[melted] / src / modules / westley / producer_westley.c

/*
 * producer_westley.c -- a libxml2 parser of mlt service networks
 * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
 * Author: Dan Dennedy <dan@dennedy.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

// TODO: destroy unreferenced producers (they are currently destroyed
//       when the returned producer is closed).
// TODO: determine why deserialise_context can not be released.

#include "producer_westley.h"
#include <framework/mlt.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include <libxml/parser.h>
#include <libxml/parserInternals.h> // for xmlCreateFileParserCtxt
#include <libxml/tree.h>

#define STACK_SIZE 1000

struct deserialise_context_s
{
        mlt_service stack_service[ STACK_SIZE ];
        int stack_service_size;
        mlt_properties producer_map;
        mlt_properties destructors;
        char *property;
        mlt_properties producer_properties;
        int is_value;
        xmlDocPtr value_doc;
        xmlNodePtr stack_node[ STACK_SIZE ];
        int stack_node_size;
        xmlDocPtr entity_doc;
};
typedef struct deserialise_context_s *deserialise_context;


/** Push a service.
*/

static int context_push_service( deserialise_context this, mlt_service that )
{
        int ret = this->stack_service_size >= STACK_SIZE - 1;
        if ( ret == 0 )
                this->stack_service[ this->stack_service_size ++ ] = that;
        return ret;
}

/** Pop a service.
*/

static mlt_service context_pop_service( deserialise_context this )
{
        mlt_service result = NULL;
        if ( this->stack_service_size > 0 )
                result = this->stack_service[ -- this->stack_service_size ];
        return result;
}

/** Push a node.
*/

static int context_push_node( deserialise_context this, xmlNodePtr node )
{
        int ret = this->stack_node_size >= STACK_SIZE - 1;
        if ( ret == 0 )
                this->stack_node[ this->stack_node_size ++ ] = node;
        return ret;
}

/** Pop a node.
*/

static xmlNodePtr context_pop_node( deserialise_context this )
{
        xmlNodePtr result = NULL;
        if ( this->stack_node_size > 0 )
                result = this->stack_node[ -- this->stack_node_size ];
        return result;
}


// Set the destructor on a new service
static void track_service( mlt_properties properties, void *service, mlt_destructor destructor )
{
        int registered = mlt_properties_get_int( properties, "registered" );
        char *key = mlt_properties_get( properties, "registered" );
        mlt_properties_set_data( properties, key, service, 0, destructor, NULL );
        mlt_properties_set_int( properties, "registered", ++ registered );
}


// Forward declarations
static void on_end_track( deserialise_context context, const xmlChar *name );
static void on_end_entry( deserialise_context context, const xmlChar *name );

static void on_start_tractor( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_service service = mlt_tractor_service( mlt_tractor_init() );
        mlt_properties properties = mlt_service_properties( service );

        track_service( context->destructors, service, (mlt_destructor) mlt_tractor_close );

        mlt_properties_set_position( properties, "length", 0 );

        for ( ; atts != NULL && *atts != NULL; atts += 2 )
                mlt_properties_set( mlt_service_properties( service ), (char*) atts[0], (char*) atts[1] );

        if ( mlt_properties_get_position( properties, "length" ) < mlt_properties_get_position( properties, "out" ) )
        {
                mlt_position length = mlt_properties_get_position( properties, "out" ) + 1;
                mlt_properties_set_position( properties, "length", length );
        }

        if ( mlt_properties_get( properties, "id" ) != NULL )
                mlt_properties_set_data( context->producer_map, mlt_properties_get( properties, "id" ), service, 0, NULL, NULL );
        
        context_push_service( context, service );
}

static void on_start_multitrack( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_service service = mlt_multitrack_service( mlt_multitrack_init() );
        mlt_properties properties = mlt_service_properties( service );

        track_service( context->destructors, service, (mlt_destructor) mlt_multitrack_close );

        mlt_properties_set_position( properties, "length", 0 );

        for ( ; atts != NULL && *atts != NULL; atts += 2 )
                mlt_properties_set( properties, (char*) atts[0], (char*) atts[1] );

        if ( mlt_properties_get( properties, "id" ) != NULL )
                mlt_properties_set_data( context->producer_map, mlt_properties_get( properties, "id" ), service, 0, NULL, NULL );

        context_push_service( context, service );
}

static void on_start_playlist( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_service service = mlt_playlist_service( mlt_playlist_init() );
        mlt_properties properties = mlt_service_properties( service );

        track_service( context->destructors, service, (mlt_destructor) mlt_playlist_close );

        mlt_properties_set_position( properties, "length", 0 );

        for ( ; atts != NULL && *atts != NULL; atts += 2 )
        {
                mlt_properties_set( properties, ( char* )atts[0], ( char* )atts[1] );

