/* GStreamer

 * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>

 * Copyright (C) 2004 Ronald S. Bultje <rbultje@ronald.bitfreak.net>

 * Copyright (C) 2006 Tim-Philipp Müller <tim centricular net>

 * Copyright (C) 2016 Philippe Normand <pnormand@igalia.com>

 * Copyright (C) 2016 Jan Schmidt <jan@centricular.com>

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <glib.h>

#include "gstsubparse.h"

#include "gstssaparse.h"

#include "samiparse.h"

#include "tmplayerparse.h"

#include "mpl2parse.h"

#include "qttextparse.h"

GST_DEBUG_CATEGORY (sub_parse_debug);

#define DEFAULT_ENCODING   NULL

#define ATTRIBUTE_REGEX "\\s?[a-zA-Z0-9\\. \t\\(\\)]*"

static const gchar *allowed_srt_tags[] = { "i", "b", "u", NULL };

static const gchar *allowed_vtt_tags[] =

    { "i", "b", "c", "u", "v", "ruby", "rt", NULL };

enum

{

  PROP_0,

  PROP_ENCODING,

  PROP_VIDEOFPS

};

static void

gst_sub_parse_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec);

static void

gst_sub_parse_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec);

static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",

    GST_PAD_SINK,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("application/x-subtitle; application/x-subtitle-sami; "

        "application/x-subtitle-tmplayer; application/x-subtitle-mpl2; "

        "application/x-subtitle-dks; application/x-subtitle-qttext;"

        "application/x-subtitle-lrc; application/x-subtitle-vtt")

    );

static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",

    GST_PAD_SRC,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("text/x-raw, format= { pango-markup, utf8 }")

    );

static gboolean gst_sub_parse_src_event (GstPad * pad, GstObject * parent,

    GstEvent * event);

static gboolean gst_sub_parse_src_query (GstPad * pad, GstObject * parent,

    GstQuery * query);

static gboolean gst_sub_parse_sink_event (GstPad * pad, GstObject * parent,

    GstEvent * event);

static GstStateChangeReturn gst_sub_parse_change_state (GstElement * element,

    GstStateChange transition);

static GstFlowReturn gst_sub_parse_chain (GstPad * sinkpad, GstObject * parent,

    GstBuffer * buf);

#define gst_sub_parse_parent_class parent_class

G_DEFINE_TYPE (GstSubParse, gst_sub_parse, GST_TYPE_ELEMENT);

static void

gst_sub_parse_dispose (GObject * object)

{

  GstSubParse *subparse = GST_SUBPARSE (object);

  GST_DEBUG_OBJECT (subparse, "cleaning up subtitle parser");

  if (subparse->encoding) {

    g_free (subparse->encoding);

    subparse->encoding = NULL;

  }

  if (subparse->detected_encoding) {

    g_free (subparse->detected_encoding);

    subparse->detected_encoding = NULL;

  }

  if (subparse->adapter) {

    g_object_unref (subparse->adapter);

    subparse->adapter = NULL;

  }

  if (subparse->textbuf) {

    g_string_free (subparse->textbuf, TRUE);

    subparse->textbuf = NULL;

  }

  GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));

}

static void

gst_sub_parse_class_init (GstSubParseClass * klass)

{

  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

  object_class->dispose = gst_sub_parse_dispose;

  object_class->set_property = gst_sub_parse_set_property;

  object_class->get_property = gst_sub_parse_get_property;

  gst_element_class_add_static_pad_template (element_class, &sink_templ);

  gst_element_class_add_static_pad_template (element_class, &src_templ);

  gst_element_class_set_static_metadata (element_class,

      "Subtitle parser", "Codec/Parser/Subtitle",

      "Parses subtitle (.sub) files into text streams",

      "Gustavo J. A. M. Carneiro <gjc@inescporto.pt>, "

      "GStreamer maintainers <gstreamer-devel@lists.freedesktop.org>");

  element_class->change_state = gst_sub_parse_change_state;

  g_object_class_install_property (object_class, PROP_ENCODING,

      g_param_spec_string ("subtitle-encoding", "subtitle charset encoding",

          "Encoding to assume if input subtitles are not in UTF-8 or any other "

