# -*- coding: utf-8 -*-
"""
Extracting possible embedded RDF/XML content from the file and parse it separately into the Graph. This is used, for example
by U{SVG 1.2 Tiny<http://www.w3.org/TR/SVGMobile12/>}.

@author: U{Ivan Herman<a href="http://www.w3.org/People/Ivan/">}
@license: This software is available for use under the
U{W3C® SOFTWARE NOTICE AND LICENSE<href="http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231">}
@contact: Ivan Herman, ivan@w3.org
@version: $Id: embeddedRDF.py,v 1.15 2012/11/16 17:51:53 ivan Exp $
"""

from io import StringIO

from .host import accept_embedded_rdf_xml, accept_embedded_turtle
from .utils import return_XML
import sys

def handle_embeddedRDF(node, graph, state):
    """
    Handles embedded RDF. There are two possibilities:
    
     - the file is one of the XML dialects that allows for an embedded RDF/XML portion. See the L{host.accept_embedded_rdf_xml} for those (a typical example is SVG). 
     - the file is HTML and there is a turtle portion in the C{<script>} element with type text/turtle. 
    
    @param node: a DOM node for the top level element
    @param graph: target rdf graph
    @type graph: RDFLib's Graph object instance
    @param state: the inherited state (namespaces, lang, etc)
    @type state: L{state.ExecutionContext}
    @return: whether an RDF/XML or turtle content has been detected or not. If TRUE, the RDFa processing should not occur on the node and its descendents. 
    @rtype: Boolean
    """
    #def _get_prefixes_in_turtle():
    #    retval = ""
    #    for key in state.term_or_curie.ns:
    #        retval += "@prefix %s: <%s> .\n" % (key, state.term_or_curie.ns[key])
    #    retval += '\n'
    #    return retval
    
    # This feature is optional!
    def _get_literal(Pnode):
        """
        Get the full text
        @param Pnode: DOM Node
        @return: string
        """
        rc = ""
        for node in Pnode.childNodes:
            if node.nodeType in [node.TEXT_NODE, node.CDATA_SECTION_NODE]:
                rc = rc + node.data
        # Sigh... the HTML5 parser does not recognize the CDATA escapes, ie, it just passes on the <![CDATA[ and ]]> strings:-(
        return rc.replace("<![CDATA[","").replace("]]>","")

    if state.options.embedded_rdf:
        # Embedded turtle, per the latest Turtle draft
        if state.options.host_language in accept_embedded_turtle and node.nodeName.lower() == "script":
            if node.hasAttribute("type") and node.getAttribute("type") == "text/turtle":
                #prefixes = _get_prefixes_in_turtle()
                #content  = _get_literal(node)
                #rdf = StringIO(prefixes + content)
                content  = _get_literal(node)
                rdf = StringIO(content)
                try:
                    graph.parse(rdf, format="n3", publicID = state.base)
                    state.options.add_info("The output graph includes triples coming from an embedded Turtle script")
                except:
                    _type, value, _traceback = sys.exc_info()
                    state.options.add_error("Embedded Turtle content could not be parsed (problems with %s?); ignored" % value)
            return True
        elif state.options.host_language in accept_embedded_rdf_xml and node.localName == "RDF" and node.namespaceURI == "http://www.w3.org/1999/02/22-rdf-syntax-ns#":
            rdf = StringIO(return_XML(state, node))
            try:
                graph.parse(rdf)
                state.options.add_info("The output graph includes triples coming from an embedded RDF/XML subtree")
            except:
                _type, value, _traceback = sys.exc_info()
                state.options.add_error("Embedded RDF/XML content could not parsed (problems with %s?); ignored" % value)
            return True
        else:
            return False
    else:
        return False