                // Out will be overwritten later as we append, so we need to save it
                if ( strcmp( atts[ 0 ], "out" ) == 0 )
                        mlt_properties_set( properties, "_westley.out", ( char* )atts[ 1 ] );
        }

        if ( mlt_properties_get( properties, "id" ) != NULL )
                mlt_properties_set_data( context->producer_map, mlt_properties_get( properties, "id" ), service, 0, NULL, NULL );

        context_push_service( context, service );
}

static void on_start_producer( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_properties properties = context->producer_properties = mlt_properties_new();

        for ( ; atts != NULL && *atts != NULL; atts += 2 )
        {
                mlt_properties_set( properties, (char*) atts[0], (char*) atts[1] );
        }
}

static void on_start_blank( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        // Get the playlist from the stack
        mlt_service service = context_pop_service( context );
        mlt_position length = 0;
        
        if ( service == NULL )
                return;
        
        // Look for the length attribute
        for ( ; atts != NULL && *atts != NULL; atts += 2 )
        {
                if ( strcmp( atts[0], "length" ) == 0 )
                {
                        length = atoll( atts[1] );
                        break;
                }
        }

        // Append a blank to the playlist
        mlt_playlist_blank( MLT_PLAYLIST( service ), length - 1 );

        // Push the playlist back onto the stack
        context_push_service( context, service );
}

static void on_start_entry_track( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        // Use a dummy service to hold properties to allow arbitrary nesting
        mlt_service service = calloc( 1, sizeof( struct mlt_service_s ) );
        mlt_service_init( service, NULL );

        // Push the dummy service onto the stack
        context_push_service( context, service );
        
        for ( ; atts != NULL && *atts != NULL; atts += 2 )
        {
                mlt_properties_set( mlt_service_properties( service ), (char*) atts[0], (char*) atts[1] );
                
                // Look for the producer attribute
                if ( strcmp( atts[ 0 ], "producer" ) == 0 )
                {
                        if ( mlt_properties_get_data( context->producer_map, (char*) atts[1], NULL ) !=  NULL )
                                // Push the referenced producer onto the stack
                                context_push_service( context, MLT_SERVICE( mlt_properties_get_data( context->producer_map, (char*) atts[1], NULL ) ) );
                }
        }
}

static void on_start_filter( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_properties properties = context->producer_properties = mlt_properties_new();

        // Set the properties
        for ( ; atts != NULL && *atts != NULL; atts += 2 )
                mlt_properties_set( properties, (char*) atts[0], (char*) atts[1] );
}

static void on_start_transition( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_properties properties = context->producer_properties = mlt_properties_new();

        // Set the properties
        for ( ; atts != NULL && *atts != NULL; atts += 2 )
                mlt_properties_set( properties, (char*) atts[0], (char*) atts[1] );
}

static void on_start_property( deserialise_context context, const xmlChar *name, const xmlChar **atts)
{
        mlt_properties properties = context->producer_properties;
        char *value = NULL;

        if ( properties == NULL )
                return;
        
        // Set the properties
        for ( ; atts != NULL && *atts != NULL; atts += 2 )
        {
                if ( strcmp( atts[ 0 ], "name" ) == 0 )
                {
                        context->property = strdup( atts[ 1 ] );
                }
                else if ( strcmp( atts[ 0 ], "value" ) == 0 )
                {
                        value = (char*) atts[ 1 ];
                }
        }

        if ( context->property != NULL && value != NULL )
                mlt_properties_set( properties, context->property, value );
        
        // Tell parser to collect any further nodes for serialisation
        context->is_value = 1;
}


/** This function adds a producer to a playlist or multitrack when
    there is no entry or track element.
*/

static int add_producer( deserialise_context context, mlt_service service, mlt_position in, mlt_position out )
{
        // Get the parent producer
        mlt_service producer = context_pop_service( context );
        if ( producer != NULL )
        {
                char *resource = mlt_properties_get( mlt_service_properties( producer ), "resource" );
                