          "Unicode encoding. If not set, the GST_SUBTITLE_ENCODING environment "

          "variable will be checked for an encoding to use. If that is not set "

          "either, ISO-8859-15 will be assumed.", DEFAULT_ENCODING,

          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (object_class, PROP_VIDEOFPS,

      gst_param_spec_fraction ("video-fps", "Video framerate",

          "Framerate of the video stream. This is needed by some subtitle "

          "formats to synchronize subtitles and video properly. If not set "

          "and the subtitle format requires it subtitles may be out of sync.",

          0, 1, G_MAXINT, 1, 24000, 1001,

          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

}

static void

gst_sub_parse_init (GstSubParse * subparse)

{

  subparse->sinkpad = gst_pad_new_from_static_template (&sink_templ, "sink");

  gst_pad_set_chain_function (subparse->sinkpad,

      GST_DEBUG_FUNCPTR (gst_sub_parse_chain));

  gst_pad_set_event_function (subparse->sinkpad,

      GST_DEBUG_FUNCPTR (gst_sub_parse_sink_event));

  gst_element_add_pad (GST_ELEMENT (subparse), subparse->sinkpad);

  subparse->srcpad = gst_pad_new_from_static_template (&src_templ, "src");

  gst_pad_set_event_function (subparse->srcpad,

      GST_DEBUG_FUNCPTR (gst_sub_parse_src_event));

  gst_pad_set_query_function (subparse->srcpad,

      GST_DEBUG_FUNCPTR (gst_sub_parse_src_query));

  gst_element_add_pad (GST_ELEMENT (subparse), subparse->srcpad);

  subparse->textbuf = g_string_new (NULL);

  subparse->parser_type = GST_SUB_PARSE_FORMAT_UNKNOWN;

  subparse->flushing = FALSE;

  gst_segment_init (&subparse->segment, GST_FORMAT_TIME);

  subparse->need_segment = TRUE;

  subparse->encoding = g_strdup (DEFAULT_ENCODING);

  subparse->detected_encoding = NULL;

  subparse->adapter = gst_adapter_new ();

  subparse->fps_n = 24000;

  subparse->fps_d = 1001;

}

/*

 * Source pad functions.

 */

static gboolean

gst_sub_parse_src_query (GstPad * pad, GstObject * parent, GstQuery * query)

{

  GstSubParse *self = GST_SUBPARSE (parent);

  gboolean ret = FALSE;

  GST_DEBUG ("Handling %s query", GST_QUERY_TYPE_NAME (query));

  switch (GST_QUERY_TYPE (query)) {

    case GST_QUERY_POSITION:{

      GstFormat fmt;

      gst_query_parse_position (query, &fmt, NULL);

      if (fmt != GST_FORMAT_TIME) {

        ret = gst_pad_peer_query (self->sinkpad, query);

      } else {

        ret = TRUE;

        gst_query_set_position (query, GST_FORMAT_TIME, self->segment.position);

      }

      break;

    }

    case GST_QUERY_SEEKING:

    {

      GstFormat fmt;

      gboolean seekable = FALSE;

      ret = TRUE;

      gst_query_parse_seeking (query, &fmt, NULL, NULL, NULL);

      if (fmt == GST_FORMAT_TIME) {

        GstQuery *peerquery = gst_query_new_seeking (GST_FORMAT_BYTES);

        seekable = gst_pad_peer_query (self->sinkpad, peerquery);

        if (seekable)

          gst_query_parse_seeking (peerquery, NULL, &seekable, NULL, NULL);

        gst_query_unref (peerquery);

      }

      gst_query_set_seeking (query, fmt, seekable, seekable ? 0 : -1, -1);

      break;

    }

    default:

      ret = gst_pad_query_default (pad, parent, query);

      break;

  }

  return ret;

}

static gboolean

gst_sub_parse_src_event (GstPad * pad, GstObject * parent, GstEvent * event)

{

  GstSubParse *self = GST_SUBPARSE (parent);

  gboolean ret = FALSE;

  GST_DEBUG ("Handling %s event", GST_EVENT_TYPE_NAME (event));

  switch (GST_EVENT_TYPE (event)) {

    case GST_EVENT_SEEK:

