/* GStreamer

 * Copyright (C) <2013> YouView TV Ltd.

 *

 * 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.

 */

/**

 * SECTION:gstprotection

 * @title: GstProtection

 * @short_description: Functions and classes to support encrypted streams.

 *

 * The GstProtectionMeta class enables the information needed to decrypt a

 * #GstBuffer to be attached to that buffer.

 *

 * Typically, a demuxer element would attach GstProtectionMeta objects

 * to the buffers that it pushes downstream. The demuxer would parse the

 * protection information for a video/audio frame from its input data and use

 * this information to populate the #GstStructure @info field,

 * which is then encapsulated in a GstProtectionMeta object and attached to

 * the corresponding output buffer using the gst_buffer_add_protection_meta()

 * function. The information in this attached GstProtectionMeta would be

 * used by a downstream decrypter element to recover the original unencrypted

 * frame.

 *

 * Since: 1.6

 */

#include "gst_private.h"

#include "glib-compat-private.h"

#include "gstprotection.h"

#define GST_CAT_DEFAULT GST_CAT_PROTECTION

static gboolean gst_protection_meta_init (GstMeta * meta, gpointer params,

    GstBuffer * buffer);

static void gst_protection_meta_free (GstMeta * meta, GstBuffer * buffer);

static const gchar *gst_protection_factory_check (GstElementFactory * fact,

    const gchar ** system_identifiers);

GType

gst_protection_meta_api_get_type (void)

{

  static volatile GType type;

  static const gchar *tags[] = { NULL };

  if (g_once_init_enter (&type)) {

    GType _type = gst_meta_api_type_register ("GstProtectionMetaAPI", tags);

    g_once_init_leave (&type, _type);

  }

  return type;

}

static gboolean

gst_protection_meta_init (GstMeta * meta, gpointer params, GstBuffer * buffer)

{

  GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;

  protection_meta->info = NULL;

  return TRUE;

}

static void

gst_protection_meta_free (GstMeta * meta, GstBuffer * buffer)

{

  GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;

  if (protection_meta->info)

    gst_structure_free (protection_meta->info);

}

static gboolean

gst_protection_meta_transform (GstBuffer * transbuf, GstMeta * meta,

    GstBuffer * buffer, GQuark type, gpointer data)

{

  GstProtectionMeta *protection_meta = (GstProtectionMeta *) meta;

  if (GST_META_TRANSFORM_IS_COPY (type)) {

    GstMetaTransformCopy *copy = data;

    if (!copy->region) {

      /* only copy if the complete data is copied as well */

      gst_buffer_add_protection_meta (transbuf,

          gst_structure_copy (protection_meta->info));

    } else {

      return FALSE;

    }

  } else {

    /* transform type not supported */

    return FALSE;

  }

  return TRUE;

}

const GstMetaInfo *

gst_protection_meta_get_info (void)

{

  static const GstMetaInfo *protection_meta_info = NULL;

  if (g_once_init_enter ((GstMetaInfo **) & protection_meta_info)) {

    const GstMetaInfo *meta =

        gst_meta_register (GST_PROTECTION_META_API_TYPE, "GstProtectionMeta",

        sizeof (GstProtectionMeta), gst_protection_meta_init,

        gst_protection_meta_free, gst_protection_meta_transform);

    g_once_init_leave ((GstMetaInfo **) & protection_meta_info,

        (GstMetaInfo *) meta);

  }

  return protection_meta_info;

}

/**

 * gst_buffer_add_protection_meta:

 * @buffer: #GstBuffer holding an encrypted sample, to which protection

 *     metadata should be added.

 * @info: (transfer full): a #GstStructure holding cryptographic

 *     information relating to the sample contained in @buffer. This

 *     function takes ownership of @info.

 *

 * Attaches protection metadata to a #GstBuffer.

 *

 * Returns: (transfer none): a pointer to the added #GstProtectionMeta if successful; %NULL if

 * unsuccessful.

 *

 * Since: 1.6

 */

GstProtectionMeta *

gst_buffer_add_protection_meta (GstBuffer * buffer, GstStructure * info)

{

  GstProtectionMeta *meta;

  g_return_val_if_fail (GST_IS_BUFFER (buffer), NULL);

  g_return_val_if_fail (info != NULL, NULL);

  meta =

      (GstProtectionMeta *) gst_buffer_add_meta (buffer,

      GST_PROTECTION_META_INFO, NULL);

  meta->info = info;

  return meta;

}

/**

 * gst_protection_select_system:

 * @system_identifiers: (transfer none) (array zero-terminated=1): A null terminated array of strings

 * that contains the UUID values of each protection system that is to be

 * checked.