                // Put the parent producer back
                context_push_service( context, producer );
                        
                // If the parent producer is a multitrack or playlist (not a track or entry)
                if ( resource && ( strcmp( resource, "<playlist>" ) == 0 ||
                        strcmp( resource, "<multitrack>" ) == 0 ) )
                {
                        if ( strcmp( resource, "<playlist>" ) == 0 )
                        {
                                // Append this producer to the playlist
                                mlt_playlist_append_io( MLT_PLAYLIST( producer ), 
                                        MLT_PRODUCER( service ), in, out );
                        }
                        else
                        {
                                // Set this producer on the multitrack
                                mlt_multitrack_connect( MLT_MULTITRACK( producer ),
                                        MLT_PRODUCER( service ),
                                        mlt_multitrack_count( MLT_MULTITRACK( producer ) ) );
                        }
                        // Normally, the enclosing entry or track will pop this service off
                        // In its absence we do not push it on.
                        return 1;
                }
        }
        return 0;
}

static void on_end_multitrack( deserialise_context context, const xmlChar *name )
{
        // Get the multitrack from the stack
        mlt_service producer = context_pop_service( context );
        if ( producer == NULL )
                return;

        // Get the tractor from the stack
        mlt_service service = context_pop_service( context );
        
        // Create a tractor if one does not exist
        char *resource = NULL;
        if ( service != NULL )
                resource = mlt_properties_get( mlt_service_properties( service ), "resource" );
        if ( service == NULL || resource == NULL || strcmp( resource, "<tractor>" ) )
        {
                // Put the anonymous service back onto the stack!
                context_push_service( context, service );
                
                service = mlt_tractor_service( mlt_tractor_init() );
                track_service( context->destructors, service, (mlt_destructor) mlt_tractor_close );
                
                // Inherit the producer's properties
                mlt_properties properties = mlt_service_properties( service );
                mlt_properties_set_position( properties, "length", mlt_producer_get_out( MLT_PRODUCER( producer ) ) + 1 );
                mlt_producer_set_in_and_out( MLT_PRODUCER( service ), 0, mlt_producer_get_out( MLT_PRODUCER( producer ) ) );
                mlt_properties_set_double( properties, "fps", mlt_producer_get_fps( MLT_PRODUCER( producer ) ) );
        }
        
        // Connect the tractor to the multitrack
        mlt_tractor_connect( MLT_TRACTOR( service ), producer );
        mlt_properties_set_data( mlt_service_properties( service ), "multitrack",
                MLT_MULTITRACK( producer ), 0, NULL, NULL );

        // See if the producer should be added to a playlist or multitrack
        add_producer( context, service, 0, mlt_producer_get_out( MLT_PRODUCER( producer ) ) );
        
        // Always push the multitrack back onto the stack for filters and transitions
        context_push_service( context, producer );
        
        // Always push the tractor back onto the stack for filters and transitions
        context_push_service( context, service );
}

static void on_end_playlist( deserialise_context context, const xmlChar *name )
{
        // Get the playlist from the stack
        mlt_service producer = context_pop_service( context );
        mlt_properties properties = mlt_service_properties( producer );

        mlt_position in = mlt_properties_get_position( properties, "in" );
        mlt_position out;

        if ( mlt_properties_get( properties, "_westley.out" ) != NULL )
                out = mlt_properties_get_position( properties, "_westley.out" );
        else
                out = mlt_properties_get_position( properties, "length" ) - 1;

        if ( mlt_properties_get_position( properties, "length" ) < out )
                mlt_properties_set_position( properties, "length", out  + 1 );

        mlt_producer_set_in_and_out( MLT_PRODUCER( producer ), in, out );
        
        // See if the playlist should be added to a playlist or multitrack
        if ( add_producer( context, producer, in, out ) == 0 )
                
                // Otherwise, push the playlist back onto the stack
                context_push_service( context, producer );
}

static void on_end_track( deserialise_context context, const xmlChar *name )
{
        // Get the producer from the stack
        mlt_service producer = context_pop_service( context );
        if ( producer == NULL )
                return;

        // See if the producer is a tractor
        char *resource = mlt_properties_get( mlt_service_properties( producer ), "resource" );
        if ( resource && strcmp( resource, "<tractor>" ) == 0 )
                // If so chomp its producer
                context_pop_service( context );

