/*****************************************************************************

 * libxml.c: XML parser using libxml2

 *****************************************************************************

 * Copyright (C) 2004 VLC authors and VideoLAN

 *

 * Authors: Gildas Bazin <gbazin@videolan.org>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or

 * (at your option) any later version.

 *

 * This program 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 Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.

 *****************************************************************************/

#ifdef HAVE_CONFIG_H

# include "config.h"

#endif

#include <vlc_common.h>

#include <vlc_plugin.h>

#include <vlc_block.h>

#include <vlc_stream.h>

#include <vlc_xml.h>

#include <libxml/xmlreader.h>

#include <libxml/catalog.h>

/*****************************************************************************

 * Catalogue functions

 *****************************************************************************/

static void CatalogLoad( xml_t *p_xml, const char *psz_filename )

{

    VLC_UNUSED(p_xml);

    if( !psz_filename ) xmlInitializeCatalog();

    else xmlLoadCatalog( psz_filename );

}

static void CatalogAdd( xml_t *p_xml, const char *psz_arg1,

                          const char *psz_arg2, const char *psz_filename )

{

    VLC_UNUSED(p_xml);

    xmlCatalogAdd( (unsigned char*)psz_arg1, (unsigned char*)psz_arg2,

        (unsigned char*)psz_filename );

}

static vlc_mutex_t lock = VLC_STATIC_MUTEX;

/*****************************************************************************

 * Module initialization

 *****************************************************************************/

static int Open( vlc_object_t *p_this )

{

    xml_t *p_xml = (xml_t *)p_this;

    if( !xmlHasFeature( XML_WITH_THREAD ) )

        return VLC_EGENERIC;

    vlc_mutex_lock( &lock );

    xmlInitParser();

    vlc_mutex_unlock( &lock );

    p_xml->pf_catalog_load = CatalogLoad;

    p_xml->pf_catalog_add  = CatalogAdd;

    return VLC_SUCCESS;

}

/*****************************************************************************

 * Module deinitialization

 *****************************************************************************/

static void Close( vlc_object_t *p_this )

{

    /* /!\

     * In theory, xmlCleanupParser() should be called here.

     * Unfortunately that function is not thread-safe,

     * operating on global state. So even if we would be

     * able to know when this module is unloaded, we could

     * still not call it then, as other libraries or the apps

     * using libVLC could still use libxml themselves.

     *

     * Citing the libxml docs for xmlCleanupParser:

     *

     * > If your application is multithreaded or has plugin support

     * > calling this may crash the application if another thread or

     * > a plugin is still using libxml2. It's sometimes very hard to

     * > guess if libxml2 is in use in the application, some libraries

     * > or plugins may use it without notice. In case of doubt abstain

     * > from calling this function or do it just before calling exit()

     * > to avoid leak reports from valgrind!

     */

    VLC_UNUSED(p_this);

}

/*****************************************************************************

 * Reader functions

 *****************************************************************************/

static void ReaderErrorHandler( void *p_arg, const char *p_msg,

                                xmlParserSeverities severity,

                                xmlTextReaderLocatorPtr locator)

{

    VLC_UNUSED(severity);

    xml_reader_t *p_reader = (xml_reader_t *)p_arg;

    int line = xmlTextReaderLocatorLineNumber( locator );

    msg_Err( p_reader, "XML parser error (line %d) : %s", line, p_msg );

}

typedef struct

{

    xmlTextReaderPtr xml;

    char *node;

    char *namespace;

} xml_reader_sys_t;

static int ReaderUseDTD ( xml_reader_t *p_reader )

{

    /* Activate DTD validation */

    xml_reader_sys_t *p_sys = p_reader->p_sys;

    xmlTextReaderSetParserProp( p_sys->xml,

                                XML_PARSER_DEFAULTATTRS, true );

    xmlTextReaderSetParserProp( p_sys->xml,

                                XML_PARSER_VALIDATE, true );

    return VLC_SUCCESS;

}

static int ReaderNextNode( xml_reader_t *p_reader, const char **pval,

                             const char **pnamespace )

{

    xml_reader_sys_t *p_sys = p_reader->p_sys;

    const xmlChar *node, *namespace = NULL;

    int ret;

    skip:

    free( p_sys->node );

    free( p_sys->namespace );

    p_sys->node = NULL;

    p_sys->namespace = NULL;

    switch( xmlTextReaderRead( p_sys->xml ) )

    {

        case 0: /* EOF */

            return XML_READER_NONE;

        case -1: /* error */

            return XML_READER_ERROR;

    }

    switch( xmlTextReaderNodeType( p_sys->xml ) )