    {

      GstFormat format;

      GstSeekFlags flags;

      GstSeekType start_type, stop_type;

      gint64 start, stop;

      gdouble rate;

      gboolean update;

      gst_event_parse_seek (event, &rate, &format, &flags,

          &start_type, &start, &stop_type, &stop);

      if (format != GST_FORMAT_TIME) {

        GST_WARNING_OBJECT (self, "we only support seeking in TIME format");

        gst_event_unref (event);

        goto beach;

      }

      /* Convert that seek to a seeking in bytes at position 0,

         FIXME: could use an index */

      ret = gst_pad_push_event (self->sinkpad,

          gst_event_new_seek (rate, GST_FORMAT_BYTES, flags,

              GST_SEEK_TYPE_SET, 0, GST_SEEK_TYPE_NONE, 0));

      if (ret) {

        /* Apply the seek to our segment */

        gst_segment_do_seek (&self->segment, rate, format, flags,

            start_type, start, stop_type, stop, &update);

        GST_DEBUG_OBJECT (self, "segment after seek: %" GST_SEGMENT_FORMAT,

            &self->segment);

        /* will mark need_segment when receiving segment from upstream,

         * after FLUSH and all that has happened,

         * rather than racing with chain */

      } else {

        GST_WARNING_OBJECT (self, "seek to 0 bytes failed");

      }

      gst_event_unref (event);

      break;

    }

    default:

      ret = gst_pad_event_default (pad, parent, event);

      break;

  }

beach:

  return ret;

}

static void

gst_sub_parse_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec)

{

  GstSubParse *subparse = GST_SUBPARSE (object);

  GST_OBJECT_LOCK (subparse);

  switch (prop_id) {

    case PROP_ENCODING:

      g_free (subparse->encoding);

      subparse->encoding = g_value_dup_string (value);

      GST_LOG_OBJECT (object, "subtitle encoding set to %s",

          GST_STR_NULL (subparse->encoding));

      break;

    case PROP_VIDEOFPS:

    {

      subparse->fps_n = gst_value_get_fraction_numerator (value);

      subparse->fps_d = gst_value_get_fraction_denominator (value);

      GST_DEBUG_OBJECT (object, "video framerate set to %d/%d", subparse->fps_n,

          subparse->fps_d);

      if (!subparse->state.have_internal_fps) {

        subparse->state.fps_n = subparse->fps_n;

        subparse->state.fps_d = subparse->fps_d;

      }

      break;

    }

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

  GST_OBJECT_UNLOCK (subparse);

}

static void

gst_sub_parse_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec)

{

  GstSubParse *subparse = GST_SUBPARSE (object);

  GST_OBJECT_LOCK (subparse);

  switch (prop_id) {

    case PROP_ENCODING:

      g_value_set_string (value, subparse->encoding);

      break;

    case PROP_VIDEOFPS:

      gst_value_set_fraction (value, subparse->fps_n, subparse->fps_d);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

  GST_OBJECT_UNLOCK (subparse);

}

static const gchar *

gst_sub_parse_get_format_description (GstSubParseFormat format)

{

  switch (format) {

    case GST_SUB_PARSE_FORMAT_MDVDSUB:

      return "MicroDVD";

    case GST_SUB_PARSE_FORMAT_SUBRIP:

      return "SubRip";

    case GST_SUB_PARSE_FORMAT_MPSUB:

      return "MPSub";

    case GST_SUB_PARSE_FORMAT_SAMI:

      return "SAMI";

    case GST_SUB_PARSE_FORMAT_TMPLAYER:

      return "TMPlayer";

    case GST_SUB_PARSE_FORMAT_MPL2:

      return "MPL2";

    case GST_SUB_PARSE_FORMAT_SUBVIEWER:

      return "SubViewer";

    case GST_SUB_PARSE_FORMAT_DKS:

      return "DKS";

    case GST_SUB_PARSE_FORMAT_VTT:

      return "WebVTT";

    case GST_SUB_PARSE_FORMAT_QTTEXT:

      return "QTtext";

    case GST_SUB_PARSE_FORMAT_LRC:

      return "LRC";

    default:

    case GST_SUB_PARSE_FORMAT_UNKNOWN:

      break;