        // Get the dummy track service from the stack
        mlt_service track = context_pop_service( context );
        if ( track == NULL )
        {
                context_push_service( context, producer );
                return;
        }

        // Get the multitrack from the stack
        mlt_service service = context_pop_service( context );
        if ( service == NULL )
        {
                context_push_service( context, producer );
                return;
        }

        // Set the track on the multitrack
        mlt_multitrack_connect( MLT_MULTITRACK( service ),
                MLT_PRODUCER( producer ),
                mlt_multitrack_count( MLT_MULTITRACK( service ) ) );

        // Set producer i/o if specified
        if ( mlt_properties_get( mlt_service_properties( track ), "in" ) != NULL ||
                mlt_properties_get( mlt_service_properties( track ), "out" ) != NULL )
        {
                mlt_producer_set_in_and_out( MLT_PRODUCER( producer ),
                        mlt_properties_get_position( mlt_service_properties( track ), "in" ),
                        mlt_properties_get_position( mlt_service_properties( track ), "out" ) );
        }

        // Push the multitrack back onto the stack
        context_push_service( context, service );

        mlt_service_close( track );
}

static void on_end_entry( deserialise_context context, const xmlChar *name )
{
        // Get the producer from the stack
        mlt_service producer = context_pop_service( context );
        if ( producer == NULL )
                return;
        
        // See if the producer is a tractor
        char *resource = mlt_properties_get( mlt_service_properties( producer ), "resource" );
        if ( resource && strcmp( resource, "<tractor>" ) == 0 )
                // If so chomp its producer
                context_pop_service( context );

        // Get the dummy entry service from the stack
        mlt_service entry = context_pop_service( context );
        if ( entry == NULL )
        {
                context_push_service( context, producer );
                return;
        }

        // Get the playlist from the stack
        mlt_service service = context_pop_service( context );
        if ( service == NULL )
        {
                context_push_service( context, producer );
                return;
        }

        // Append the producer to the playlist
        if ( mlt_properties_get( mlt_service_properties( entry ), "in" ) != NULL ||
                mlt_properties_get( mlt_service_properties( entry ), "out" ) != NULL )
        {
                mlt_playlist_append_io( MLT_PLAYLIST( service ),
                        MLT_PRODUCER( producer ),
                        mlt_properties_get_position( mlt_service_properties( entry ), "in" ), 
                        mlt_properties_get_position( mlt_service_properties( entry ), "out" ) );
        }
        else
        {
                mlt_playlist_append( MLT_PLAYLIST( service ), MLT_PRODUCER( producer ) );
        }

        // Push the playlist back onto the stack
        context_push_service( context, service );

        mlt_service_close( entry );
}

static void on_end_tractor( deserialise_context context, const xmlChar *name )
{
        // Get the tractor
        mlt_service tractor = context_pop_service( context );
        if ( tractor == NULL )
                return;
        
        // Get the tractor's multitrack
        mlt_producer multitrack = mlt_properties_get_data( mlt_service_properties( tractor ), "multitrack", NULL );
        if ( multitrack != NULL )
        {
                // Inherit the producer's properties
                mlt_properties properties = mlt_producer_properties( MLT_PRODUCER( tractor ) );
                mlt_properties_set_position( properties, "length", mlt_producer_get_out( multitrack ) + 1 );
                mlt_producer_set_in_and_out( multitrack, 0, mlt_producer_get_out( multitrack ) );
                mlt_properties_set_double( properties, "fps", mlt_producer_get_fps( multitrack ) );
        }

        // See if the tractor should be added to a playlist or multitrack
        if ( add_producer( context, tractor, 0, mlt_producer_get_out( MLT_PRODUCER( tractor ) ) ) == 0 )
                
                // Otherwise, push the tractor back onto the stack
                context_push_service( context, tractor );
}

static void on_end_property( deserialise_context context, const xmlChar *name )
{
        // Tell parser to stop building a tree
        context->is_value = 0;
        
        // See if there is a xml tree for the value
        if ( context->property != NULL && context->value_doc != NULL )
        {
                xmlChar *value;
                int size;
                
                // Serialise the tree to get value
                xmlDocDumpMemory( context->value_doc, &value, &size );
                mlt_properties_set( context->producer_properties, context->property, value );
                xmlFree( value );
                xmlFreeDoc( context->value_doc );
                context->value_doc = NULL;
        }
        
