/* GStreamer

 * Copyright (C) 2005 Stefan Kost <ensonic@users.sf.net>

 *

 * gstchildproxy.c: interface for multi child elements

 *

 * 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:gstchildproxy

 * @title: GstChildProxy

 * @short_description: Interface for multi child elements.

 * @see_also: #GstBin

 *

 * This interface abstracts handling of property sets for elements with

 * children. Imagine elements such as mixers or polyphonic generators. They all

 * have multiple #GstPad or some kind of voice objects. Another use case are

 * container elements like #GstBin.

 * The element implementing the interface acts as a parent for those child

 * objects.

 *

 * By implementing this interface the child properties can be accessed from the

 * parent element by using gst_child_proxy_get() and gst_child_proxy_set().

 *

 * Property names are written as "child-name::property-name". The whole naming

 * scheme is recursive. Thus "child1::child2::property" is valid too, if

 * "child1" and "child2" implement the #GstChildProxy interface.

 */

#include "gst_private.h"

#include "gstchildproxy.h"

#include <gobject/gvaluecollector.h>

/* signals */

enum

{

  CHILD_ADDED,

  CHILD_REMOVED,

  LAST_SIGNAL

};

static guint signals[LAST_SIGNAL] = { 0 };

static GObject *

gst_child_proxy_default_get_child_by_name (GstChildProxy * parent,

    const gchar * name)

{

  guint count, i;

  GObject *object, *result;

  gchar *object_name;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);

  g_return_val_if_fail (name != NULL, NULL);

  result = NULL;

  count = gst_child_proxy_get_children_count (parent);

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

    gboolean eq;

    if (!(object = gst_child_proxy_get_child_by_index (parent, i)))

      continue;

    if (!GST_IS_OBJECT (object)) {

      goto next;

    }

    object_name = gst_object_get_name (GST_OBJECT_CAST (object));

    if (object_name == NULL) {

      g_warning ("child %u of parent %s has no name", i,

          GST_OBJECT_NAME (parent));

      goto next;

    }

    eq = g_str_equal (object_name, name);

    g_free (object_name);

    if (eq) {

      result = object;

      break;

    }

  next:

    g_object_unref (object);

  }

  return result;

}

/**

 * gst_child_proxy_get_child_by_name:

 * @parent: the parent object to get the child from

 * @name: the child's name

 *

 * Looks up a child element by the given name.

 *

 * This virtual method has a default implementation that uses #GstObject

 * together with gst_object_get_name(). If the interface is to be used with

 * #GObjects, this methods needs to be overridden.

 *

 * Returns: (transfer full) (nullable): the child object or %NULL if

 *     not found. Unref after usage.

 *

 * MT safe.

 */

GObject *

gst_child_proxy_get_child_by_name (GstChildProxy * parent, const gchar * name)

{

  GstChildProxyInterface *iface;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);

  iface = GST_CHILD_PROXY_GET_INTERFACE (parent);

  if (iface->get_child_by_name != NULL)

    return iface->get_child_by_name (parent, name);

  return NULL;

}

/**

 * gst_child_proxy_get_child_by_index:

 * @parent: the parent object to get the child from

 * @index: the child's position in the child list

 *

 * Fetches a child by its number.

 *

 * Returns: (transfer full) (nullable): the child object or %NULL if

 *     not found (index too high). Unref after usage.

 *

 * MT safe.

 */

GObject *

gst_child_proxy_get_child_by_index (GstChildProxy * parent, guint index)

{

  GstChildProxyInterface *iface;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);

  iface = GST_CHILD_PROXY_GET_INTERFACE (parent);

  if (iface->get_child_by_index != NULL)

    return iface->get_child_by_index (parent, index);

  return NULL;

}

/**

 * gst_child_proxy_get_children_count:

 * @parent: the parent object

 *

 * Gets the number of child objects this parent contains.

 *

 * Returns: the number of child objects

 *

 * MT safe.

 */

guint

gst_child_proxy_get_children_count (GstChildProxy * parent)

{

  GstChildProxyInterface *iface;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);

  iface = GST_CHILD_PROXY_GET_INTERFACE (parent);

  if (iface->get_children_count != NULL)

    return iface->get_children_count (parent);

  return 0;

}

/**

 * gst_child_proxy_lookup:

 * @object: child proxy object to lookup the property in

 * @name: name of the property to look up

 * @target: (out) (allow-none) (transfer full): pointer to a #GObject that

 *     takes the real object to set property on

 * @pspec: (out) (allow-none) (transfer none): pointer to take the #GParamSpec

 *     describing the property

 *

 * Looks up which object and #GParamSpec would be effected by the given @name.

 *

 * MT safe.

 *

 * Returns: %TRUE if @target and @pspec could be found. %FALSE otherwise. In that

 * case the values for @pspec and @target are not modified. Unref @target after

 * usage. For plain GObjects @target is the same as @object.

