088d0eee642a32cd382a9410a9d90238057b3ce7
[wolnelektury.git] / apps / catalogue / views.py
1 # -*- coding: utf-8 -*-
2 # This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
3 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
4 #
5 import tempfile
6 import zipfile
7 import sys
8 import pprint
9 import traceback
10 import re
11 import itertools
12 from operator import itemgetter
13
14 from django.conf import settings
15 from django.template import RequestContext
16 from django.shortcuts import render_to_response, get_object_or_404
17 from django.http import HttpResponse, HttpResponseRedirect, Http404
18 from django.core.urlresolvers import reverse
19 from django.db.models import Q
20 from django.contrib.auth.decorators import login_required, user_passes_test
21 from django.utils.datastructures import SortedDict
22 from django.views.decorators.http import require_POST
23 from django.contrib import auth
24 from django.contrib.auth.forms import UserCreationForm, AuthenticationForm
25 from django.utils import simplejson
26 from django.utils.functional import Promise
27 from django.utils.encoding import force_unicode
28 from django.utils.http import urlquote_plus
29 from django.views.decorators import cache
30 from django.utils.translation import ugettext as _
31 from django.views.generic.list_detail import object_list
32
33 from catalogue import models
34 from catalogue import forms
35 from catalogue.utils import split_tags
36 from newtagging import views as newtagging_views
37
38
39 staff_required = user_passes_test(lambda user: user.is_staff)
40
41
42 class LazyEncoder(simplejson.JSONEncoder):
43     def default(self, obj):
44         if isinstance(obj, Promise):
45             return force_unicode(obj)
46         return obj
47
48 # shortcut for JSON reponses
49 class JSONResponse(HttpResponse):
50     def __init__(self, data={}, callback=None, **kwargs):
51         # get rid of mimetype
52         kwargs.pop('mimetype', None)
53         data = simplejson.dumps(data)
54         if callback:
55             data = callback + "(" + data + ");" 
56         super(JSONResponse, self).__init__(data, mimetype="application/json", **kwargs)
57
58
59 def main_page(request):
60     if request.user.is_authenticated():
61         shelves = models.Tag.objects.filter(category='set', user=request.user)
62         new_set_form = forms.NewSetForm()
63
64     tags = models.Tag.objects.exclude(category__in=('set', 'book'))
65     for tag in tags:
66         tag.count = tag.get_count()
67     categories = split_tags(tags)
68     fragment_tags = categories.get('theme', [])
69
70     form = forms.SearchForm()
71     return render_to_response('catalogue/main_page.html', locals(),
72         context_instance=RequestContext(request))
73
74
75 def book_list(request):
76     form = forms.SearchForm()
77
78     books_by_parent = {}
79     for book in models.Book.objects.all().order_by('parent_number'):
80         books_by_parent.setdefault(book.parent, []).append(book)
81
82     orphans = []
83     books_by_author = SortedDict()
84     books_nav = SortedDict()
85     for tag in models.Tag.objects.filter(category='author'):
86         books_by_author[tag] = []
87         if books_nav.has_key(tag.sort_key[0]):
88             books_nav[tag.sort_key[0]].append(tag)
89         else:
90             books_nav[tag.sort_key[0]] = [tag]
91
92     for book in books_by_parent[None]:
93         authors = list(book.tags.filter(category='author'))
94         if authors:
95             for author in authors:
96                 books_by_author[author].append(book)
97         else:
98             orphans.append(book)
99
100     return render_to_response('catalogue/book_list.html', locals(),
101         context_instance=RequestContext(request))
102
103
104 def differentiate_tags(request, tags, ambiguous_slugs):
105     beginning = '/'.join(tag.url_chunk for tag in tags)
106     unparsed = '/'.join(ambiguous_slugs[1:])
107     options = []
