lakesuperior_legacy/lakesuperior/model/ldp_nr.py

import logging
import pdb

from rdflib import Graph
from rdflib.namespace import RDF, XSD
from rdflib.resource import Resource
from rdflib.term import URIRef, Literal, Variable

from lakesuperior.env import env
from lakesuperior.dictionaries.namespaces import ns_collection as nsc
from lakesuperior.model.ldpr import Ldpr
from lakesuperior.model.ldp_rs import LdpRs


nonrdfly = env.app_globals.nonrdfly
logger = logging.getLogger(__name__)


class LdpNr(Ldpr):
    '''LDP-NR (Non-RDF Source).

    Definition: https://www.w3.org/TR/ldp/#ldpnr
    '''

    base_types = {
        nsc['fcrepo'].Binary,
        nsc['fcrepo'].Resource,
        nsc['ldp'].Resource,
        nsc['ldp'].NonRDFSource,
    }

    def __init__(self, uuid, stream=None, mimetype=None,
            disposition=None, **kwargs):
        '''
        Extends Ldpr.__init__ by adding LDP-NR specific parameters.
        '''
        super().__init__(uuid, **kwargs)

        self._imr_options = {}
        if stream:
            self.workflow = self.WRKF_INBOUND
            self.stream = stream
        else:
            self.workflow = self.WRKF_OUTBOUND

        if not mimetype:
            self.mimetype = (
                    self.metadata.value(nsc['ebucore'].hasMimeType)
                    if self.is_stored
                    else 'application/octet-stream')
        else:
            self.mimetype = mimetype

        self.disposition = disposition


    @property
    def filename(self):
        return self.imr.value(nsc['ebucore'].filename)


    @property
    def local_path(self):
        cksum_term = self.imr.value(nsc['premis'].hasMessageDigest)
        cksum = str(cksum_term.identifier.replace('urn:sha1:',''))
        return nonrdfly.local_path(cksum)


    def create_or_replace_rsrc(self, create_only=False):
        '''
        Create a new binary resource with a corresponding RDF representation.

        @param file (Stream) A Stream resource representing the uploaded file.
        '''
        # Persist the stream.
        self.digest, self.size = nonrdfly.persist(self.stream)

        # Try to persist metadata. If it fails, delete the file.
        logger.debug('Persisting LDP-NR triples in {}'.format(self.uri))
        try:
            ev_type = super().create_or_replace_rsrc(create_only)
        except:
            # self.digest is also the file UID.
            nonrdfly.delete(self.digest)
            raise
        else:
            return ev_type


    def patch_metadata(self, update_str):
        '''
        Update resource metadata by applying a SPARQL-UPDATE query.

        @param update_str (string) SPARQL-Update staements.
        '''
        self.handling = 'lenient' # FCREPO does that and Hyrax requires it.

        return self._sparql_update(update_str)


    ## PROTECTED METHODS ##

    def _add_srv_mgd_triples(self, create=False):
        '''
        Add all metadata for the RDF representation of the LDP-NR.

        @param stream (BufferedIO) The uploaded data stream.
        @param mimetype (string) MIME type of the uploaded file.
        @param disposition (defaultdict) The `Content-Disposition` header
        content, parsed through `parse_rfc7240`.
        '''
        super()._add_srv_mgd_triples(create)

        # File size.
        logger.debug('Data stream size: {}'.format(self.size))
        self.provided_imr.set(nsc['premis'].hasSize, Literal(self.size))

        # Checksum.
        cksum_term = URIRef('urn:sha1:{}'.format(self.digest))
        self.provided_imr.set(nsc['premis'].hasMessageDigest, cksum_term)

        # MIME type.
        self.provided_imr.set(nsc['ebucore']['hasMimeType'], 
                Literal(self.mimetype))

        # File name.
        logger.debug('Disposition: {}'.format(self.disposition))
        try:
            self.provided_imr.set(nsc['ebucore']['filename'], Literal(
                    self.disposition['attachment']['parameters']['filename']))
        except (KeyError, TypeError) as e:
            pass