/* GStreamer

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

 *                    2000 Wim Taymans <wtay@chello.be>

 *

 * gstxml.c: XML save/restore of pipelines

 *

 * 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:gstxml

 * @short_description: XML save/restore operations of pipelines

 *

 * GStreamer pipelines can be saved to xml files using gst_xml_write_file().

 * They can be loaded back using gst_xml_parse_doc() / gst_xml_parse_file() / 

 * gst_xml_parse_memory().

 * Additionally one can load saved pipelines into the gst-editor to inspect the

 * graph.

 *

 */

#include "gst_private.h"

#include "gstxml.h"

#include "gstmarshal.h"

#include "gstinfo.h"

#include "gstbin.h"

enum

{

  OBJECT_LOADED,

  LAST_SIGNAL

};

static void gst_xml_class_init (GstXMLClass * klass);

static void gst_xml_init (GstXML * xml);

static void gst_xml_dispose (GObject * object);

static void gst_xml_object_loaded (GstObject * private, GstObject * object,

    xmlNodePtr self, gpointer data);

static GstObjectClass *parent_class = NULL;

static guint gst_xml_signals[LAST_SIGNAL] = { 0 };

static void

gst_xml_class_init (GstXMLClass * klass)

{

  parent_class = g_type_class_peek_parent (klass);

  gobject_class->dispose = GST_DEBUG_FUNCPTR (gst_xml_dispose);

  /* FIXME G_TYPE_POINTER should be GType of xmlNodePtr

   * (ensonic) can't be fixed, as libxml does not use GObject (unfortunately)

   */

  /**

   * GstXML::object-loaded:

   * @xml: the xml persistence instance

   * @object: the object that has been loaded

   * @xml_node: the related xml_node pointer to the document tree

   *

   * Signals that a new object has been deserialized.

   */

  gst_xml_signals[OBJECT_LOADED] =

      g_signal_new ("object-loaded", G_TYPE_FROM_CLASS (klass),

      G_SIGNAL_RUN_LAST, G_STRUCT_OFFSET (GstXMLClass, object_loaded), NULL,

      NULL, gst_marshal_VOID__OBJECT_POINTER, G_TYPE_NONE, 2, GST_TYPE_OBJECT,

      G_TYPE_POINTER);

}

static void

gst_xml_init (GstXML * xml)

{

  xml->topelements = NULL;

}

static void

gst_xml_dispose (GObject * object)

{

  GstXML *xml = GST_XML (object);

  g_list_foreach (xml->topelements, (GFunc) gst_object_unref, NULL);

  g_list_free (xml->topelements);

  xml->topelements = NULL;

  G_OBJECT_CLASS (parent_class)->dispose (object);

}

/**

 * gst_xml_new:

 *

 * Create a new GstXML parser object.

 *

 * Returns: a pointer to a new GstXML object.

 */

GstXML *

gst_xml_new (void)

{

  return GST_XML (g_object_new (GST_TYPE_XML, NULL));

}

/**

 * gst_xml_write:

 * @element: The element to write out

 *

 * Converts the given element into an XML presentation.

 *

 * Returns: a pointer to an XML document

 */

xmlDocPtr

gst_xml_write (GstElement * element)

{

  xmlDocPtr doc;

  xmlNodePtr elementnode;

  xmlNsPtr gst_ns;

  doc = xmlNewDoc ((xmlChar *) "1.0");

  doc->xmlRootNode = xmlNewDocNode (doc, NULL, (xmlChar *) "gstreamer", NULL);

  gst_ns =

      xmlNewNs (doc->xmlRootNode,

      (xmlChar *) "http://gstreamer.net/gst-core/1.0/", (xmlChar *) "gst");

  elementnode = xmlNewChild (doc->xmlRootNode, gst_ns, (xmlChar *) "element",

      NULL);

  gst_object_save_thyself (GST_OBJECT (element), elementnode);

  return doc;

}

/**

 * gst_xml_write_file:

 * @element: The element to write out

 * @out: an open file, like stdout

 *

 * Converts the given element into XML and writes the formatted XML to an open

 * file.

 *

 * Returns: number of bytes written on success, -1 otherwise.