    {

        case XML_READER_TYPE_ELEMENT:

            node = xmlTextReaderConstName( p_sys->xml );

            namespace = xmlTextReaderConstNamespaceUri( p_sys->xml );

            ret = XML_READER_STARTELEM;

            break;

        case XML_READER_TYPE_END_ELEMENT:

            node = xmlTextReaderConstName( p_sys->xml );

            namespace = xmlTextReaderConstNamespaceUri( p_sys->xml );

            ret = XML_READER_ENDELEM;

            break;

        case XML_READER_TYPE_CDATA:

        case XML_READER_TYPE_TEXT:

            node = xmlTextReaderConstValue( p_sys->xml );

            ret = XML_READER_TEXT;

            break;

        case -1:

            return XML_READER_ERROR;

        default:

            goto skip;

    }

    if( unlikely(node == NULL) )

        return XML_READER_ERROR;

    p_sys->node = strdup( (const char *) node );

    if( namespace )

        p_sys->namespace = strdup( (const char *) namespace );

    if( pval != NULL )

        *pval = p_sys->node;

    if( pnamespace != NULL )

        *pnamespace = p_sys->namespace;

    return likely(p_sys->node != NULL) ? ret : XML_READER_ERROR;

}

static const char *ReaderNextAttr( xml_reader_t *p_reader, const char **pval,

                                     const char **pnamespace )

{

    xml_reader_sys_t *p_sys = p_reader->p_sys;

    xmlTextReaderPtr xml = p_sys->xml;

    const xmlChar *name, *value;

    if( xmlTextReaderMoveToNextAttribute( xml ) != 1

     || (name = xmlTextReaderConstName( xml )) == NULL

     || (value = xmlTextReaderConstValue( xml )) == NULL )

        return NULL;

    if( pnamespace )

        *pnamespace = (const char *) xmlTextReaderConstNamespaceUri( xml );

    *pval = (const char *)value;

    return (const char *) name;

}

static int StreamRead( void *p_context, char *p_buffer, int i_buffer )

{

    stream_t *s = (stream_t*)p_context;

    return vlc_stream_Read( s, p_buffer, i_buffer );

}

static int ReaderIsEmptyElement( xml_reader_t *p_reader )

{

    xml_reader_sys_t *p_sys = p_reader->p_sys;

    return xmlTextReaderIsEmptyElement( p_sys->xml );

}

static int ReaderOpen( vlc_object_t *p_this )

{

    if( !xmlHasFeature( XML_WITH_THREAD ) )

        return VLC_EGENERIC;

    xml_reader_t *p_reader = (xml_reader_t *)p_this;

    xml_reader_sys_t *p_sys = malloc( sizeof( *p_sys ) );

    xmlTextReaderPtr p_libxml_reader;

    if( unlikely(!p_sys) )

        return VLC_ENOMEM;

    vlc_mutex_lock( &lock );

    xmlInitParser();

    vlc_mutex_unlock( &lock );

    p_libxml_reader = xmlReaderForIO( StreamRead, NULL, p_reader->p_stream,

                                      NULL, NULL, 0 );

    if( !p_libxml_reader )

    {

        free( p_sys );

        /* /!\

         * xmlCleanupParser should but can't be called here,

         * for the same reason as in Close().

         */

        return VLC_ENOMEM;

    }

    /* Set the error handler */

    xmlTextReaderSetErrorHandler( p_libxml_reader,

                                  ReaderErrorHandler, p_reader );

    p_sys->xml = p_libxml_reader;

    p_sys->node = NULL;

    p_sys->namespace = NULL;

    p_reader->p_sys = p_sys;

    p_reader->pf_next_node = ReaderNextNode;

    p_reader->pf_next_attr = ReaderNextAttr;

    p_reader->pf_is_empty = ReaderIsEmptyElement;

    p_reader->pf_use_dtd = ReaderUseDTD;

    return VLC_SUCCESS;

}

static void ReaderClose( vlc_object_t *p_this )

{

    xml_reader_t *p_reader = (xml_reader_t *)p_this;

    xml_reader_sys_t *p_sys = p_reader->p_sys;

    xmlFreeTextReader( p_sys->xml );

    free( p_sys->node );

    free( p_sys->namespace );

    free( p_sys );

    /* /!\

     * xmlCleanupParser should but can't be called here,

     * same reason as in Close() of the main xml module.

     */

}

vlc_module_begin ()

    set_description( N_("XML Parser (using libxml2)") )

    set_capability( "xml", 10 )

    set_callbacks( Open, Close )

#ifdef _WIN32

    cannot_unload_broken_library()

#endif

    add_submodule()

    set_capability( "xml reader", 10 )

    set_callbacks( ReaderOpen, ReaderClose )

vlc_module_end ()