/*

 * 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 "libavutil/mem.h"

#include "libavutil/opt.h"

#include "avformat.h"

#include "demux.h"

#include "internal.h"

#include "avio_internal.h"

typedef struct MPJPEGDemuxContext {

    const AVClass *class;

    char       *boundary;

    char       *searchstr;

    int         searchstr_len;

    int         strict_mime_boundary;

} MPJPEGDemuxContext;

static void trim_right(char *p)

{

    char *end;

    if (!p || !*p)

        return;

    end = p + strlen(p);

    while (end > p && av_isspace(*(end-1)))

        *(--end) = '\0';

}

static int get_line(AVIOContext *pb, char *line, int line_size)

{

    ff_get_line(pb, line, line_size);

    if (pb->error)

        return pb->error;

    if (pb->eof_reached)

        return AVERROR_EOF;

    trim_right(line);

    return 0;

}

static int split_tag_value(char **tag, char **value, char *line)

{

    char *p = line;

    int  foundData = 0;

    *tag = NULL;

    *value = NULL;

    while (*p != '\0' && *p != ':') {

        if (!av_isspace(*p)) {

            foundData = 1;

        }

        p++;

    }

    if (*p != ':')

        return foundData ? AVERROR_INVALIDDATA : 0;

    *p   = '\0';

    *tag = line;

    trim_right(*tag);

    p++;

    while (av_isspace(*p))

        p++;

    *value = p;

    trim_right(*value);

    return 0;

}

static int parse_multipart_header(AVIOContext *pb,

                                    int* size,

                                    const char* expected_boundary,

                                    void *log_ctx);

static int mpjpeg_read_close(AVFormatContext *s)

{

    MPJPEGDemuxContext *mpjpeg = s->priv_data;

    av_freep(&mpjpeg->boundary);

    av_freep(&mpjpeg->searchstr);

    return 0;

}

static int mpjpeg_read_probe(const AVProbeData *p)

{

    FFIOContext pb;

    int ret = 0;

    int size = 0;

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

        return 0;

    ffio_init_read_context(&pb, p->buf, p->buf_size);

    ret = (parse_multipart_header(&pb.pub, &size, "--", NULL) >= 0) ? AVPROBE_SCORE_MAX : 0;

    return ret;

}

static int mpjpeg_read_header(AVFormatContext *s)

{

    AVStream *st;

    char boundary[70 + 2 + 1] = {0};

    int64_t pos = avio_tell(s->pb);

    int ret;

    do {

        ret = get_line(s->pb, boundary, sizeof(boundary));

        if (ret < 0)

            return ret;

    } while (!boundary[0]);

    if (strncmp(boundary, "--", 2))

        return AVERROR_INVALIDDATA;

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;

    st->codecpar->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(AVIOContext *pb,

                            int* size,

                            const char* expected_boundary,

                            void *log_ctx)

{

    char line[128];

    int found_content_type = 0;

    int ret;

    *size = -1;

    // get the CRLF as empty string

    ret = get_line(pb, line, sizeof(line));

    if (ret < 0)

        return ret;

    /* some implementation do not provide the required

     * initial CRLF (see rfc1341 7.2.1)

     */

    while (!line[0]) {

        ret = get_line(pb, line, sizeof(line));

        if (ret < 0)

            return ret;

    }

    if (!av_strstart(line, expected_boundary, NULL)) {

        if (log_ctx)

        av_log(log_ctx,

            AV_LOG_ERROR,

            "Expected boundary '%s' not found, instead found a line of %"SIZE_SPECIFIER" bytes\n",

            expected_boundary,

            strlen(line));

        return AVERROR_INVALIDDATA;

    }

    while (!pb->eof_reached) {

        char *tag, *value;

        ret = get_line(pb, line, sizeof(line));

        if (ret < 0) {

            if (ret == AVERROR_EOF)

                break;

            return ret;

        }

        if (line[0] == '\0')

            break;

        ret = split_tag_value(&tag, &value, line);

        if (ret < 0)

            return ret;

        if (value==NULL || tag==NULL)

            break;

        if (!av_strcasecmp(tag, "Content-type")) {

            if (av_strcasecmp(value, "image/jpeg")) {

                if (log_ctx)

                av_log(log_ctx, 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 )

                if (log_ctx)

                av_log(log_ctx, AV_LOG_WARNING,

                           "Invalid Content-Length value : %s\n",

                           value);

        }

    }

    return found_content_type ? 0 : AVERROR_INVALIDDATA;

}

static char* mpjpeg_get_boundary(AVIOContext* pb)

{

    uint8_t *mime_type = NULL;

    const char *start;

    const char *end;

    uint8_t *res = NULL;

    int     len;

