Merge branch 'master' into rwd
[wolnelektury.git] / apps / oai / handlers.py
1 from oaipmh import server, common, metadata, error
2 from catalogue.models import Book, Tag
3 from api.models import Deleted
4 from api.handlers import WL_BASE
5 from librarian.dcparser import BookInfo
6 from librarian import WLURI
7 from django.contrib.contenttypes.models import ContentType
8 from django.contrib.auth.models import User
9 from datetime import datetime
10 from lxml import etree
11 from lxml.etree import ElementTree
12 from django.db.models import Q
13 from django.conf import settings
14 from django.contrib.sites.models import Site
15 from django.utils import timezone
16
17
18 make_time_naive = lambda d: timezone.localtime(d).replace(tzinfo=None)
19
20 WL_DC_READER_XPATH = '(.|*)/rdf:RDF/rdf:Description/%s/text()' 
21 wl_dc_reader = metadata.MetadataReader(
22     fields={
23     'title':       ('textList', WL_DC_READER_XPATH % 'dc:title'),
24     'creator':     ('textList', WL_DC_READER_XPATH % 'dc:creator'),
25     'subject':     ('textList', (WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH) %
26                     ('dc:subject.period', 'dc:subject.type', 'dc:subject.genre')),
27     'description': ('textList', WL_DC_READER_XPATH % 'dc:description'),
28     'publisher':   ('textList', WL_DC_READER_XPATH % 'dc:publisher'),
29     'contributor': ('textList', (WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH + ' | ' + WL_DC_READER_XPATH) %
30                     ('dc:contributor.editor', 'dc:contributor.translator', 'dc:contributor.technical_editor')),
31     'date':        ('textList', WL_DC_READER_XPATH % 'dc:date'),
32     'type':        ('textList', WL_DC_READER_XPATH % 'dc:type'),
33     'format':      ('textList', WL_DC_READER_XPATH % 'dc:format'),
34     'identifier':  ('textList', WL_DC_READER_XPATH % 'dc:identifier.url'),
35     'source':      ('textList', WL_DC_READER_XPATH % 'dc:source'),
36     'language':    ('textList', WL_DC_READER_XPATH % 'dc:language'),
37     #'isPartOf':     ('textList', 'rdf:RDF/rdf:Description/dc:relation.isPartOf/text()'),
38     'hasPart':     ('textList', WL_DC_READER_XPATH % 'dc:relation.hasPart'),
39     #    'relation':    ('textList', 'rdf:RDF/rdf:Description/dc:relation/text()'),
40     #    'coverage':    ('textList', 'rdf:RDF/rdf:Description/dc:coverage/text()'),
41     'rights':      ('textList', WL_DC_READER_XPATH % 'dc:rights')
42     },
43     namespaces={
44     'dc': 'http://purl.org/dc/elements/1.1/',
45     'rdf': 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'}
46     )
47
48
49 NS_DCTERMS = "http://purl.org/dc/terms/"
50
51
52 def nsdcterms(name):
53     return '{%s}%s' % (NS_DCTERMS, name)
54
55
56 class Catalogue(common.ResumptionOAIPMH):
57     TAG_CATEGORIES = ['author', 'epoch', 'kind', 'genre']
58
59     def __init__(self, metadata_registry):
60         super(Catalogue, self).__init__()
61         self.metadata_registry = metadata_registry
62
63         self.oai_id = "oai:" + Site.objects.get_current().domain + ":%s"
64
65         # earliest change
66         year_zero = timezone.make_aware(datetime(1990, 1, 1, 0, 0, 0), timezone.utc)
67
68         try:
69             earliest_change = \
70                 Book.objects.order_by('changed_at')[0].changed_at
71         except: earliest_change = year_zero
72
73         try:
74             earliest_delete = \
75                 Deleted.objects.exclude(slug__exact=u'').ordery_by('deleted_at')[0].deleted_at
76         except: earliest_delete = year_zero
77
78         self.earliest_datestamp = earliest_change <= earliest_delete and \
79             earliest_change or earliest_delete
80
81     def metadata(self, book):
82         try:
83             xml = etree.parse(book.xml_file)
84         finally:
85             book.xml_file.close()
86         md = wl_dc_reader(xml)
87         m = md.getMap()
88         if book.parent:
89             m['isPartOf'] = [str(WLURI.from_slug(book.parent.slug))]
90         return m
91
92     def record_for_book(self, book, headers_only=False):
93         meta = None
94         identifier = self.slug_to_identifier(book.slug)
95         if isinstance(book, Book):
96             #            setSpec = map(self.tag_to_setspec, book.tags.filter(category__in=self.TAG_CATEGORIES))
97             header = common.Header(identifier, make_time_naive(book.changed_at), [], False)
98             if not headers_only:
99                 meta = common.Metadata(self.metadata(book))
100             about = None
101         elif isinstance(book, Deleted):
102             header = common.Header(identifier, make_time_naive(book.deleted_at), [], True)
103             if not headers_only:
104                 meta = common.Metadata({})
105             about = None
106         if headers_only:
107             return header
108         return header, meta, about
109
110     def identify(self, **kw):
111         ident = common.Identify(
112             'Wolne Lektury',  # generate
113             '%s/oaipmh' % WL_BASE,  # generate
114             '2.0',  # version
115             [m[1] for m in settings.MANAGERS],  # adminEmails
116             make_time_naive(self.earliest_datestamp),  # earliest datestamp of any change
117             'persistent',  # deletedRecord
118             'YYYY-MM-DDThh:mm:ssZ',  # granularity
119             ['identity'],  # compression
120             []  # descriptions
121             )
122         return ident
123
124     def books(self, tag, from_, until):
125         if tag:
126             # we do not support sets, since they are problematic for deleted books.
