/*
  * Concat URL protocol
  * Copyright (c) 2006 Steve Lhomme
  * Copyright (c) 2007 Wolfram Gloger
  * Copyright (c) 2010 Michele Orrù
  *
  * 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 "avformat.h"
 #include "libavutil/avstring.h"
 #include "libavutil/mem.h"

 #include "url.h"

 
 #define AV_CAT_SEPARATOR "|"
 
 struct concat_nodes {
     URLContext *uc;                ///< node's URLContext
     int64_t     size;              ///< url filesize
 };
 
 struct concat_data {
     struct concat_nodes *nodes;    ///< list of nodes to concat
     size_t               length;   ///< number of cat'ed nodes
     size_t               current;  ///< index of currently read node
 };
 
 static av_cold int concat_close(URLContext *h)
 {
     int err = 0;
     size_t i;
     struct concat_data  *data  = h->priv_data;
     struct concat_nodes *nodes = data->nodes;
 
     for (i = 0; i != data->length; i++)

         err |= ffurl_close(nodes[i].uc);

 
     av_freep(&data->nodes);
     av_freep(&h->priv_data);
 
     return err < 0 ? -1 : 0;
 }
 
 static av_cold int concat_open(URLContext *h, const char *uri, int flags)
 {
     char *node_uri = NULL, *tmp_uri;
     int err = 0;
     int64_t size;
     size_t  len, i;
     URLContext *uc;
     struct concat_data  *data;
     struct concat_nodes *nodes;
 
     av_strstart(uri, "concat:", &uri);
 
     /* creating data */
     if (!(data = av_mallocz(sizeof(*data))))
         return AVERROR(ENOMEM);
     h->priv_data = data;
 
     for (i = 0, len = 1; uri[i]; i++)
         if (uri[i] == *AV_CAT_SEPARATOR)
             /* integer overflow */
             if (++len == UINT_MAX / sizeof(*nodes)) {
                 av_freep(&h->priv_data);
                 return AVERROR(ENAMETOOLONG);
             }
 
     if (!(nodes = av_malloc(sizeof(*nodes) * len))) {
         av_freep(&h->priv_data);
         return AVERROR(ENOMEM);
     } else
         data->nodes = nodes;
 
     /* handle input */
     if (!*uri)
         err = AVERROR(ENOENT);
     for (i = 0; *uri; i++) {
         /* parsing uri */
         len = strcspn(uri, AV_CAT_SEPARATOR);
         if (!(tmp_uri = av_realloc(node_uri, len+1))) {
             err = AVERROR(ENOMEM);
             break;
         } else
             node_uri = tmp_uri;
         av_strlcpy(node_uri, uri, len+1);
         uri += len + strspn(uri+len, AV_CAT_SEPARATOR);
 
         /* creating URLContext */

         if ((err = ffurl_open(&uc, node_uri, flags)) < 0)

             break;
 
         /* creating size */

         if ((size = ffurl_size(uc)) < 0) {

             ffurl_close(uc);

             err = AVERROR(ENOSYS);
             break;
         }
 
         /* assembling */
         nodes[i].uc   = uc;
         nodes[i].size = size;
     }
     av_free(node_uri);
     data->length = i;
 
     if (err < 0)
         concat_close(h);
     else if (!(nodes = av_realloc(nodes, data->length * sizeof(*nodes)))) {
         concat_close(h);
         err = AVERROR(ENOMEM);
     } else
         data->nodes = nodes;
     return err;
 }
 
 static int concat_read(URLContext *h, unsigned char *buf, int size)
 {
     int result, total = 0;
     struct concat_data  *data  = h->priv_data;
     struct concat_nodes *nodes = data->nodes;
     size_t i = data->current;
 
     while (size > 0) {

         result = ffurl_read(nodes[i].uc, buf, size);

         if (result < 0)
             return total ? total : result;
         if (!result)
             if (i + 1 == data->length ||

                 ffurl_seek(nodes[++i].uc, 0, SEEK_SET) < 0)

                 break;
         total += result;
         buf   += result;
         size  -= result;
     }
     data->current = i;
     return total;
 }
 
 static int64_t concat_seek(URLContext *h, int64_t pos, int whence)
 {
     int64_t result;
     struct concat_data  *data  = h->priv_data;
     struct concat_nodes *nodes = data->nodes;
     size_t i;
 
     switch (whence) {
     case SEEK_END:
         for (i = data->length - 1;

              i && pos < -nodes[i].size;

              i--)

             pos += nodes[i].size;

         break;
     case SEEK_CUR:
         /* get the absolute position */
         for (i = 0; i != data->current; i++)
             pos += nodes[i].size;

         pos += ffurl_seek(nodes[i].uc, 0, SEEK_CUR);

         whence = SEEK_SET;
         /* fall through with the absolute position */
     case SEEK_SET:
         for (i = 0; i != data->length - 1 && pos >= nodes[i].size; i++)
             pos -= nodes[i].size;
         break;
     default:
         return AVERROR(EINVAL);
     }
 

     result = ffurl_seek(nodes[i].uc, pos, whence);

     if (result >= 0) {
         data->current = i;
         while (i)

             result += nodes[--i].size;

     }
     return result;
 }
 

 URLProtocol ff_concat_protocol = {

     .name      = "concat",
     .url_open  = concat_open,
     .url_read  = concat_read,
     .url_seek  = concat_seek,
     .url_close = concat_close,

 };