# Source code for rdflib.parser

    """
    Parser plugin interface.

    This module defines the parser plugin interface and contains other
    related parser support code.

    The module is mainly useful for those wanting to write a parser that
    can plugin to rdflib. If you are wanting to invoke a parser you likely
    want to do so through the Graph class parse method.

    """

    import os
    import sys
    from urllib.request import pathname2url, url2pathname
    from urllib.request import urlopen, Request
    from urllib.parse import urljoin
    from rdflib.py3compat import PY3
    if PY3:
        from io import BytesIO
        assert BytesIO
    else:
        from io import StringIO as BytesIO
    from xml.sax import xmlreader

    from rdflib import __version__
    from rdflib.term import URIRef
    from rdflib.namespace import Namespace

    __all__ = [
        'Parser', 'InputSource', 'StringInputSource',
        'URLInputSource', 'FileInputSource']

    class Parser(object):

        def __init__(self):
            pass

        def parse(self, source, sink):
            pass

    class InputSource(xmlreader.InputSource, object):
        """
        TODO:
        """

        def __init__(self, system_id=None):
            xmlreader.InputSource.__init__(self, system_id=system_id)
            self.content_type = None
            self.auto_close = False  # see Graph.parse(), true if opened by us

        def close(self):
            f = self.getByteStream()
            if f and hasattr(f, 'close'):
                f.close()

    class StringInputSource(InputSource):
        """
        TODO:
        """

        def __init__(self, value, system_id=None):
            super(StringInputSource, self).__init__(system_id)
            stream = BytesIO(value)
            self.setByteStream(stream)
            # TODO:
            #   encoding = value.encoding
            #   self.setEncoding(encoding)

    headers = {
        'User-agent':
        'rdflib-%s (http://rdflib.net/; eikeon@eikeon.com)' % __version__
    }

    class URLInputSource(InputSource):
        """
        TODO:
        """

        def __init__(self, system_id=None, format=None):
            super(URLInputSource, self).__init__(system_id)
            self.url = system_id

            # copy headers to change
            myheaders = dict(headers)
            if format == 'application/rdf+xml':
                myheaders['Accept'] = 'application/rdf+xml, */*;q=0.1'
            elif format == 'n3':
                myheaders['Accept'] = 'text/n3, */*;q=0.1'
            elif format == 'nt':
                myheaders['Accept'] = 'text/plain, */*;q=0.1'
            elif format == 'json-ld':
                myheaders['Accept'] = (
                    'application/ld+json, application/json;p=0.9, */*;q=0.1')
            else:
                myheaders['Accept'] = (
                    'application/rdf+xml,text/rdf+n3;q=0.9,' +
                    'application/xhtml+xml;q=0.5, */*;q=0.1')

            req = Request(system_id, None, myheaders)
            file = urlopen(req)
            # Fix for issue 130 https://github.com/RDFLib/rdflib/issues/130
            self.url = file.geturl()    # in case redirections took place
            self.setPublicId(self.url)
            self.content_type = file.info().get('content-type')
            if self.content_type is not None:
                self.content_type = self.content_type.split(";", 1)[0]
            self.setByteStream(file)
            # TODO: self.setEncoding(encoding)
            self.response_info = file.info() # a mimetools.Message instance

        def __repr__(self):
            return self.url

    class FileInputSource(InputSource):

        def __init__(self, file):
            base = urljoin("file:", pathname2url(os.getcwd()))
            system_id = URIRef(urljoin("file:", pathname2url(file.name)), base=base)
            super(FileInputSource, self).__init__(system_id)
            self.file = file
            self.setByteStream(file)
            # TODO: self.setEncoding(encoding)

        def __repr__(self):
            return repr(self.file)

    def create_input_source(source=None, publicID=None,
                            location=None, file=None, data=None, format=None):
        """
        Return an appropriate InputSource instance for the given
        parameters.
        """

        # test that exactly one of source, location, file, and data is not None.
        if sum((
            source is not None,
            location is not None,
            file is not None,
            data is not None,
        )) != 1:
            raise ValueError(
                'exactly one of source, location, file or data must be given'
            )

        input_source = None

        if source is not None:
            if isinstance(source, InputSource):
                input_source = source
            else:
                if isinstance(source, str):
                    location = source
                elif hasattr(source, "read") and not isinstance(source, Namespace):
                    f = source
                    input_source = InputSource()
                    input_source.setByteStream(f)
                    if f is sys.stdin:
                        input_source.setSystemId("file:///dev/stdin")
                    elif hasattr(f, "name"):
                        input_source.setSystemId(f.name)
                else:
                    raise Exception("Unexpected type '%s' for source '%s'" %
                                    (type(source), source))

        absolute_location = None  # Further to fix for issue 130

        auto_close = False  # make sure we close all file handles we open
        if location is not None:
            # Fix for Windows problem https://github.com/RDFLib/rdflib/issues/145
            if os.path.exists(location):
                location = pathname2url(location)
            base = urljoin("file:", "%s/" % pathname2url(os.getcwd()))
            absolute_location = URIRef(location, base=base).defrag()
            if absolute_location.startswith("file:///"):
                filename = url2pathname(absolute_location.replace("file:///", "/"))
                file = open(filename, "rb")
            else:
                input_source = URLInputSource(absolute_location, format)
            auto_close = True
            # publicID = publicID or absolute_location  # Further to fix
                                                        # for issue 130

        if file is not None:
            input_source = FileInputSource(file)

        if data is not None:
            if isinstance(data, str):
                data = data.encode('utf-8')
            input_source = StringInputSource(data)
            auto_close = True

        if input_source is None:
            raise Exception("could not create InputSource")
        else:
            input_source.auto_close |= auto_close
            if publicID is not None:  # Further to fix for issue 130
                input_source.setPublicId(publicID)
            # Further to fix for issue 130
            elif input_source.getPublicId() is None:
                input_source.setPublicId(absolute_location or "")
            return input_source