127             raise error.NoSetHierarchyError("Wolne Lektury does not support sets.")
128             # books = Book.tagged.with_all([tag])
129         else:
130             books = Book.objects.all()
131         deleted = Deleted.objects.exclude(slug__exact=u'')
132
133         books = books.order_by('changed_at')
134         deleted = deleted.order_by('deleted_at')
135         if from_:
136             books = books.filter(changed_at__gte=from_)
137             deleted = deleted.filter(deleted_at__gte=from_)
138         if until:
139             books = books.filter(changed_at__lte=until)
140             deleted = deleted.filter(deleted_at__lte=until)
141         return list(books) + list(deleted)
142
143     @staticmethod
144     def tag_to_setspec(tag):
145         return "%s:%s" % (tag.category, tag.slug)
146
147     @staticmethod
148     def setspec_to_tag(s):
149         if not s: return None
150         cs = s.split(':')
151         if len(cs) == 2:
152             if not cs[0] in Catalogue.TAG_CATEGORIES:
153                 raise error.NoSetHierarchyError("No category part in set")
154             tag = Tag.objects.get(slug=cs[1], category=cs[0])
155             return tag
156         raise error.NoSetHierarchyError("Setspec should have two components: category:slug")
157
158     def getRecord(self, **kw):
159         """
160 Returns (header, metadata, about) for given record.
161         """
162         slug = self.identifier_to_slug(kw['identifier'])
163         try:
164             book = Book.objects.get(slug=slug)
165             return self.record_for_book(book)
166         except Book.DoesNotExist:
167             book_type = ContentType.objects.get_for_model(Book)
168             try:
169                 deleted_book = Deleted.objects.get(content_type=book_type,
170                                                   slug=slug)
171             except:
172                 raise error.IdDoesNotExistError("No item for this identifier")
173             return self.record_for_book(deleted_book)
174
175     def validate_kw(self, kw):
176         if 'resumptionToken' in kw:
177             raise error.BadResumptionTokenError("No resumption token support at this point")
178         if 'metadataPrefix' in kw and not self.metadata_registry.hasWriter(kw['metadataPrefix']):
179             raise error.CannotDisseminateFormatError("This format is not supported")
180
181     def identifier_to_slug(self, ident):
182         return ident.split(':')[-1]
183
184     def slug_to_identifier(self, slug):
185         return self.oai_id % slug
186
187     def listIdentifiers(self, **kw):
188         self.validate_kw(kw)
189         records = [self.record_for_book(book, headers_only=True) for
190                    book in self.books(None,
191                            kw.get('from_', None),
192                            kw.get('until', None))]
193         return records, None
194
195     def listRecords(self, **kw):
196         """
197 can get a resumptionToken kw.
198 returns result, token
199         """
200         self.validate_kw(kw)
201         records = [self.record_for_book(book) for
202                    book in self.books(None,
203                            kw.get('from_', None),
204                            kw.get('until', None))]
205
206         return records, None
207
208     def listMetadataFormats(self, **kw):
209         formats = [
210             ('oai_dc',
211              'http://www.openarchives.org/OAI/2.0/oai_dc.xsd',
212              server.NS_OAIDC),
213             ('qdc',
214              'http://dublincore.org/schemas/xmls/qdc/2006/01/06/dcterms.xsd',
215              NS_DCTERMS)]
216         if 'identifier' in kw:
217             slug = self.identifier_to_slug(kw['identifier'])
218             try:
219                 b = Book.objects.get(slug=slug)
220                 return formats
221             except:
222                 try:
223                     d = Deleted.objects.get(slug=slug)
224                     return []
225                 except:
226                     raise error.IdDoesNotExistError("This id does not exist")
227         else:
228             return formats
229
230     def listSets(self, **kw):
231         raise error.NoSetHierarchyError("Wolne Lektury does not support sets.")
232         # tags = []
233         # for category in Catalogue.TAG_CATEGORIES:
234         #     for tag in Tag.objects.filter(category=category):
235         #         tags.append(("%s:%s" % (tag.category, tag.slug),
236         #                      tag.name,
237         #                      tag.description))
238         # return tags, None