/* GStreamer

 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

 * Copyright (C) 2000,2005 Wim Taymans <wim@fluendo.com>

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

 *

 * gsttypefindhelper.c:

 *

 * 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.

 */

/**

 * SECTION:gsttypefindhelper

 * @short_description: Utility functions for typefinding 

 *

 * Utility functions for elements doing typefinding:

 * gst_type_find_helper() does typefinding in pull mode, while

 * gst_type_find_helper_for_buffer() is useful for elements needing to do

 * typefinding in push mode from a chain function.

 */

#ifdef HAVE_CONFIG_H

#  include "config.h"

#endif

#include <stdlib.h>

#include <string.h>

#include "gsttypefindhelper.h"

static gint

type_find_factory_rank_cmp (gconstpointer fac1, gconstpointer fac2)

{

  if (GST_PLUGIN_FEATURE (fac1)->rank != GST_PLUGIN_FEATURE (fac2)->rank)

    return GST_PLUGIN_FEATURE (fac2)->rank - GST_PLUGIN_FEATURE (fac1)->rank;

  /* to make the order in which things happen more deterministic,

   * sort by name when the ranks are the same. */

  return strcmp (GST_PLUGIN_FEATURE_NAME (fac1),

      GST_PLUGIN_FEATURE_NAME (fac2));

}

/* ********************** typefinding in pull mode ************************ */

typedef struct

{

  GSList *buffers;              /* buffer cache */

  guint64 size;

  guint64 last_offset;

  GstTypeFindHelperGetRangeFunction func;

  guint best_probability;

  GstCaps *caps;

  GstTypeFindFactory *factory;  /* for logging */

  GstObject *obj;               /* for logging */

} GstTypeFindHelper;

/*

 * helper_find_peek:

 * @data: helper data struct

 * @off: stream offset

 * @size: block size

 *

 * Get data pointer within a stream. Keeps a cache of read buffers (partly

 * for performance reasons, but mostly because pointers returned by us need

 * to stay valid until typefinding has finished)

 *

 * Returns: address of the data or %NULL if buffer does not cover the

 * requested range.

 */

static guint8 *

helper_find_peek (gpointer data, gint64 offset, guint size)

{

  GstTypeFindHelper *helper;

  GstBuffer *buffer;

  GstFlowReturn ret;

  GSList *insert_pos = NULL;

  helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT

      ", %u)", GST_PLUGIN_FEATURE_NAME (helper->factory), offset, size);

  if (size == 0)

    return NULL;

  if (offset < 0) {

    if (helper->size == -1 || helper->size < -offset)

      return NULL;

    offset += helper->size;

  }

  /* see if we have a matching buffer already in our list */

  if (size > 0 && offset <= helper->last_offset) {

    GSList *walk;

    for (walk = helper->buffers; walk; walk = walk->next) {

      GstBuffer *buf = GST_BUFFER_CAST (walk->data);

      guint64 buf_offset = GST_BUFFER_OFFSET (buf);

      guint buf_size = GST_BUFFER_SIZE (buf);

      if (buf_offset <= offset) {

        if ((offset + size) < (buf_offset + buf_size)) {

          return GST_BUFFER_DATA (buf) + (offset - buf_offset);

        }

        insert_pos = walk;

        break;

      }

    }

  }

  buffer = NULL;

  /* some typefinders go in 1 byte steps over 1k of data and request

   * small buffers. It is really inefficient to pull each time, and pulling

   * a larger chunk is almost free. Trying to pull a larger chunk at the end

   * of the file is also not a problem here, we'll just get a truncated buffer

   * in that case (and we'll have to double-check the size we actually get

   * anyway, see below) */

  if (ret != GST_FLOW_OK)

    goto error;

  /* getrange might silently return shortened buffers at the end of a file,

   * we must, however, always return either the full requested data or NULL */

    GST_DEBUG ("droping short buffer: %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT

        " instead of %" G_GUINT64_FORMAT "-%" G_GUINT64_FORMAT,

    gst_buffer_unref (buffer);

    return NULL;

  }

  if (insert_pos) {

    helper->buffers =

        g_slist_insert_before (helper->buffers, insert_pos, buffer);

  } else {

    /* if insert_pos is not set, our offset is bigger than the largest offset

     * we have so far; since we keep the list sorted with highest offsets

     * first, we need to prepend the buffer to the list */

    helper->buffers = g_slist_prepend (helper->buffers, buffer);

  }

  return GST_BUFFER_DATA (buffer);

error:

  {

    GST_INFO ("typefind function returned: %s", gst_flow_get_name (ret));

    return NULL;

  }

}

/*

 * helper_find_suggest:

 * @data: helper data struct

 * @probability: probability of the match

 * @caps: caps of the type

 *

 * If given @probability is higher, replace previously store caps.