108     for tag in models.Tag.objects.exclude(category='book').filter(slug=ambiguous_slugs[0]):
109         options.append({
110             'url_args': '/'.join((beginning, tag.url_chunk, unparsed)).strip('/'),
111             'tags': [tag]
112         })
113     return render_to_response('catalogue/differentiate_tags.html',
114                 {'tags': tags, 'options': options, 'unparsed': ambiguous_slugs[1:]},
115                 context_instance=RequestContext(request))
116
117
118 def tagged_object_list(request, tags=''):
119     try:
120         tags = models.Tag.get_tag_list(tags)
121     except models.Tag.DoesNotExist:
122         raise Http404
123     except models.Tag.MultipleObjectsReturned, e:
124         return differentiate_tags(request, e.tags, e.ambiguous_slugs)
125
126     try:
127         if len(tags) > settings.MAX_TAG_LIST:
128             raise Http404
129     except AttributeError:
130         pass
131
132     if len([tag for tag in tags if tag.category == 'book']):
133         raise Http404
134
135     theme_is_set = [tag for tag in tags if tag.category == 'theme']
136     shelf_is_set = [tag for tag in tags if tag.category == 'set']
137     only_shelf = shelf_is_set and len(tags) == 1
138     only_my_shelf = only_shelf and request.user.is_authenticated() and request.user == tags[0].user
139
140     objects = only_author = pd_counter = None
141     categories = {}
142
143     if theme_is_set:
144         shelf_tags = [tag for tag in tags if tag.category == 'set']
145         fragment_tags = [tag for tag in tags if tag.category != 'set']
146         fragments = models.Fragment.tagged.with_all(fragment_tags)
147
148         if shelf_tags:
149             books = models.Book.tagged.with_all(shelf_tags).order_by()
150             l_tags = models.Tag.objects.filter(category='book', slug__in=[book.book_tag_slug() for book in books])
151             fragments = models.Fragment.tagged.with_any(l_tags, fragments)
152
153         # newtagging goes crazy if we just try:
154         #related_tags = models.Tag.objects.usage_for_queryset(fragments, counts=True,
155         #                    extra={'where': ["catalogue_tag.category != 'book'"]})
156         fragment_keys = [fragment.pk for fragment in fragments]
157         if fragment_keys:
158             related_tags = models.Fragment.tags.usage(counts=True,
159                                 filters={'pk__in': fragment_keys},
160                                 extra={'where': ["catalogue_tag.category != 'book'"]})
161             related_tags = (tag for tag in related_tags if tag not in fragment_tags)
162             categories = split_tags(related_tags)
163
164             objects = fragments
165     else:
166         # get relevant books and their tags
167         objects = models.Book.tagged.with_all(tags).order_by()
168         if not shelf_is_set:
169             # eliminate descendants
170             l_tags = models.Tag.objects.filter(category='book', slug__in=[book.book_tag_slug() for book in objects])
171             descendants_keys = [book.pk for book in models.Book.tagged.with_any(l_tags)]
172             if descendants_keys:
173                 objects = objects.exclude(pk__in=descendants_keys)
174
175         # get related tags from `tag_counter` and `theme_counter`
176         related_counts = {}
177         tags_pks = [tag.pk for tag in tags]
178         for book in objects:
179             for tag_pk, value in itertools.chain(book.tag_counter.iteritems(), book.theme_counter.iteritems()):
180                 if tag_pk in tags_pks:
181                     continue
182                 related_counts[tag_pk] = related_counts.get(tag_pk, 0) + value
183         related_tags = models.Tag.objects.filter(pk__in=related_counts.keys())
184         related_tags = [tag for tag in related_tags if tag not in tags]
185         for tag in related_tags:
186             tag.count = related_counts[tag.pk]
187
188         categories = split_tags(related_tags)
189         del related_tags
190