 */

gboolean

gst_child_proxy_lookup (GstChildProxy * object, const gchar * name,

    GObject ** target, GParamSpec ** pspec)

{

  GObject *obj;

  gboolean res = FALSE;

  gchar **names, **current;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (object), FALSE);

  g_return_val_if_fail (name != NULL, FALSE);

  obj = G_OBJECT (g_object_ref (object));

  current = names = g_strsplit (name, "::", -1);

  /* find the owner of the property */

  while (current[1]) {

    GObject *next;

    if (!GST_IS_CHILD_PROXY (obj)) {

      GST_INFO

          ("object %s is not a parent, so you cannot request a child by name %s",

          (GST_IS_OBJECT (obj) ? GST_OBJECT_NAME (obj) : ""), current[0]);

      break;

    }

    next = gst_child_proxy_get_child_by_name (GST_CHILD_PROXY (obj),

        current[0]);

    if (!next) {

      GST_INFO ("no such object %s", current[0]);

      break;

    }

    g_object_unref (obj);

    obj = next;

    current++;

  }

  /* look for psec */

  if (current[1] == NULL) {

    GParamSpec *spec =

        g_object_class_find_property (G_OBJECT_GET_CLASS (obj), current[0]);

    if (spec == NULL) {

      GST_INFO ("no param spec named %s", current[0]);

    } else {

      if (pspec)

        *pspec = spec;

      if (target) {

        g_object_ref (obj);

        *target = obj;

      }

      res = TRUE;

    }

  }

  g_object_unref (obj);

  g_strfreev (names);

  return res;

}

/**

 * gst_child_proxy_get_property:

 * @object: object to query

 * @name: name of the property

 * @value: (out caller-allocates): a #GValue that should take the result.

 *

 * Gets a single property using the GstChildProxy mechanism.

 * You are responsible for freeing it by calling g_value_unset()

 */

void

gst_child_proxy_get_property (GstChildProxy * object, const gchar * name,

    GValue * value)

{

  GParamSpec *pspec;

  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  g_return_if_fail (name != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  if (!gst_child_proxy_lookup (object, name, &target, &pspec))

    goto not_found;

  g_object_get_property (target, pspec->name, value);

  g_object_unref (target);

  return;

not_found:

  {

    g_warning ("no property %s in object %s", name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));

    return;

  }

}

/**

 * gst_child_proxy_get_valist:

 * @object: the object to query

 * @first_property_name: name of the first property to get

 * @var_args: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL

 *

 * Gets properties of the parent object and its children.

 */

void

gst_child_proxy_get_valist (GstChildProxy * object,

    const gchar * first_property_name, va_list var_args)

{

  const gchar *name;

  gchar *error = NULL;

  GValue value = { 0, };

  GParamSpec *pspec;

  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  name = first_property_name;

  /* iterate over pairs */

  while (name) {

    if (!gst_child_proxy_lookup (object, name, &target, &pspec))

      goto not_found;

    g_value_init (&value, pspec->value_type);

    g_object_get_property (target, pspec->name, &value);

    g_object_unref (target);

    G_VALUE_LCOPY (&value, var_args, 0, &error);

    if (error)

      goto cant_copy;

    g_value_unset (&value);

    name = va_arg (var_args, gchar *);

  }

  return;

not_found:

  {

    g_warning ("no property %s in object %s", name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));

    return;

  }

cant_copy:

  {

    g_warning ("error copying value %s in object %s: %s", pspec->name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);

    g_value_unset (&value);

    return;

  }

}

/**

 * gst_child_proxy_get:

 * @object: the parent object

 * @first_property_name: name of the first property to get

 * @...: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL

 *

 * Gets properties of the parent object and its children.

 */

void

gst_child_proxy_get (GstChildProxy * object, const gchar * first_property_name,

    ...)

{

  va_list var_args;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  va_start (var_args, first_property_name);

  gst_child_proxy_get_valist (object, first_property_name, var_args);

  va_end (var_args);

}

/**

 * gst_child_proxy_set_property:

 * @object: the parent object

 * @name: name of the property to set

 * @value: new #GValue for the property

 *

 * Sets a single property using the GstChildProxy mechanism.

 */

void

gst_child_proxy_set_property (GstChildProxy * object, const gchar * name,

    const GValue * value)

{

  GParamSpec *pspec;

  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  g_return_if_fail (name != NULL);

  g_return_if_fail (G_IS_VALUE (value));

  if (!gst_child_proxy_lookup (object, name, &target, &pspec))

    goto not_found;

  g_object_set_property (target, pspec->name, value);

  g_object_unref (target);

  return;

not_found:

  {

    g_warning ("cannot set property %s on object %s", name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));

    return;

  }

}

/**

 * gst_child_proxy_set_valist:

 * @object: the parent object

 * @first_property_name: name of the first property to set

 * @var_args: value for the first property, followed optionally by more name/value pairs, followed by %NULL

 *

 * Sets properties of the parent object and its children.