 */

static void

helper_find_suggest (gpointer data, guint probability, const GstCaps * caps)

{

  GstTypeFindHelper *helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj,

      "'%s' called called suggest (%u, %" GST_PTR_FORMAT ")",

      GST_PLUGIN_FEATURE_NAME (helper->factory), probability, caps);

  if (probability > helper->best_probability) {

    GstCaps *copy = gst_caps_copy (caps);

    gst_caps_replace (&helper->caps, copy);

    gst_caps_unref (copy);

    helper->best_probability = probability;

  }

}

static guint64

helper_find_get_length (gpointer data)

{

  GstTypeFindHelper *helper = (GstTypeFindHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called called get_length, returning %"

      G_GUINT64_FORMAT, GST_PLUGIN_FEATURE_NAME (helper->factory),

      helper->size);

  return helper->size;

}

/**

 * gst_type_find_helper_get_range:

 * @obj: A #GstObject that will be passed as first argument to @func

 * @func: A generic #GstTypeFindHelperGetRangeFunction that will be used

 *        to access data at random offsets when doing the typefinding

 * @size: The length in bytes

 * @prob: location to store the probability of the found caps, or #NULL

 *

 * Utility function to do pull-based typefinding. Unlike gst_type_find_helper()

 * however, this function will use the specified function @func to obtain the

 * data needed by the typefind functions, rather than operating on a given

 * source pad. This is useful mostly for elements like tag demuxers which

 * strip off data at the beginning and/or end of a file and want to typefind

 * the stripped data stream before adding their own source pad (the specified

 * callback can then call the upstream peer pad with offsets adjusted for the

 * tag size, for example).

 *

 * Returns: The #GstCaps corresponding to the data stream.

 * Returns #NULL if no #GstCaps matches the data stream.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstCaps *

gst_type_find_helper_get_range (GstObject * obj,

    GstTypeFindHelperGetRangeFunction func, guint64 size,

    GstTypeFindProbability * prob)

{

  GstTypeFindHelper helper;

  GstTypeFind find;

  GSList *walk;

  GList *l, *type_list;

  GstCaps *result = NULL;

  g_return_val_if_fail (GST_IS_OBJECT (obj), NULL);

  g_return_val_if_fail (func != NULL, NULL);

  helper.buffers = NULL;

  helper.size = size;

  helper.last_offset = 0;

  helper.func = func;

  helper.best_probability = 0;

  helper.caps = NULL;

  helper.obj = obj;

  find.data = &helper;

  find.peek = helper_find_peek;

  find.suggest = helper_find_suggest;

  if (size == 0 || size == (guint64) - 1) {

    find.get_length = NULL;

  } else {

    find.get_length = helper_find_get_length;

  }

  /* FIXME: we need to keep this list within the registry */

  type_list = gst_type_find_factory_get_list ();

  type_list = g_list_sort (type_list, type_find_factory_rank_cmp);

  for (l = type_list; l; l = l->next) {

    helper.factory = GST_TYPE_FIND_FACTORY (l->data);

    gst_type_find_factory_call_function (helper.factory, &find);

    if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)

      break;

  }

  gst_plugin_feature_list_free (type_list);

  for (walk = helper.buffers; walk; walk = walk->next)

    gst_buffer_unref (GST_BUFFER_CAST (walk->data));

  g_slist_free (helper.buffers);

  if (helper.best_probability > 0)

    result = helper.caps;

  if (prob)

    *prob = helper.best_probability;

  GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",

      result, (guint) helper.best_probability);

  return result;

}

/**

 * gst_type_find_helper:

 * @src: A source #GstPad

 * @size: The length in bytes

 *

 * Tries to find what type of data is flowing from the given source #GstPad.

 *

 * Returns: The #GstCaps corresponding to the data stream.

 * Returns #NULL if no #GstCaps matches the data stream.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstCaps *

gst_type_find_helper (GstPad * src, guint64 size)

{

  GstTypeFindHelperGetRangeFunction func;

  g_return_val_if_fail (GST_IS_OBJECT (src), NULL);

  g_return_val_if_fail (GST_PAD_GETRANGEFUNC (src) != NULL, NULL);

  func = (GstTypeFindHelperGetRangeFunction) (GST_PAD_GETRANGEFUNC (src));

  return gst_type_find_helper_get_range (GST_OBJECT (src), func, size, NULL);

}

/* ********************** typefinding for buffers ************************* */

typedef struct

{

  guint8 *data;                 /* buffer data */

  guint size;

  guint best_probability;

  GstCaps *caps;

  GstTypeFindFactory *factory;  /* for logging */

  GstObject *obj;               /* for logging */

} GstTypeFindBufHelper;

/*

 * buf_helper_find_peek:

 * @data: helper data struct

 * @off: stream offset

 * @size: block size

 *

 * Get data pointer within a buffer.