  }

  return NULL;

}

static gchar *

gst_convert_to_utf8 (const gchar * str, gsize len, const gchar * encoding,

    gsize * consumed, GError ** err)

{

  gchar *ret = NULL;

  *consumed = 0;

  /* The char cast is necessary in glib < 2.24 */

  ret =

      g_convert_with_fallback (str, len, "UTF-8", encoding, (char *) "*",

      consumed, NULL, err);

  if (ret == NULL)

    return ret;

  /* + 3 to skip UTF-8 BOM if it was added */

  len = strlen (ret);

  if (len >= 3 && (guint8) ret[0] == 0xEF && (guint8) ret[1] == 0xBB

      && (guint8) ret[2] == 0xBF)

    memmove (ret, ret + 3, len + 1 - 3);

  return ret;

}

static gchar *

detect_encoding (const gchar * str, gsize len)

{

  if (len >= 3 && (guint8) str[0] == 0xEF && (guint8) str[1] == 0xBB

      && (guint8) str[2] == 0xBF)

    return g_strdup ("UTF-8");

  if (len >= 2 && (guint8) str[0] == 0xFE && (guint8) str[1] == 0xFF)

    return g_strdup ("UTF-16BE");

  if (len >= 2 && (guint8) str[0] == 0xFF && (guint8) str[1] == 0xFE)

    return g_strdup ("UTF-16LE");

  if (len >= 4 && (guint8) str[0] == 0x00 && (guint8) str[1] == 0x00

      && (guint8) str[2] == 0xFE && (guint8) str[3] == 0xFF)

    return g_strdup ("UTF-32BE");

  if (len >= 4 && (guint8) str[0] == 0xFF && (guint8) str[1] == 0xFE

      && (guint8) str[2] == 0x00 && (guint8) str[3] == 0x00)

    return g_strdup ("UTF-32LE");

  return NULL;

}

static gchar *

convert_encoding (GstSubParse * self, const gchar * str, gsize len,

    gsize * consumed)

{

  const gchar *encoding;

  GError *err = NULL;

  gchar *ret = NULL;

  *consumed = 0;

  /* First try any detected encoding */

  if (self->detected_encoding) {

    ret =

        gst_convert_to_utf8 (str, len, self->detected_encoding, consumed, &err;;

    if (!err)

      return ret;

    GST_WARNING_OBJECT (self, "could not convert string from '%s' to UTF-8: %s",

        self->detected_encoding, err->message);

    g_free (self->detected_encoding);

    self->detected_encoding = NULL;

    g_clear_error (&err;;

  }

  /* Otherwise check if it's UTF8 */

  if (self->valid_utf8) {

    if (g_utf8_validate (str, len, NULL)) {

      GST_LOG_OBJECT (self, "valid UTF-8, no conversion needed");

      *consumed = len;

      return g_strndup (str, len);

    }

    GST_INFO_OBJECT (self, "invalid UTF-8!");

    self->valid_utf8 = FALSE;

  }

  /* Else try fallback */

  encoding = self->encoding;

  if (encoding == NULL || *encoding == '\0') {

    encoding = g_getenv ("GST_SUBTITLE_ENCODING");

  }

  if (encoding == NULL || *encoding == '\0') {

    /* if local encoding is UTF-8 and no encoding specified

     * via the environment variable, assume ISO-8859-15 */

    if (g_get_charset (&encoding)) {

      encoding = "ISO-8859-15";

    }

  }

  ret = gst_convert_to_utf8 (str, len, encoding, consumed, &err;;

  if (err) {

    GST_WARNING_OBJECT (self, "could not convert string from '%s' to UTF-8: %s",

        encoding, err->message);

    g_clear_error (&err;;

    /* invalid input encoding, fall back to ISO-8859-15 (always succeeds) */

    ret = gst_convert_to_utf8 (str, len, "ISO-8859-15", consumed, NULL);

  }

  GST_LOG_OBJECT (self,

      "successfully converted %" G_GSIZE_FORMAT " characters from %s to UTF-8"