        // Close this property handling
        free( context->property );
        context->property = NULL;
}

static void on_end_producer( deserialise_context context, const xmlChar *name )
{
        mlt_properties properties = context->producer_properties;
        mlt_service service = NULL;
        
        if ( properties == NULL )
                return;
                
        char *resource = mlt_properties_get( properties, "resource" );
        // Let Kino-SMIL src be a synonym for resource
        if ( resource == NULL )
                resource = mlt_properties_get( properties, "src" );
        
        // Instantiate the producer
        if ( mlt_properties_get( properties, "mlt_service" ) != NULL )
        {
                service = MLT_SERVICE( mlt_factory_producer( "fezzik", mlt_properties_get( properties, "mlt_service" ) ) );
        }
        if ( service == NULL && resource != NULL )
        {
                char *root = mlt_properties_get( context->producer_map, "_root" );
                char *full_resource = malloc( strlen( root ) + strlen( resource ) + 1 );
                if ( resource[ 0 ] != '/' )
                {
                        strcpy( full_resource, root );
                        strcat( full_resource, resource );
                }
                else
                {
                        strcpy( full_resource, resource );
                }
                service = MLT_SERVICE( mlt_factory_producer( "fezzik", full_resource ) );
                free( full_resource );
        }
        if ( service == NULL )
                return;
        track_service( context->destructors, service, (mlt_destructor) mlt_producer_close );

        // Add the producer to the producer map
        if ( mlt_properties_get( properties, "id" ) != NULL )
                mlt_properties_set_data( context->producer_map, mlt_properties_get( properties, "id" ), service, 0, NULL, NULL );

        // Handle in/out properties separately
        mlt_position in = -1;
        mlt_position out = -1;
        
        // Get in
        if ( mlt_properties_get( properties, "in" ) != NULL )
                in = mlt_properties_get_position( properties, "in" );
        // Let Kino-SMIL clipBegin be a synonym for in
        if ( mlt_properties_get( properties, "clipBegin" ) != NULL )
                in = mlt_properties_get_position( properties, "clipBegin" );
        // Get out
        if ( mlt_properties_get( properties, "out" ) != NULL )
                out = mlt_properties_get_position( properties, "out" );
        // Let Kino-SMIL clipEnd be a synonym for out
        if ( mlt_properties_get( properties, "clipEnd" ) != NULL )
                out = mlt_properties_get_position( properties, "clipEnd" );
        
        // Remove in and out
        mlt_properties_set( properties, "in", NULL );
        mlt_properties_set( properties, "out", NULL );
        
        mlt_properties_inherit( mlt_service_properties( service ), properties );
        mlt_properties_close( properties );
        context->producer_properties = NULL;

        // See if the producer should be added to a playlist or multitrack
        if ( add_producer( context, service, in, out ) == 0 )
        {
                // Otherwise, set in and out on...
                if ( in != -1 || out != -1 )
                {
                        // Get the parent service
                        mlt_service parent = context_pop_service( context );
                        if ( parent != NULL )
                        {
                                // Get the parent properties
                                properties = mlt_service_properties( parent );
                                
                                char *resource = mlt_properties_get( properties, "resource" );
                                
                                // Put the parent producer back
                                context_push_service( context, parent );
                                        
                                // If the parent is a track or entry
                                if ( resource && ( strcmp( resource, "<entry_track>" ) == 0 ) )
                                {
                                        mlt_properties_set_position( properties, "in", in );
                                        mlt_properties_set_position( properties, "out", out );
                                }
                                else
                                {
                                        // Otherwise, set in and out on producer directly
                                        mlt_producer_set_in_and_out( MLT_PRODUCER( service ), in, out );
                                }
                        }
                        else
                        {
                                // Otherwise, set in and out on producer directly
                                mlt_producer_set_in_and_out( MLT_PRODUCER( service ), in, out );
                        }
                }
        
                // Push the producer onto the stack
                context_push_service( context, service );
        }
}

static void on_end_filter( deserialise_context context, const xmlChar *name )
{
        mlt_properties properties = context->producer_properties;
        if ( properties == NULL )
                return;

        char *id;
        char key[11];
        key[ 10 ] = '\0';
        mlt_service tractor = NULL;
        
        // Get the producer from the stack
        mlt_service producer = context_pop_service( context );
        if ( producer == NULL )
                return;
        