191     if not objects:
192         only_author = len(tags) == 1 and tags[0].category == 'author'
193         pd_counter = only_author and tags[0].goes_to_pd()
194         objects = models.Book.objects.none()
195
196     return object_list(
197         request,
198         objects,
199         template_name='catalogue/tagged_object_list.html',
200         extra_context={
201             'categories': categories,
202             'only_shelf': only_shelf,
203             'only_author': only_author,
204             'pd_counter': pd_counter,
205             'only_my_shelf': only_my_shelf,
206             'formats_form': forms.DownloadFormatsForm(),
207
208             'tags': tags,
209         }
210     )
211
212
213 def book_fragments(request, book_slug, theme_slug):
214     book = get_object_or_404(models.Book, slug=book_slug)
215     book_tag = get_object_or_404(models.Tag, slug='l-' + book_slug, category='book')
216     theme = get_object_or_404(models.Tag, slug=theme_slug, category='theme')
217     fragments = models.Fragment.tagged.with_all([book_tag, theme])
218
219     form = forms.SearchForm()
220     return render_to_response('catalogue/book_fragments.html', locals(),
221         context_instance=RequestContext(request))
222
223
224 def book_detail(request, slug):
225     try:
226         book = models.Book.objects.get(slug=slug)
227     except models.Book.DoesNotExist:
228         return book_stub_detail(request, slug)
229
230     book_tag = book.book_tag()
231     tags = list(book.tags.filter(~Q(category='set')))
232     categories = split_tags(tags)
233     book_children = book.children.all().order_by('parent_number')
234     
235     _book = book
236     parents = []
237     while _book.parent:
238         parents.append(_book.parent)
239         _book = _book.parent
240     parents = reversed(parents)
241
242     theme_counter = book.theme_counter
243     book_themes = models.Tag.objects.filter(pk__in=theme_counter.keys())
244     for tag in book_themes:
245         tag.count = theme_counter[tag.pk]
246
247     extra_info = book.get_extra_info_value()
248
249     form = forms.SearchForm()
250     return render_to_response('catalogue/book_detail.html', locals(),
251         context_instance=RequestContext(request))
252
253
254 def book_stub_detail(request, slug):
255     book = get_object_or_404(models.BookStub, slug=slug)
256     pd_counter = book.pd
257     form = forms.SearchForm()
258
259     return render_to_response('catalogue/book_stub_detail.html', locals(),
260         context_instance=RequestContext(request))
261
262
263 def book_text(request, slug):
264     book = get_object_or_404(models.Book, slug=slug)
265     if not book.has_html_file():
266         raise Http404
267     book_themes = {}
268     for fragment in book.fragments.all():
269         for theme in fragment.tags.filter(category='theme'):
270             book_themes.setdefault(theme, []).append(fragment)
271
272     book_themes = book_themes.items()
273     book_themes.sort(key=lambda s: s[0].sort_key)
274     return render_to_response('catalogue/book_text.html', locals(),
275         context_instance=RequestContext(request))
276
277
278 # ==========
279 # = Search =
280 # ==========
281
282 def _no_diacritics_regexp(query):
283     """ returns a regexp for searching for a query without diacritics
284
285     should be locale-aware """
286     names = {
287         u'a':u'aąĄ', u'c':u'cćĆ', u'e':u'eęĘ', u'l': u'lłŁ', u'n':u'nńŃ', u'o':u'oóÓ', u's':u'sśŚ', u'z':u'zźżŹŻ',
288         u'ą':u'ąĄ', u'ć':u'ćĆ', u'ę':u'ęĘ', u'ł': u'łŁ', u'ń':u'ńŃ', u'ó':u'óÓ', u'ś':u'śŚ', u'ź':u'źŹ', u'ż':u'żŻ'
289         }
290     def repl(m):
291         l = m.group()
292         return u"(%s)" % '|'.join(names[l])
293     return re.sub(u'[%s]' % (u''.join(names.keys())), repl, query)
294
295 def unicode_re_escape(query):
296     """ Unicode-friendly version of re.escape """
297     return re.sub('(?u)(\W)', r'\\\1', query)
298
299 def _word_starts_with(name, prefix):