      "%s", len, encoding, (err) ? " , using ISO-8859-15 as fallback" : "");

  return ret;

}

static gchar *

get_next_line (GstSubParse * self)

{

  char *line = NULL;

  const char *line_end;

  int line_len;

  gboolean have_r = FALSE;

  line_end = strchr (self->textbuf->str, '\n');

  if (!line_end) {

    /* end-of-line not found; return for more data */

    return NULL;

  }

  /* get rid of '\r' */

  if (line_end != self->textbuf->str && *(line_end - 1) == '\r') {

    line_end--;

    have_r = TRUE;

  }

  line_len = line_end - self->textbuf->str;

  line = g_strndup (self->textbuf->str, line_len);

  self->textbuf = g_string_erase (self->textbuf, 0,

      line_len + (have_r ? 2 : 1));

  return line;

}

static gchar *

parse_mdvdsub (ParserState * state, const gchar * line)

{

  const gchar *line_split;

  gchar *line_chunk;

  guint start_frame, end_frame;

  guint64 clip_start = 0, clip_stop = 0;

  gboolean in_seg = FALSE;

  GString *markup;

  gchar *ret;

  /* style variables */

  gboolean italic;

  gboolean bold;

  guint fontsize;

  gdouble fps = 0.0;

  if (sscanf (line, "{%u}{%u}", &start_frame, &end_frame) != 2) {

    g_warning ("Parse of the following line, assumed to be in microdvd .sub"

        " format, failed:\n%s", line);

    return NULL;

  }

  /* skip the {%u}{%u} part */

  line = strchr (line, '}') + 1;

  line = strchr (line, '}') + 1;

  /* see if there's a first line with a framerate */

  if (start_frame == 1 && end_frame == 1) {

    gchar *rest, *end = NULL;

    rest = g_strdup (line);

    g_strdelimit (rest, ",", '.');

    fps = g_ascii_strtod (rest, &end;;

    if (end != rest) {

      gst_util_double_to_fraction (fps, &state->fps_n, &state->fps_d);

      GST_INFO ("framerate from file: %d/%d ('%s')", state->fps_n,

          state->fps_d, rest);

    }

    g_free (rest);

    return NULL;

  }

  state->start_time =

      gst_util_uint64_scale (start_frame, GST_SECOND * state->fps_d,

      state->fps_n);

  state->duration =

      gst_util_uint64_scale (end_frame - start_frame, GST_SECOND * state->fps_d,

      state->fps_n);

  /* Check our segment start/stop */

  in_seg = gst_segment_clip (state->segment, GST_FORMAT_TIME,

      state->start_time, state->start_time + state->duration, &clip_start,

      &clip_stop);

  /* No need to parse that text if it's out of segment */

  if (in_seg) {

    state->start_time = clip_start;

    state->duration = clip_stop - clip_start;

  } else {

    return NULL;

  }

  markup = g_string_new (NULL);

  while (1) {

    italic = FALSE;

    bold = FALSE;

    fontsize = 0;

    /* parse style markup */

    if (strncmp (line, "{y:i}", 5) == 0) {

      italic = TRUE;

      line = strchr (line, '}') + 1;

    }

    if (strncmp (line, "{y:b}", 5) == 0) {

      bold = TRUE;

      line = strchr (line, '}') + 1;

    }

    if (sscanf (line, "{s:%u}", &fontsize) == 1) {

      line = strchr (line, '}') + 1;

    }

    /* forward slashes at beginning/end signify italics too */

    if (g_str_has_prefix (line, "/")) {

      italic = TRUE;

      ++line;

    }

    if ((line_split = strchr (line, '|')))

      line_chunk = g_markup_escape_text (line, line_split - line);

    else

      line_chunk = g_markup_escape_text (line, strlen (line));

    /* Remove italics markers at end of line/stanza (CHECKME: are end slashes

     * always at the end of a line or can they span multiple lines?) */

    if (g_str_has_suffix (line_chunk, "/")) {

      line_chunk[strlen (line_chunk) - 1] = '\0';