 *

 * Returns: address inside the buffer or %NULL if buffer does not cover the

 * requested range.

 */

static guint8 *

buf_helper_find_peek (gpointer data, gint64 off, guint size)

{

  GstTypeFindBufHelper *helper;

  helper = (GstTypeFindBufHelper *) data;

  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)",

      GST_PLUGIN_FEATURE_NAME (helper->factory), off, size);

  if (size == 0)

    return NULL;

  if (off < 0) {

    GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported",

        GST_PLUGIN_FEATURE_NAME (helper->factory));

    return NULL;

  }

  if ((off + size) <= helper->size)

    return helper->data + off;

  return NULL;

}

/*

 * buf_helper_find_suggest:

 * @data: helper data struct

 * @probability: probability of the match

 * @caps: caps of the type

 *

 * If given @probability is higher, replace previously store caps.

 */

static void

buf_helper_find_suggest (gpointer data, guint probability, const GstCaps * caps)

{

  GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;

  GST_LOG_OBJECT (helper->obj,

      "'%s' called called suggest (%u, %" GST_PTR_FORMAT ")",

      GST_PLUGIN_FEATURE_NAME (helper->factory), probability, caps);

  /* Note: not >= as we call typefinders in order of rank, highest first */

  if (probability > helper->best_probability) {

    GstCaps *copy = gst_caps_copy (caps);

    gst_caps_replace (&helper->caps, copy);

    gst_caps_unref (copy);

    helper->best_probability = probability;

  }

}

/**

 * gst_type_find_helper_for_buffer:

 * @obj: object doing the typefinding, or NULL (used for logging)

 * @buf: a #GstBuffer with data to typefind

 * @prob: location to store the probability of the found caps, or #NULL

 *

 * Tries to find what type of data is contained in the given #GstBuffer, the

 * assumption being that the buffer represents the beginning of the stream or

 * file.

 *

 * All available typefinders will be called on the data in order of rank. If

 * a typefinding function returns a probability of #GST_TYPE_FIND_MAXIMUM,

 * typefinding is stopped immediately and the found caps will be returned

 * right away. Otherwise, all available typefind functions will the tried,

 * and the caps with the highest probability will be returned, or #NULL if

 * the content of the buffer could not be identified.

 *

 * Returns: The #GstCaps corresponding to the data, or #NULL if no type could

 * be found. The caller should free the caps returned with gst_caps_unref().

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstCaps *

gst_type_find_helper_for_buffer (GstObject * obj, GstBuffer * buf,

    GstTypeFindProbability * prob)

{

  GstTypeFindBufHelper helper;

  GstTypeFind find;

  GList *l, *type_list;

  GstCaps *result = NULL;

  g_return_val_if_fail (buf != NULL, NULL);

  g_return_val_if_fail (GST_IS_BUFFER (buf), NULL);

  g_return_val_if_fail (GST_BUFFER_OFFSET (buf) == 0 ||

      GST_BUFFER_OFFSET (buf) == GST_BUFFER_OFFSET_NONE, NULL);

  helper.data = GST_BUFFER_DATA (buf);

  helper.size = GST_BUFFER_SIZE (buf);

  helper.best_probability = 0;

  helper.caps = NULL;

  helper.obj = obj;

  if (helper.data == NULL || helper.size == 0)

    return NULL;

  find.data = &helper;

  find.peek = buf_helper_find_peek;

  find.suggest = buf_helper_find_suggest;

  find.get_length = NULL;

  /* FIXME: we need to keep this list within the registry */

  type_list = gst_type_find_factory_get_list ();

  type_list = g_list_sort (type_list, type_find_factory_rank_cmp);

  for (l = type_list; l; l = l->next) {

    helper.factory = GST_TYPE_FIND_FACTORY (l->data);

    gst_type_find_factory_call_function (helper.factory, &find);

    if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)

      break;

  }

  gst_plugin_feature_list_free (type_list);

  if (helper.best_probability > 0)

    result = helper.caps;

  if (prob)

    *prob = helper.best_probability;

  GST_LOG_OBJECT (obj, "Returning %" GST_PTR_FORMAT " (probability = %u)",

      result, (guint) helper.best_probability);

  return result;

}