        // See if the producer is a tractor
        char *resource = mlt_properties_get( mlt_service_properties( producer ), "resource" );
        if ( resource != NULL && strcmp( resource, "<tractor>" ) == 0 )
        {
                // If so, then get the next producer
                tractor = producer;
                producer = context_pop_service( context );
        }
        
//fprintf( stderr, "connecting filter to %s\n", mlt_properties_get( mlt_service_properties( producer ), "resource" ) );

        // Create the filter
        mlt_service service = MLT_SERVICE( mlt_factory_filter( mlt_properties_get( properties, "mlt_service" ), NULL ) );
        if ( service == NULL )
        {
                context_push_service( context, producer );
                return;
        }
        track_service( context->destructors, service, (mlt_destructor) mlt_filter_close );

        // Connect the filter to the producer
        mlt_filter_connect( MLT_FILTER( service ), producer,
                mlt_properties_get_int( properties, "track" ) );

        // Set in and out from producer if non existant
        if ( mlt_properties_get( properties, "in" ) == NULL )
                mlt_properties_set_position( properties, "in", mlt_producer_get_in( MLT_PRODUCER( producer ) ) );
        if ( mlt_properties_get( properties, "out" ) == NULL )
                mlt_properties_set_position( properties, "out", mlt_producer_get_out( MLT_PRODUCER( producer ) ) );

        // Propogate the properties
        mlt_properties_inherit( mlt_service_properties( service ), properties );
        mlt_properties_close( properties );
        context->producer_properties = NULL;
        properties = mlt_service_properties( service );

        // Set in and out again due to inheritance
        mlt_filter_set_in_and_out( MLT_FILTER( service ), 
                mlt_properties_get_position( properties, "in" ),
                mlt_properties_get_position( properties, "out" ) );

        // If a producer alias is in the producer_map, get it
        snprintf( key, 10, "%p", producer );
        if ( mlt_properties_get_data( context->producer_map, key, NULL ) != NULL )
                producer = mlt_properties_get_data( context->producer_map, key, NULL );

        // Put the producer in the producer map
        id = mlt_properties_get( mlt_service_properties( producer ), "id" );
        if ( id != NULL )
                mlt_properties_set_data( context->producer_map, id, service, 0, NULL, NULL );

        // For filter chain support, add an alias to the producer map
        snprintf( key, 10, "%p", service );
        mlt_properties_set_data( context->producer_map, key, producer, 0, NULL, NULL );
        
        // Push the filter onto the stack
        context_push_service( context, service );
        
        if ( tractor != NULL )
        {
                // Connect the tractor to the filter
                mlt_tractor_connect( MLT_TRACTOR( tractor ), service );

                // Push the tractor back onto the stack
                context_push_service( context, tractor );
        }
}

static void on_end_transition( deserialise_context context, const xmlChar *name )
{
        mlt_service tractor = NULL;
        mlt_properties properties = context->producer_properties;
        if ( properties == NULL )
                return;

        // Get the producer from the stack
        mlt_service producer = context_pop_service( context );
        if ( producer == NULL )
                return;

        // See if the producer is a tractor
        char *resource = mlt_properties_get( mlt_service_properties( producer ), "resource" );
        if ( resource != NULL && strcmp( resource, "<tractor>" ) == 0 )
        {
                // If so, then get the next producer
                tractor = producer;
                producer = context_pop_service( context );
        }
        
        // Create the transition
        mlt_service service = MLT_SERVICE( mlt_factory_transition( mlt_properties_get( properties, "mlt_service" ), NULL ) );
        if ( service == NULL )
        {
                context_push_service( context, producer );
                return;
        }
        track_service( context->destructors, service, (mlt_destructor) mlt_transition_close );

        // Propogate the properties
        mlt_properties_inherit( mlt_service_properties( service ), properties );
        mlt_properties_close( properties );
        context->producer_properties = NULL;
        properties = mlt_service_properties( service );

        // Set in and out again due to inheritance
        mlt_transition_set_in_and_out( MLT_TRANSITION( service ),
                mlt_properties_get_position( properties, "in" ),
                mlt_properties_get_position( properties, "out" ) );

        // Connect the transition to the producer
        mlt_transition_connect( MLT_TRANSITION( service ), producer,
                mlt_properties_get_int( properties, "a_track" ),
                mlt_properties_get_int( properties, "b_track" ) );