300     """returns a Q object getting models having `name` contain a word
301     starting with `prefix`
302
303     We define word characters as alphanumeric and underscore, like in JS.
304
305     Works for MySQL, PostgreSQL, Oracle.
306     For SQLite, _sqlite* version is substituted for this.
307     """
308     kwargs = {}
309
310     prefix = _no_diacritics_regexp(unicode_re_escape(prefix))
311     # can't use [[:<:]] (word start),
312     # but we want both `xy` and `(xy` to catch `(xyz)`
313     kwargs['%s__iregex' % name] = u"(^|[^[:alnum:]_])%s" % prefix
314
315     return Q(**kwargs)
316
317
318 def _sqlite_word_starts_with(name, prefix):
319     """ version of _word_starts_with for SQLite
320
321     SQLite in Django uses Python re module
322     """
323     kwargs = {}
324     prefix = _no_diacritics_regexp(unicode_re_escape(prefix))
325     kwargs['%s__iregex' % name] = ur"(^|(?<=[^\wąćęłńóśźżĄĆĘŁŃÓŚŹŻ]))%s" % prefix
326     return Q(**kwargs)
327
328
329 if settings.DATABASE_ENGINE == 'sqlite3':
330     _word_starts_with = _sqlite_word_starts_with
331
332
333 def _tags_starting_with(prefix, user=None):
334     prefix = prefix.lower()
335     book_stubs = models.BookStub.objects.filter(_word_starts_with('title', prefix))
336     books = models.Book.objects.filter(_word_starts_with('title', prefix))
337     book_stubs = filter(lambda x: x not in books, book_stubs)
338     tags = models.Tag.objects.filter(_word_starts_with('name', prefix))
339     if user and user.is_authenticated():
340         tags = tags.filter(~Q(category='book') & (~Q(category='set') | Q(user=user)))
341     else:
342         tags = tags.filter(~Q(category='book') & ~Q(category='set'))
343     return list(books) + list(tags) + list(book_stubs)
344
345
346 def _get_result_link(match, tag_list):
347     if isinstance(match, models.Book) or isinstance(match, models.BookStub):
348         return match.get_absolute_url()
349     else:
350         return reverse('catalogue.views.tagged_object_list',
351             kwargs={'tags': '/'.join(tag.url_chunk for tag in tag_list + [match])}
352         )
353
354 def _get_result_type(match):
355     if isinstance(match, models.Book) or isinstance(match, models.BookStub):
356         type = 'book'
357     else:
358         type = match.category
359     return type
360
361
362
363 def find_best_matches(query, user=None):
364     """ Finds a Book, Tag or Bookstub best matching a query.
365
366     Returns a with:
367       - zero elements when nothing is found,
368       - one element when a best result is found,
369       - more then one element on multiple exact matches
370
371     Raises a ValueError on too short a query.
372     """
373
374     query = query.lower()
375     if len(query) < 2:
376         raise ValueError("query must have at least two characters")
377
378     result = tuple(_tags_starting_with(query, user))
379     exact_matches = tuple(res for res in result if res.name.lower() == query)
380     if exact_matches:
381         return exact_matches
382     else:
383         return result[:1]
384
385
386 def search(request):
387     tags = request.GET.get('tags', '')
388     prefix = request.GET.get('q', '')
389
390     try:
391         tag_list = models.Tag.get_tag_list(tags)
392     except:
393         tag_list = []
394
395     try:
396         result = find_best_matches(prefix, request.user)
397     except ValueError:
398         return render_to_response('catalogue/search_too_short.html', {'tags':tag_list, 'prefix':prefix},
399             context_instance=RequestContext(request))
400
401     if len(result) == 1:
402         return HttpResponseRedirect(_get_result_link(result[0], tag_list))
403     elif len(result) > 1:
404         return render_to_response('catalogue/search_multiple_hits.html',
405             {'tags':tag_list, 'prefix':prefix, 'results':((x, _get_result_link(x, tag_list), _get_result_type(x)) for x in result)},
406             context_instance=RequestContext(request))
407     else:
408         return render_to_response('catalogue/search_no_hits.html', {'tags':tag_list, 'prefix':prefix},
409             context_instance=RequestContext(request))
410
411
412 def tags_starting_with(request):
413     prefix = request.GET.get('q', '')
414     # Prefix must have at least 2 characters