 */

gint

gst_xml_write_file (GstElement * element, FILE * out)

{

  xmlDocPtr cur;

#ifdef HAVE_LIBXML2

  xmlOutputBufferPtr buf;

#endif

  const char *encoding;

  xmlCharEncodingHandlerPtr handler = NULL;

  int indent;

  gboolean ret;

  cur = gst_xml_write (element);

  if (!cur)

    return -1;

#ifdef HAVE_LIBXML2

  encoding = (const char *) cur->encoding;

  if (encoding != NULL) {

    xmlCharEncoding enc;

    enc = xmlParseCharEncoding (encoding);

    if (cur->charset != XML_CHAR_ENCODING_UTF8) {

      xmlGenericError (xmlGenericErrorContext,

          "xmlDocDump: document not in UTF8\n");

      return -1;

    }

    if (enc != XML_CHAR_ENCODING_UTF8) {

      handler = xmlFindCharEncodingHandler (encoding);

      if (handler == NULL) {

        xmlFree ((char *) cur->encoding);

        cur->encoding = NULL;

      }

    }

  }

  buf = xmlOutputBufferCreateFile (out, handler);

  indent = xmlIndentTreeOutput;

  xmlIndentTreeOutput = 1;

  ret = xmlSaveFormatFileTo (buf, cur, NULL, 1);

  xmlIndentTreeOutput = indent;

#else

  /* apparently this doesn't return anything in libxml1 */

  xmlDocDump (out, cur);

  ret = 1;

#endif

  return ret;

}

/**

 * gst_xml_parse_doc:

 * @xml: a pointer to a GstXML object

 * @doc: a pointer to an xml document to parse

 * @root: The name of the root object to build

 *

 * Fills the GstXML object with the elements from the

 * xmlDocPtr.

 *

 * Returns: TRUE on success, FALSE otherwise

 */

gboolean

gst_xml_parse_doc (GstXML * xml, xmlDocPtr doc, const guchar * root)

{

  xmlNodePtr field, cur;

  xmlNsPtr ns;

  cur = xmlDocGetRootElement (doc);

  if (cur == NULL) {

    g_warning ("gstxml: empty document\n");

    return FALSE;

  }

  ns = xmlSearchNsByHref (doc, cur,

      (xmlChar *) "http://gstreamer.net/gst-core/1.0/");

  if (ns == NULL) {

    g_warning ("gstxml: document of wrong type, core namespace not found\n");

    return FALSE;

  }

  if (strcmp ((char *) cur->name, "gstreamer")) {

    g_warning ("gstxml: XML file is in wrong format\n");

    return FALSE;

  }

  gst_class_signal_connect (GST_OBJECT_CLASS (G_OBJECT_GET_CLASS (xml)),

      "object_loaded", (gpointer) gst_xml_object_loaded, xml);

  xml->ns = ns;

  field = cur->xmlChildrenNode;

  while (field) {

    if (!strcmp ((char *) field->name, "element") && (field->ns == xml->ns)) {

      GstElement *element;

      element = gst_xml_make_element (field, NULL);

      xml->topelements = g_list_prepend (xml->topelements, element);

    }

    field = field->next;

  }

  xml->topelements = g_list_reverse (xml->topelements);

  return TRUE;

}

/* FIXME 0.9: Why guchar*? */

/**

 * gst_xml_parse_file:

 * @xml: a pointer to a GstXML object

 * @fname: The filename with the xml description

 * @root: The name of the root object to build

 *

 * Fills the GstXML object with the corresponding elements from

 * the XML file fname. Optionally it will only build the element from

 * the element node root (if it is not NULL). This feature is useful

 * if you only want to build a specific element from an XML file

 * but not the pipeline it is embedded in.

 *

 * Pass "-" as fname to read from stdin. You can also pass a URI

 * of any format that libxml supports, including http.

 *

 * Returns: TRUE on success, FALSE otherwise

 */

gboolean

gst_xml_parse_file (GstXML * xml, const guchar * fname, const guchar * root)

{

  xmlDocPtr doc;

  gboolean ret;

  g_return_val_if_fail (fname != NULL, FALSE);

  doc = xmlParseFile ((char *) fname);

  if (!doc) {

    g_warning ("gstxml: XML file \"%s\" could not be read\n", fname);

    return FALSE;

  }

  ret = gst_xml_parse_doc (xml, doc, root);

  xmlFreeDoc (doc);

  return ret;

}

/* FIXME 0.9: guchar* */

/**

 * gst_xml_parse_memory:

 * @xml: a pointer to a GstXML object

 * @buffer: a pointer to the in memory XML buffer

 * @size: the size of the buffer

 * @root: the name of the root objects to build

 *

 * Fills the GstXML object with the corresponding elements from

 * an in memory XML buffer.

