/* GStreamer SSA subtitle parser

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

 *

 * 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., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/* Super-primitive SSA parser - we just want the text and ignore

 * everything else like styles and timing codes etc. for now */

#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <stdlib.h>             /* atoi() */

#include <string.h>

#include "gstssaparse.h"

GST_DEBUG_CATEGORY_STATIC (ssa_parse_debug);

#define GST_CAT_DEFAULT ssa_parse_debug

static GstStaticPadTemplate sink_templ = GST_STATIC_PAD_TEMPLATE ("sink",

    GST_PAD_SINK,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("application/x-ssa; application/x-ass")

    );

static GstStaticPadTemplate src_templ = GST_STATIC_PAD_TEMPLATE ("src",

    GST_PAD_SRC,

    GST_PAD_ALWAYS,

    GST_STATIC_CAPS ("text/x-pango-markup")

    );

GST_BOILERPLATE (GstSsaParse, gst_ssa_parse, GstElement, GST_TYPE_ELEMENT);

static GstStateChangeReturn gst_ssa_parse_change_state (GstElement *

    element, GstStateChange transition);

static gboolean gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps);

static gboolean gst_ssa_parse_src_event (GstPad * pad, GstEvent * event);

static gboolean gst_ssa_parse_sink_event (GstPad * pad, GstEvent * event);

static GstFlowReturn gst_ssa_parse_chain (GstPad * sinkpad, GstBuffer * buf);

static void

gst_ssa_parse_base_init (gpointer klass)

{

  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

  static GstElementDetails ssa_parse_details = {

    "SSA Subtitle Parser",

    "Codec/Parser/Subtitle",

    "Parses SSA subtitle streams",

    "Tim-Philipp Müller <tim centricular net>"

  };

  gst_element_class_add_pad_template (element_class,

      gst_static_pad_template_get (&sink_templ));

  gst_element_class_add_pad_template (element_class,

      gst_static_pad_template_get (&src_templ));

  gst_element_class_set_details (element_class, &ssa_parse_details);

  GST_DEBUG_CATEGORY_INIT (ssa_parse_debug, "ssaparse", 0,

      "SSA subtitle parser");

}

static void

gst_ssa_parse_dispose (GObject * object)

{

  GstSsaParse *parse = GST_SSA_PARSE (object);

  g_free (parse->ini);

  parse->ini = NULL;

  GST_CALL_PARENT (G_OBJECT_CLASS, dispose, (object));

}

static void

gst_ssa_parse_init (GstSsaParse * parse, GstSsaParseClass * klass)

{

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

  gst_pad_set_setcaps_function (parse->sinkpad,

      GST_DEBUG_FUNCPTR (gst_ssa_parse_setcaps));

  gst_pad_set_chain_function (parse->sinkpad,

      GST_DEBUG_FUNCPTR (gst_ssa_parse_chain));

  gst_pad_set_event_function (parse->sinkpad,

      GST_DEBUG_FUNCPTR (gst_ssa_parse_sink_event));

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

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

  gst_pad_set_event_function (parse->srcpad,

      GST_DEBUG_FUNCPTR (gst_ssa_parse_src_event));

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

  gst_pad_use_fixed_caps (parse->srcpad);

  gst_pad_set_caps (parse->srcpad,

      gst_static_pad_template_get_caps (&src_templ));

  parse->ini = NULL;

  parse->framed = FALSE;

}

static void

gst_ssa_parse_class_init (GstSsaParseClass * klass)

{

  GObjectClass *object_class = G_OBJECT_CLASS (klass);

  GstElementClass *element_class = GST_ELEMENT_CLASS (klass);

  object_class->dispose = GST_DEBUG_FUNCPTR (gst_ssa_parse_dispose);

  element_class->change_state = GST_DEBUG_FUNCPTR (gst_ssa_parse_change_state);

}

static gboolean

gst_ssa_parse_src_event (GstPad * pad, GstEvent * event)

{

  return gst_pad_event_default (pad, event);

}

static gboolean

gst_ssa_parse_sink_event (GstPad * pad, GstEvent * event)

{

  return gst_pad_event_default (pad, event);

}

static gboolean

gst_ssa_parse_setcaps (GstPad * sinkpad, GstCaps * caps)

{

  GstSsaParse *parse = GST_SSA_PARSE (GST_PAD_PARENT (sinkpad));

  const GValue *val;

  GstStructure *s;

  const guchar bom_utf8[] = { 0xEF, 0xBB, 0xBF };

  GstBuffer *priv;

  gchar *data;

  guint size;

  s = gst_caps_get_structure (caps, 0);

  val = gst_structure_get_value (s, "codec_data");

  if (val == NULL) {

    parse->framed = FALSE;

    GST_ERROR ("Only SSA subtitles embedded in containers are supported");

    return FALSE;

  }

  parse->framed = TRUE;

  priv = (GstBuffer *) gst_value_get_mini_object (val);

  g_return_val_if_fail (priv != NULL, FALSE);

  gst_buffer_ref (priv);

  data = (gchar *) GST_BUFFER_DATA (priv);

  size = GST_BUFFER_SIZE (priv);

  /* skip UTF-8 BOM */

  if (size >= 3 && memcmp (data, bom_utf8, 3) == 0) {

    data += 3;

    size -= 3;

  }

  if (!strstr (data, "[Script Info]")) {

    GST_WARNING_OBJECT (parse, "Invalid Init section - no Script Info header");

    gst_buffer_unref (priv);

    return FALSE;

  }

  if (!g_utf8_validate (data, size, NULL)) {

    GST_WARNING_OBJECT (parse, "Init section is not valid UTF-8");

    gst_buffer_unref (priv);

    return FALSE;

  }

  /* FIXME: parse initial section */

  parse->ini = g_strndup (data, size);