        // Push the transition onto the stack
        context_push_service( context, service );
        
        if ( tractor != NULL )
        {
                // Connect the tractor to the transition
                mlt_tractor_connect( MLT_TRACTOR( tractor ), service );

                // Push the tractor back onto the stack
                context_push_service( context, tractor );
        }
}

static void on_start_element( void *ctx, const xmlChar *name, const xmlChar **atts)
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );
        
        // Build a tree from nodes within a property value
        if ( context->is_value == 1 )
        {
                xmlNodePtr node = xmlNewNode( NULL, name );
                
                if ( context->value_doc == NULL )
                {
                        // Start a new tree
                        context->value_doc = xmlNewDoc( "1.0" );
                        xmlDocSetRootElement( context->value_doc, node );
                }
                else
                {
                        // Append child to tree
                        xmlAddChild( context->stack_node[ context->stack_node_size - 1 ], node );
                }
                context_push_node( context, node );
                
                // Set the attributes
                for ( ; atts != NULL && *atts != NULL; atts += 2 )
                        xmlSetProp( node, atts[ 0 ], atts[ 1 ] );
        }
        else if ( strcmp( name, "tractor" ) == 0 )
                on_start_tractor( context, name, atts );
        else if ( strcmp( name, "multitrack" ) == 0 )
                on_start_multitrack( context, name, atts );
        else if ( strcmp( name, "playlist" ) == 0 || strcmp( name, "seq" ) == 0 || strcmp( name, "smil" ) == 0 )
                on_start_playlist( context, name, atts );
        else if ( strcmp( name, "producer" ) == 0 || strcmp( name, "video" ) == 0 )
                on_start_producer( context, name, atts );
        else if ( strcmp( name, "blank" ) == 0 )
                on_start_blank( context, name, atts );
        else if ( strcmp( name, "entry" ) == 0 || strcmp( name, "track" ) == 0 )
                on_start_entry_track( context, name, atts );
        else if ( strcmp( name, "filter" ) == 0 )
                on_start_filter( context, name, atts );
        else if ( strcmp( name, "transition" ) == 0 )
                on_start_transition( context, name, atts );
        else if ( strcmp( name, "property" ) == 0 )
                on_start_property( context, name, atts );
}

static void on_end_element( void *ctx, const xmlChar *name )
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );
        
        if ( context->is_value == 1 && strcmp( name, "property" ) != 0 )
                context_pop_node( context );
        else if ( strcmp( name, "multitrack" ) == 0 )
                on_end_multitrack( context, name );
        else if ( strcmp( name, "playlist" ) == 0 || strcmp( name, "seq" ) == 0 || strcmp( name, "smil" ) == 0 )
                on_end_playlist( context, name );
        else if ( strcmp( name, "track" ) == 0 )
                on_end_track( context, name );
        else if ( strcmp( name, "entry" ) == 0 )
                on_end_entry( context, name );
        else if ( strcmp( name, "tractor" ) == 0 )
                on_end_tractor( context, name );
        else if ( strcmp( name, "property" ) == 0 )
                on_end_property( context, name );
        else if ( strcmp( name, "producer" ) == 0 || strcmp( name, "video" ) == 0 )
                on_end_producer( context, name );
        else if ( strcmp( name, "filter" ) == 0 )
                on_end_filter( context, name );
        else if ( strcmp( name, "transition" ) == 0 )
                on_end_transition( context, name );
}

static void on_characters( void *ctx, const xmlChar *ch, int len )
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );
        char *value = calloc( len + 1, 1 );

        value[ len ] = 0;
        strncpy( value, (const char*) ch, len );
        
        if ( context->stack_node_size > 0 )
                xmlNodeAddContent( context->stack_node[ context->stack_node_size - 1 ], ( xmlChar* )value );

        else if ( context->property != NULL && context->producer_properties != NULL )
                mlt_properties_set( context->producer_properties, context->property, value );
                
        free( value);
}

// The following 3 facilitate entity substitution in the SAX parser
static void on_internal_subset( void *ctx, const xmlChar* name,
        const xmlChar* publicId, const xmlChar* systemId )
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );
        
        xmlCreateIntSubset( context->entity_doc, name, publicId, systemId );
}

static void on_entity_declaration( void *ctx, const xmlChar* name, int type, 
        const xmlChar* publicId, const xmlChar* systemId, xmlChar* content)
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );
        