 *

 * Returns: TRUE on success

 */

gboolean

gst_xml_parse_memory (GstXML * xml, guchar * buffer, guint size,

    const gchar * root)

{

  xmlDocPtr doc;

  gboolean ret;

  g_return_val_if_fail (buffer != NULL, FALSE);

  doc = xmlParseMemory ((char *) buffer, size);

  ret = gst_xml_parse_doc (xml, doc, (const xmlChar *) root);

  xmlFreeDoc (doc);

  return ret;

}

static void

gst_xml_object_loaded (GstObject * private, GstObject * object, xmlNodePtr self,

    gpointer data)

{

  GstXML *xml = GST_XML (data);

  /* FIXME check that this element was created from the same xmlDocPtr... */

  g_signal_emit (G_OBJECT (xml), gst_xml_signals[OBJECT_LOADED], 0, object,

      self);

}

/**

 * gst_xml_get_topelements:

 * @xml: The GstXML to get the elements from

 *

 * Retrieve a list of toplevel elements.

 *

 * Returns: a GList of top-level elements. The caller does not own a copy

 * of the list and must not free or modify the list. The caller also does not

 * own a reference to any of the elements in the list and should obtain its own

 * reference using gst_object_ref() if necessary.

 */

GList *

gst_xml_get_topelements (GstXML * xml)

{

  g_return_val_if_fail (xml != NULL, NULL);

  return xml->topelements;

}

/* FIXME 0.11: why is the arg guchar* instead of gchar*? */

/**

 * gst_xml_get_element:

 * @xml: The GstXML to get the element from

 * @name: The name of element to retrieve

 *

 * This function is used to get a pointer to the GstElement corresponding

 * to name in the pipeline description. You would use this if you have

 * to do anything to the element after loading.

 *

 * Returns: a pointer to a new GstElement, caller owns returned reference.

 */

GstElement *

gst_xml_get_element (GstXML * xml, const guchar * name)

{

  GstElement *element;

  GList *topelements;

  g_return_val_if_fail (xml != NULL, NULL);

  g_return_val_if_fail (name != NULL, NULL);

  GST_DEBUG ("gstxml: getting element \"%s\"", name);

  topelements = gst_xml_get_topelements (xml);

  while (topelements) {

    GstElement *top = GST_ELEMENT (topelements->data);

    GST_DEBUG ("gstxml: getting element \"%s\"", name);

    if (!strcmp (GST_ELEMENT_NAME (top), (char *) name)) {

      return GST_ELEMENT_CAST (gst_object_ref (top));

    } else {

      if (GST_IS_BIN (top)) {

        element = gst_bin_get_by_name (GST_BIN (top), (gchar *) name);

        if (element)

          return element;

      }

    }

    topelements = g_list_next (topelements);

  }

  return NULL;

}

/**

 * gst_xml_make_element:

 * @cur: the xml node

 * @parent: the parent of this object when it's loaded

 *

 * Load the element from the XML description

 *

 * Returns: the new element

 */

GstElement *

gst_xml_make_element (xmlNodePtr cur, GstObject * parent)

{

  xmlNodePtr children = cur->xmlChildrenNode;

  GstElement *element;

  gchar *name = NULL;

  gchar *type = NULL;

  /* first get the needed tags to construct the element */

  while (children) {

    if (!strcmp ((char *) children->name, "name")) {

      name = (gchar *) xmlNodeGetContent (children);

    } else if (!strcmp ((char *) children->name, "type")) {

      type = (gchar *) xmlNodeGetContent (children);

    }

    children = children->next;

  }

  g_return_val_if_fail (name != NULL, NULL);

  g_return_val_if_fail (type != NULL, NULL);

  GST_CAT_INFO (GST_CAT_XML, "loading \"%s\" of type \"%s\"", name, type);

  element = gst_element_factory_make (type, name);

  g_return_val_if_fail (element != NULL, NULL);

  g_free (type);

  g_free (name);

  /* ne need to set the parent on this object bacause the pads */

  /* will go through the hierarchy to link to their peers */

  if (parent) {

    if (GST_IS_BIN (parent)) {

      gst_bin_add (GST_BIN (parent), element);

    } else {

      gst_object_set_parent (GST_OBJECT (element), parent);

    }

  }

  gst_object_restore_thyself (GST_OBJECT (element), cur);

  return element;

}