 *

 * Iterates the supplied list of UUIDs and checks the GstRegistry for

 * an element that supports one of the supplied UUIDs. If more than one

 * element matches, the system ID of the highest ranked element is selected.

 *

 * Returns: (transfer none) (nullable): One of the strings from

 * @system_identifiers that indicates the highest ranked element that

 * implements the protection system indicated by that system ID, or %NULL if no

 * element has been found.

 *

 * Since: 1.6

 */

const gchar *

gst_protection_select_system (const gchar ** system_identifiers)

{

  GList *decryptors, *walk;

  const gchar *retval = NULL;

  decryptors =

      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECRYPTOR,

      GST_RANK_MARGINAL);

  for (walk = decryptors; !retval && walk; walk = g_list_next (walk)) {

    GstElementFactory *fact = (GstElementFactory *) walk->data;

    retval = gst_protection_factory_check (fact, system_identifiers);

  }

  gst_plugin_feature_list_free (decryptors);

  return retval;

}

/**

 * gst_protection_filter_systems_by_available_decryptors:

 * @system_identifiers: (transfer none): A null terminated array of strings

 * that contains the UUID values of each protection system that is to be

 * checked.

 *

 * Iterates the supplied list of UUIDs and checks the GstRegistry for

 * all the decryptors supporting one of the supplied UUIDs.

 *

 * Returns: (transfer full) (nullable): A null terminated array containing all

 * the @system_identifiers supported by the set of available decryptors, or

 * %NULL if no matches were found.

 *

 * Since: 1.14

 */

gchar **

gst_protection_filter_systems_by_available_decryptors (const gchar **

    system_identifiers)

{

  GList *decryptors, *walk;

  gchar **retval;

  guint i = 0, decryptors_number;

  decryptors =

      gst_element_factory_list_get_elements (GST_ELEMENT_FACTORY_TYPE_DECRYPTOR,

      GST_RANK_MARGINAL);

  decryptors_number = g_list_length (decryptors);

  GST_TRACE ("found %u decrytors", decryptors_number);

  if (decryptors_number == 0)

    return NULL;

  retval = g_new (gchar *, decryptors_number + 1);

  for (walk = decryptors; walk; walk = g_list_next (walk)) {

    GstElementFactory *fact = (GstElementFactory *) walk->data;

    const char *found_sys_id =

        gst_protection_factory_check (fact, system_identifiers);

    GST_DEBUG ("factory %s is valid for %s", GST_OBJECT_NAME (fact),

        found_sys_id);

    if (found_sys_id) {

      retval[i++] = g_strdup (found_sys_id);

    }

  }

  retval[i] = NULL;

  if (retval[0] == NULL) {

    g_free (retval);

    retval = NULL;

  }

  gst_plugin_feature_list_free (decryptors);

  return retval;

}

static const gchar *

gst_protection_factory_check (GstElementFactory * fact,

    const gchar ** system_identifiers)

{

  const GList *template, *walk;

  const gchar *retval = NULL;

  template = gst_element_factory_get_static_pad_templates (fact);

  for (walk = template; walk && !retval; walk = g_list_next (walk)) {

    GstStaticPadTemplate *templ = walk->data;

    GstCaps *caps = gst_static_pad_template_get_caps (templ);

    guint leng = gst_caps_get_size (caps);

    guint i, j;

    for (i = 0; !retval && i < leng; ++i) {

      GstStructure *st;

      st = gst_caps_get_structure (caps, i);

      if (gst_structure_has_field_typed (st,

              GST_PROTECTION_SYSTEM_ID_CAPS_FIELD, G_TYPE_STRING)) {

        const gchar *sys_id =

            gst_structure_get_string (st, GST_PROTECTION_SYSTEM_ID_CAPS_FIELD);

        GST_DEBUG ("Found decryptor that supports protection system %s",

            sys_id);

        for (j = 0; !retval && system_identifiers[j]; ++j) {

          GST_TRACE ("  compare with %s", system_identifiers[j]);

          if (g_ascii_strcasecmp (system_identifiers[j], sys_id) == 0) {

            GST_DEBUG ("  Selecting %s", system_identifiers[j]);

            retval = system_identifiers[j];

          }

        }

      }

    }

    gst_caps_unref (caps);

  }

  return retval;

}