  GST_LOG_OBJECT (parse, "Init section:\n%s", parse->ini);

  gst_buffer_unref (priv);

  return TRUE;

}

static gboolean

gst_ssa_parse_remove_override_codes (GstSsaParse * parse, gchar * txt)

{

  gchar *t, *end;

  gboolean removed_any = FALSE;

  while ((t = strchr (txt, '{'))) {

    end = strchr (txt, '}');

    if (end == NULL) {

      GST_WARNING_OBJECT (parse, "Missing { for style override code");

      return removed_any;

    }

    /* move terminating NUL character forward as well */

    g_memmove (t, end + 1, strlen (end + 1) + 1);

    removed_any = TRUE;

  }

  /* these may occur outside of curly brackets. We don't handle the different

   * wrapping modes yet, so just remove these markers from the text for now */

  while ((t = strstr (txt, "\\n"))) {

    t[0] = ' ';

    t[1] = '\n';

  }

  while ((t = strstr (txt, "\\N"))) {

    t[0] = ' ';

    t[1] = '\n';

  }

  while ((t = strstr (txt, "\\h"))) {

    t[0] = ' ';

    t[1] = ' ';

  }

  return removed_any;

}

/**

 * gst_ssa_parse_push_line:

 * @parse: caller element

 * @txt: text to push

 * @start: timestamp for the buffer

 * @duration: duration for the buffer

 *

 * Parse the text in a buffer with the given properties and

 * push it to the srcpad of the @parse element

 *

 * Returns: result of the push of the created buffer

 */

static GstFlowReturn

gst_ssa_parse_push_line (GstSsaParse * parse, gchar * txt,

    GstClockTime start, GstClockTime duration)

{

  GstFlowReturn ret;

  GstBuffer *buf;

  gchar *t, *escaped;

  gint num, i, len;

  num = atoi (txt);

  GST_LOG_OBJECT (parse, "Parsing line #%d at %" GST_TIME_FORMAT,

      num, GST_TIME_ARGS (start));

  /* skip all non-text fields before the actual text */

  t = txt;

  for (i = 0; i < 8; ++i) {

    t = strchr (t, ',');

    if (t == NULL)

      return GST_FLOW_ERROR;

    ++t;

  }

  GST_LOG_OBJECT (parse, "Text : %s", t);

  if (gst_ssa_parse_remove_override_codes (parse, t)) {

    GST_LOG_OBJECT (parse, "Clean: %s", t);

  }

  /* we claim to output pango markup, so we must escape the

   * text even if we don't actually use any pango markup yet */

  escaped = g_markup_printf_escaped ("%s", t);

  len = strlen (escaped);

  /* allocate enough for a terminating NUL, but don't include it in buf size */

  buf = gst_buffer_new_and_alloc (len + 1);

  memcpy (GST_BUFFER_DATA (buf), escaped, len + 1);

  GST_BUFFER_SIZE (buf) = len;

  g_free (escaped);

  GST_BUFFER_TIMESTAMP (buf) = start;

  GST_BUFFER_DURATION (buf) = duration;

  gst_buffer_set_caps (buf, GST_PAD_CAPS (parse->srcpad));

  GST_LOG_OBJECT (parse, "Pushing buffer with timestamp %" GST_TIME_FORMAT

      " and duration %" GST_TIME_FORMAT, GST_TIME_ARGS (start),

      GST_TIME_ARGS (duration));

  ret = gst_pad_push (parse->srcpad, buf);

  if (ret != GST_FLOW_OK) {

    GST_DEBUG_OBJECT (parse, "Push of text '%s' returned flow %s", txt,

        gst_flow_get_name (ret));

  }

  return ret;

}

static GstFlowReturn

gst_ssa_parse_chain (GstPad * sinkpad, GstBuffer * buf)

{

  GstFlowReturn ret;

  GstSsaParse *parse = GST_SSA_PARSE (GST_PAD_PARENT (sinkpad));

  GstClockTime ts;

  gchar *txt;

  if (G_UNLIKELY (!parse->framed))

    goto not_framed;

  /* make double-sure it's 0-terminated and all */

  txt = g_strndup ((gchar *) GST_BUFFER_DATA (buf), GST_BUFFER_SIZE (buf));

  if (txt == NULL)

  ts = GST_BUFFER_TIMESTAMP (buf);

  ret = gst_ssa_parse_push_line (parse, txt, ts, GST_BUFFER_DURATION (buf));

  if (ret != GST_FLOW_OK && GST_CLOCK_TIME_IS_VALID (ts)) {

    /* just advance time without sending anything */

    gst_pad_push_event (parse->srcpad,

        gst_event_new_new_segment (TRUE, 1.0, GST_FORMAT_TIME, ts, -1, ts));

    ret = GST_FLOW_OK;

  }

  g_free (txt);

  return ret;

/* ERRORS */

not_framed:

  {

    GST_ELEMENT_ERROR (parse, STREAM, FORMAT, (NULL),

        ("Only SSA subtitles embedded in containers are supported"));

    return GST_FLOW_NOT_NEGOTIATED;

  }

}

static GstStateChangeReturn

gst_ssa_parse_change_state (GstElement * element, GstStateChange transition)

{

  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;

  GstSsaParse *parse = GST_SSA_PARSE (element);

  switch (transition) {

    case GST_STATE_CHANGE_READY_TO_PAUSED:

      break;

    default:

      break;

  }

  ret = parent_class->change_state (element, transition);

  if (ret == GST_STATE_CHANGE_FAILURE)

    return ret;

  switch (transition) {

    case GST_STATE_CHANGE_PAUSED_TO_READY:

      g_free (parse->ini);

      parse->ini = NULL;

      parse->framed = FALSE;

      break;

    default:

      break;

  }

  return ret;

}