        xmlAddDocEntity( context->entity_doc, name, type, publicId, systemId, content );
}

xmlEntityPtr on_get_entity( void *ctx, const xmlChar* name )
{
        struct _xmlParserCtxt *xmlcontext = ( struct _xmlParserCtxt* )ctx;
        deserialise_context context = ( deserialise_context )( xmlcontext->_private );

        return xmlGetDocEntity( context->entity_doc, name );
}


mlt_producer producer_westley_init( char *filename )
{
        xmlSAXHandler *sax = calloc( 1, sizeof( xmlSAXHandler ) );
        struct deserialise_context_s *context = calloc( 1, sizeof( struct deserialise_context_s ) );
        mlt_properties properties = NULL;
        int i = 0;
        struct _xmlParserCtxt *xmlcontext;
        int well_formed = 0;
        
        context->producer_map = mlt_properties_new();
        context->destructors = mlt_properties_new();

        // We need to track the number of registered filters
        mlt_properties_set_int( context->destructors, "registered", 0 );

        // We need the directory prefix which was used for the westley
        mlt_properties_set( context->producer_map, "_root", "" );
        if ( strchr( filename, '/' ) )
        {
                char *root = NULL;
                mlt_properties_set( context->producer_map, "_root", filename );
                root = mlt_properties_get( context->producer_map, "_root" );
                *( strrchr( root, '/' ) + 1 ) = '\0';
        }

        // Setup SAX callbacks
        sax->startElement = on_start_element;
        sax->endElement = on_end_element;
        sax->characters = on_characters;
        sax->cdataBlock = on_characters;
        sax->internalSubset = on_internal_subset;
        sax->entityDecl = on_entity_declaration;
        sax->getEntity = on_get_entity;

        // Setup libxml2 SAX parsing
        xmlInitParser(); 
        xmlSubstituteEntitiesDefault( 1 );
        // This is used to facilitate entity substitution in the SAX parser
        context->entity_doc = xmlNewDoc( "1.0" );
        xmlcontext = xmlCreateFileParserCtxt( filename );
        xmlcontext->sax = sax;
        xmlcontext->_private = ( void* )context;
        
        // Parse
        xmlParseDocument( xmlcontext );
        well_formed = xmlcontext->wellFormed;
        
        // Cleanup after parsing
        xmlFreeDoc( context->entity_doc );
        free( sax );
        xmlcontext->sax = NULL;
        xmlcontext->_private = NULL;
        xmlFreeParserCtxt( xmlcontext );
        xmlMemoryDump( ); // for debugging

        // Get the last producer on the stack
        mlt_service service = context_pop_service( context );
        if ( well_formed && service != NULL )
        {
                // Verify it is a producer service (mlt_type="mlt_producer")
                // (producer, playlist, multitrack)
                char *type = mlt_properties_get( mlt_service_properties( service ), "mlt_type" );
                if ( type == NULL || ( strcmp( type, "mlt_producer" ) != 0 ) )
                        service = NULL;
        }

        if ( well_formed && service != NULL )
        {
                // Need the complete producer list for various reasons
                properties = context->destructors;

                // Now make sure we don't have a reference to the service in the properties
                for ( i = mlt_properties_count( properties ) - 1; i >= 1; i -- )
                {
                        char *name = mlt_properties_get_name( properties, i );
                        if ( mlt_properties_get_data( properties, name, NULL ) == service )
                        {
                                mlt_properties_set_data( properties, name, service, 0, NULL, NULL );
                                break;
                        }
                }

                // We are done referencing destructor property list
                // Set this var to service properties for convenience
                properties = mlt_service_properties( service );
        
                // make the returned service destroy the connected services
                mlt_properties_set_data( properties, "__destructors__", context->destructors, 0, (mlt_destructor) mlt_properties_close, NULL );

                // Now assign additional properties
                mlt_properties_set( properties, "resource", filename );

                // This tells consumer_westley not to deep copy
                mlt_properties_set( properties, "westley", "was here" );
        }
        else
        {
                // Return null if not well formed
                service = NULL;
                
                // Clean up
                mlt_properties_close( context->destructors );
        }

        free( context->stack_service );
        mlt_properties_close( context->producer_map );
        //free( context );

        return MLT_PRODUCER( service );
}