    }

    markup = g_string_append (markup, "

    if (italic)

      g_string_append (markup, " style=\"italic\"");

    if (bold)

      g_string_append (markup, " weight=\"bold\"");

    if (fontsize)

      g_string_append_printf (markup, " size=\"%u\"", fontsize * 1000);

    g_string_append_printf (markup, ">%s", line_chunk);

    g_free (line_chunk);

    if (line_split) {

      g_string_append (markup, "\n");

      line = line_split + 1;

    } else {

      break;

    }

  }

  ret = markup->str;

  g_string_free (markup, FALSE);

  GST_DEBUG ("parse_mdvdsub returning (%f+%f): %s",

      state->start_time / (double) GST_SECOND,

      state->duration / (double) GST_SECOND, ret);

  return ret;

}

static void

strip_trailing_newlines (gchar * txt)

{

  if (txt) {

    guint len;

    len = strlen (txt);

    while (len > 1 && txt[len - 1] == '\n') {

      txt[len - 1] = '\0';

      --len;

    }

  }

}

/* we want to escape text in general, but retain basic markup like

 * , <u></u>, and . The easiest and safest way is to

 * just unescape a white list of allowed markups again after

 * escaping everything (the text between these simple markers isn't

 * necessarily escaped, so it seems best to do it like this) */

static void

subrip_unescape_formatting (gchar * txt, gconstpointer allowed_tags_ptr,

    gboolean allows_tag_attributes)

{

  gchar *res;

  GRegex *tag_regex;

  gchar *allowed_tags_pattern, *search_pattern;

  const gchar *replace_pattern;

  /* No processing needed if no escaped tag marker found in the string. */

  if (strstr (txt, "<") == NULL)

    return;

  /* Build a list of alternates for our regexp.

   * FIXME: Could be built once and stored */

  allowed_tags_pattern = g_strjoinv ("|", (gchar **) allowed_tags_ptr);

  /* Look for starting/ending escaped tags with optional attributes. */

  search_pattern = g_strdup_printf ("<(/)?\\ *(%s)(%s)>",

      allowed_tags_pattern, ATTRIBUTE_REGEX);

  /* And unescape appropriately */

  if (allows_tag_attributes) {

    replace_pattern = "<\\1\\2\\3>";

  } else {

    replace_pattern = "<\\1\\2>";

  }

  tag_regex = g_regex_new (search_pattern, 0, 0, NULL);

  res = g_regex_replace (tag_regex, txt, strlen (txt), 0,

      replace_pattern, 0, NULL);

  /* res will always be shorter than the input or identical, so this

   * copy is OK */

  strcpy (txt, res);

  g_free (res);

  g_free (search_pattern);

  g_free (allowed_tags_pattern);

  g_regex_unref (tag_regex);

}

static gboolean

subrip_remove_unhandled_tag (gchar * start, gchar * stop)

{

  gchar *tag, saved;

  tag = start + strlen ("<");

  if (*tag == '/')

    ++tag;

  if (g_ascii_tolower (*tag) < 'a' || g_ascii_tolower (*tag) > 'z')

    return FALSE;

  saved = *stop;

  *stop = '\0';

  GST_LOG ("removing unhandled tag '%s'", start);

  *stop = saved;

  memmove (start, stop, strlen (stop) + 1);

  return TRUE;

}

/* remove tags we haven't explicitly allowed earlier on, like font tags

 * for example */

static void

subrip_remove_unhandled_tags (gchar * txt)

{

  gchar *pos, *gt;

  for (pos = txt; pos != NULL && *pos != '\0'; ++pos) {

    if (strncmp (pos, "<", 4) == 0 && (gt = strstr (pos + 4, ">"))) {

      if (subrip_remove_unhandled_tag (pos, gt + strlen (">")))

        --pos;

    }

  }

}

/* we only allow a fixed set of tags like , <u> and , so let's

 * take a simple approach. This code assumes the input has been

 * escaped and subrip_unescape_formatting() has then been run over the

 * input! This function adds missing closing markup tags and removes

 * broken closing tags for tags that have never been opened. */

static void

subrip_fix_up_markup (gchar ** p_txt, gconstpointer allowed_tags_ptr)

{

  gchar *cur, *next_tag;

