = -1;
 
     ret = get_line(s->pb, line, sizeof(line));
     if (ret < 0)
         return ret;
 
     if (strncmp(line, "--", 2))
         return AVERROR_INVALIDDATA;
 
     while (!s->pb->eof_reached) {
         char *tag, *value;
 
         ret = get_line(s->pb, line, sizeof(line));
         if (ret < 0)
             return ret;
 
         if (line[0] == '\0')
             break;
 
         ret = split_tag_value(&tag, &value, line);
         if (ret < 0)
             return ret;
 
         if (!av_strcasecmp(tag, "Content-type")) {
             if (av_strcasecmp(value, "image/jpeg")) {
                 av_log(s, AV_LOG_ERROR,
                        "Unexpected %s : %s\n",
                        tag, value);
                 return AVERROR_INVALIDDATA;
             } else
                 found_content_type = 1;
         } else if (!av_strcasecmp(tag, "Content-Length")) {
             size = parse_content_length(value);
             if (size < 0)
                 return size;
         }
     }
 
     if (!found_content_type || size < 0) {
         return AVERROR_INVALIDDATA;
     }
 
     return size;
 }
 
 static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     int ret;
     int size = parse_multipart_header(s);
 
     if (size < 0)
         return size;
 
     ret = av_get_packet(s->pb, pkt, size);
     if (ret < 0)
         return ret;
 
     // trailing empty line
     avio_skip(s->pb, 2);
 
     return 0;
 }
 
 AVInputFormat ff_mpjpeg_demuxer = {
     .name              = "mpjpeg",
     .long_name         = NULL_IF_CONFIG_SMALL("MIME multipart JPEG"),
     .mime_type         = "multipart/x-mixed-replace",
     .extensions        = "mjpg",
     .read_probe        = mpjpeg_read_probe,
     .read_header       = mpjpeg_read_header,
     .read_packet       = mpjpeg_read_packet,
 };