    /* get MIME type, and skip to the first parameter */

    av_opt_get(pb, "mime_type", AV_OPT_SEARCH_CHILDREN, &mime_type);

    start = mime_type;

    while (start != NULL && *start != '\0') {

        start = strchr(start, ';');

        if (!start)

            break;

        start = start+1;

        while (av_isspace(*start))

            start++;

        if (av_stristart(start, "boundary=", &start)) {

            end = strchr(start, ';');

            if (end)

                len = end - start - 1;

            else

                len = strlen(start);

            /* some endpoints may enclose the boundary

              in Content-Type in quotes */

            if ( len>2 && *start == '"' && start[len-1] == '"' ) {

                start++;

                len -= 2;

            }

            res = av_strndup(start, len);

            break;

        }

    }

    av_freep(&mime_type);

    return res;

}

static int mpjpeg_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    int size;

    int ret;

    MPJPEGDemuxContext *mpjpeg = s->priv_data;

    if (mpjpeg->boundary == NULL) {

        uint8_t* boundary = NULL;

        if (mpjpeg->strict_mime_boundary) {

            boundary = mpjpeg_get_boundary(s->pb);

        }

        if (boundary != NULL) {

            mpjpeg->boundary = av_asprintf("--%s", boundary);

            mpjpeg->searchstr = av_asprintf("\r\n--%s\r\n", boundary);

            av_freep(&boundary);

        } else {

            mpjpeg->boundary = av_strdup("--");

            mpjpeg->searchstr = av_strdup("\r\n--");

        }

        if (!mpjpeg->boundary || !mpjpeg->searchstr) {

            av_freep(&mpjpeg->boundary);

            av_freep(&mpjpeg->searchstr);

            return AVERROR(ENOMEM);

        }

        mpjpeg->searchstr_len = strlen(mpjpeg->searchstr);

    }

    ret = parse_multipart_header(s->pb, &size, mpjpeg->boundary, s);

    if (ret < 0)

        return ret;

    if (size > 0) {

        /* size has been provided to us in MIME header */

        ret = av_get_packet(s->pb, pkt, size);

    } else {

        /* no size was given -- we read until the next boundary or end-of-file */

        int len;

        const int read_chunk = 2048;

        pkt->pos  = avio_tell(s->pb);

        while ((ret = ffio_ensure_seekback(s->pb, read_chunk)) >= 0 && /* we may need to return as much as all we've read back to the buffer */

               (ret = av_append_packet(s->pb, pkt, read_chunk)) >= 0) {

            /* scan the new data */

            char *start;

            len = ret;

            start = pkt->data + pkt->size - len;

            do {

                if (!memcmp(start, mpjpeg->searchstr, mpjpeg->searchstr_len)) {

                    // got the boundary! rewind the stream

                    avio_seek(s->pb, -len, SEEK_CUR);

                    pkt->size -= len;

                    return pkt->size;

                }

                len--;

                start++;

            } while (len >= mpjpeg->searchstr_len);

            avio_seek(s->pb, -len, SEEK_CUR);

            pkt->size -= len;

        }

        /* error or EOF occurred */

        if (ret == AVERROR_EOF) {

            ret = pkt->size > 0 ? pkt->size : AVERROR_EOF;

        }

    }

    return ret;

}

#define OFFSET(x) offsetof(MPJPEGDemuxContext, x)

#define DEC AV_OPT_FLAG_DECODING_PARAM

static const AVOption mpjpeg_options[] = {

    { "strict_mime_boundary",  "require MIME boundaries match", OFFSET(strict_mime_boundary), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, DEC },

    { NULL }

};

static const AVClass mpjpeg_demuxer_class = {

    .class_name     = "MPJPEG demuxer",

    .item_name      = av_default_item_name,

    .option         = mpjpeg_options,

    .version        = LIBAVUTIL_VERSION_INT,

};

const FFInputFormat ff_mpjpeg_demuxer = {

    .p.name            = "mpjpeg",

    .p.long_name       = NULL_IF_CONFIG_SMALL("MIME multipart JPEG"),

    .p.mime_type       = "multipart/x-mixed-replace",

    .p.extensions      = "mjpg",

    .p.priv_class      = &mpjpeg_demuxer_class,

    .p.flags           = AVFMT_NOTIMESTAMPS,

    .priv_data_size    = sizeof(MPJPEGDemuxContext),

    .read_probe        = mpjpeg_read_probe,

    .read_header       = mpjpeg_read_header,

    .read_packet       = mpjpeg_read_packet,

    .read_close        = mpjpeg_read_close,

};