 */

void

gst_child_proxy_set_valist (GstChildProxy * object,

    const gchar * first_property_name, va_list var_args)

{

  const gchar *name;

  gchar *error = NULL;

  GValue value = { 0, };

  GParamSpec *pspec;

  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  name = first_property_name;

  /* iterate over pairs */

  while (name) {

    if (!gst_child_proxy_lookup (object, name, &target, &pspec))

      goto not_found;

    G_VALUE_COLLECT_INIT (&value, pspec->value_type, var_args,

        G_VALUE_NOCOPY_CONTENTS, &error);

    if (error)

      goto cant_copy;

    g_object_set_property (target, pspec->name, &value);

    g_object_unref (target);

    g_value_unset (&value);

    name = va_arg (var_args, gchar *);

  }

  return;

not_found:

  {

    g_warning ("no property %s in object %s", name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));

    return;

  }

cant_copy:

  {

    g_warning ("error copying value %s in object %s: %s", pspec->name,

        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);

    g_value_unset (&value);

    g_object_unref (target);

    return;

  }

}

/**

 * gst_child_proxy_set:

 * @object: the parent object

 * @first_property_name: name of the first property to set

 * @...: value for the first property, followed optionally by more name/value pairs, followed by %NULL

 *

 * Sets properties of the parent object and its children.

 */

void

gst_child_proxy_set (GstChildProxy * object, const gchar * first_property_name,

    ...)

{

  va_list var_args;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  va_start (var_args, first_property_name);

  gst_child_proxy_set_valist (object, first_property_name, var_args);

  va_end (var_args);

}

/**

 * gst_child_proxy_child_added:

 * @parent: the parent object

 * @child: the newly added child

 * @name: the name of the new child

 *

 * Emits the "child-added" signal.

 */

void

gst_child_proxy_child_added (GstChildProxy * parent, GObject * child,

    const gchar * name)

{

  g_signal_emit (parent, signals[CHILD_ADDED], 0, child, name);

}

/**

 * gst_child_proxy_child_removed:

 * @parent: the parent object

 * @child: the removed child

 * @name: the name of the old child

 *

 * Emits the "child-removed" signal.

 */

void

gst_child_proxy_child_removed (GstChildProxy * parent, GObject * child,

    const gchar * name)

{

  g_signal_emit (parent, signals[CHILD_REMOVED], 0, child, name);

}

/* gobject methods */

static void

gst_child_proxy_class_init (gpointer g_class, gpointer class_data)

{

  GstChildProxyInterface *iface = (GstChildProxyInterface *) g_class;

  iface->get_child_by_name = gst_child_proxy_default_get_child_by_name;

}

static void

gst_child_proxy_base_init (gpointer g_class)

{

  static gboolean initialized = FALSE;

  if (!initialized) {

    /* create interface signals and properties here. */

    /**

     * GstChildProxy::child-added:

     * @child_proxy: the #GstChildProxy

     * @object: the #GObject that was added

     * @name: the name of the new child

     *

     * Will be emitted after the @object was added to the @child_proxy.

     */

    signals[CHILD_ADDED] =

        g_signal_new ("child-added", G_TYPE_FROM_CLASS (g_class),

        G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,

            child_added), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,

        2, G_TYPE_OBJECT, G_TYPE_STRING);

    /**

     * GstChildProxy::child-removed:

     * @child_proxy: the #GstChildProxy

     * @object: the #GObject that was removed

     * @name: the name of the old child

     *

     * Will be emitted after the @object was removed from the @child_proxy.

     */

    signals[CHILD_REMOVED] =

        g_signal_new ("child-removed", G_TYPE_FROM_CLASS (g_class),

        G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,

            child_removed), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,

        2, G_TYPE_OBJECT, G_TYPE_STRING);

    initialized = TRUE;

  }

}

GType

gst_child_proxy_get_type (void)

{

  static volatile gsize type = 0;

  if (g_once_init_enter (&type)) {

    GType _type;

    static const GTypeInfo info = {

      sizeof (GstChildProxyInterface),

      gst_child_proxy_base_init,        /* base_init */

      NULL,                     /* base_finalize */

      gst_child_proxy_class_init,       /* class_init */

      NULL,                     /* class_finalize */

      NULL,                     /* class_data */

      0,

      0,                        /* n_preallocs */

      NULL                      /* instance_init */

    };

    _type =

        g_type_register_static (G_TYPE_INTERFACE, "GstChildProxy", &info, 0);

    g_type_interface_add_prerequisite (_type, G_TYPE_OBJECT);

    g_once_init_leave (&type, (gsize) _type);

  }

  return type;

}