  GPtrArray *open_tags = NULL;

  guint num_open_tags = 0;

  const gchar *iter_tag;

  guint offset = 0;

  guint index;

  gchar *cur_tag;

  gchar *end_tag;

  GRegex *tag_regex;

  GMatchInfo *match_info;

  gchar **allowed_tags = (gchar **) allowed_tags_ptr;

  g_assert (*p_txt != NULL);

  open_tags = g_ptr_array_new_with_free_func (g_free);

  cur = *p_txt;

  while (*cur != '\0') {

    next_tag = strchr (cur, '<');

    if (next_tag == NULL)

      break;

    offset = 0;

    index = 0;

    while (index < g_strv_length (allowed_tags)) {

      iter_tag = allowed_tags[index];

      /* Look for a white listed tag */

      cur_tag = g_strconcat ("<", iter_tag, ATTRIBUTE_REGEX, ">", NULL);

      tag_regex = g_regex_new (cur_tag, 0, 0, NULL);

      (void) g_regex_match (tag_regex, next_tag, 0, &match_info);

      if (g_match_info_matches (match_info)) {

        gint start_pos, end_pos;

        gchar *word = g_match_info_fetch (match_info, 0);

        g_match_info_fetch_pos (match_info, 0, &start_pos, &end_pos);

        if (start_pos == 0) {

          offset = strlen (word);

        }

        g_free (word);

      }

      g_match_info_free (match_info);

      g_regex_unref (tag_regex);

      g_free (cur_tag);

      index++;

      if (offset) {

        /* OK we found a tag, let's keep track of it */

        g_ptr_array_add (open_tags, g_ascii_strdown (iter_tag, -1));

        ++num_open_tags;

        break;

      }

    }

    if (offset) {

      next_tag += offset;

      cur = next_tag;

      continue;

    }

    if (*next_tag == '<' && *(next_tag + 1) == '/') {

      end_tag = strchr (cur, '>');

      if (end_tag) {

        const gchar *last = g_ptr_array_index (open_tags, num_open_tags - 1);

        if (num_open_tags == 0

            || g_ascii_strncasecmp (end_tag - 1, last, strlen (last))) {

          GST_LOG ("broken input, closing tag '%s' is not open", end_tag - 1);

          memmove (next_tag, end_tag + 1, strlen (end_tag) + 1);

          next_tag -= strlen (end_tag);

        } else {

          --num_open_tags;

          g_ptr_array_remove_index (open_tags, num_open_tags);

        }

      }

    }

    ++next_tag;

    cur = next_tag;

  }

  if (num_open_tags > 0) {

    GString *s;

    s = g_string_new (*p_txt);

    while (num_open_tags > 0) {

      GST_LOG ("adding missing closing tag '%s'",

          (char *) g_ptr_array_index (open_tags, num_open_tags - 1));

      g_string_append_c (s, '<');

      g_string_append_c (s, '/');

      g_string_append (s, g_ptr_array_index (open_tags, num_open_tags - 1));

      g_string_append_c (s, '>');

      --num_open_tags;

    }

    g_free (*p_txt);

    *p_txt = g_string_free (s, FALSE);

  }

  g_ptr_array_free (open_tags, TRUE);

}

static gboolean

parse_subrip_time (const gchar * ts_string, GstClockTime * t)

{

  gchar s[128] = { '\0', };

  gchar *end, *p;

  guint hour, min, sec, msec, len;

  while (*ts_string == ' ')

    ++ts_string;

  g_strlcpy (s, ts_string, sizeof (s));

  if ((end = strstr (s, "-->")))

    *end = '\0';

  g_strchomp (s);

  /* ms may be in these formats:

   * hh:mm:ss,500 = 500ms

   * hh:mm:ss,  5 =   5ms

   * hh:mm:ss, 5  =  50ms

   * hh:mm:ss, 50 =  50ms

   * hh:mm:ss,5   = 500ms

   * and the same with . instead of ,.

   * sscanf() doesn't differentiate between '  5' and '5' so munge

   * the white spaces within the timestamp to '0' (I'm sure there's a

   * way to make sscanf() do this for us, but how?)

   */