415     if len(prefix) < 2:
416         return HttpResponse('')
417     tags_list = []
418     result = ""   
419     for tag in _tags_starting_with(prefix, request.user):
420         if not tag.name in tags_list:
421             result += "\n" + tag.name
422             tags_list.append(tag.name)
423     return HttpResponse(result)
424
425 def json_tags_starting_with(request, callback=None):
426     # Callback for JSONP
427     prefix = request.GET.get('q', '')
428     callback = request.GET.get('callback', '')
429     # Prefix must have at least 2 characters
430     if len(prefix) < 2:
431         return HttpResponse('')
432     tags_list = []
433     result = ""   
434     for tag in _tags_starting_with(prefix, request.user):
435         if not tag.name in tags_list:
436             result += "\n" + tag.name
437             tags_list.append(tag.name)
438     dict_result = {"matches": tags_list}
439     return JSONResponse(dict_result, callback)
440
441 # ====================
442 # = Shelf management =
443 # ====================
444 @login_required
445 @cache.never_cache
446 def user_shelves(request):
447     shelves = models.Tag.objects.filter(category='set', user=request.user)
448     new_set_form = forms.NewSetForm()
449     return render_to_response('catalogue/user_shelves.html', locals(),
450             context_instance=RequestContext(request))
451
452 @cache.never_cache
453 def book_sets(request, slug):
454     book = get_object_or_404(models.Book, slug=slug)
455     user_sets = models.Tag.objects.filter(category='set', user=request.user)
456     book_sets = book.tags.filter(category='set', user=request.user)
457
458     if not request.user.is_authenticated():
459         return HttpResponse(_('<p>To maintain your shelves you need to be logged in.</p>'))
460
461     if request.method == 'POST':
462         form = forms.ObjectSetsForm(book, request.user, request.POST)
463         if form.is_valid():
464             old_shelves = list(book.tags.filter(category='set'))
465             new_shelves = [models.Tag.objects.get(pk=id) for id in form.cleaned_data['set_ids']]
466
467             for shelf in [shelf for shelf in old_shelves if shelf not in new_shelves]:
468                 shelf.book_count = None
469                 shelf.save()
470
471             for shelf in [shelf for shelf in new_shelves if shelf not in old_shelves]:
472                 shelf.book_count = None
473                 shelf.save()
474
475             book.tags = new_shelves + list(book.tags.filter(~Q(category='set') | ~Q(user=request.user)))
476             if request.is_ajax():
477                 return HttpResponse(_('<p>Shelves were sucessfully saved.</p>'))
478             else:
479                 return HttpResponseRedirect('/')
480     else:
481         form = forms.ObjectSetsForm(book, request.user)
482         new_set_form = forms.NewSetForm()
483
484     return render_to_response('catalogue/book_sets.html', locals(),
485         context_instance=RequestContext(request))
486
487
488 @login_required
489 @require_POST
490 @cache.never_cache
491 def remove_from_shelf(request, shelf, book):
492     book = get_object_or_404(models.Book, slug=book)
493     shelf = get_object_or_404(models.Tag, slug=shelf, category='set', user=request.user)
494
495     if shelf in book.tags:
496         models.Tag.objects.remove_tag(book, shelf)
497
498         shelf.book_count = None
499         shelf.save()
500
501         return HttpResponse(_('Book was successfully removed from the shelf'))
502     else:
503         return HttpResponse(_('This book is not on the shelf'))
504
505
506 def collect_books(books):
507     """
508     Returns all real books in collection.
509     """
510     result = []
511     for book in books:
512         if len(book.children.all()) == 0:
513             result.append(book)
514         else:
515             result += collect_books(book.children.all())
516     return result
517
518
519 @cache.never_cache
520 def download_shelf(request, slug):
521     """"
522     Create a ZIP archive on disk and transmit it in chunks of 8KB,
523     without loading the whole file into memory. A similar approach can
524     be used for large dynamic PDF files.
525     """
526     shelf = get_object_or_404(models.Tag, slug=slug, category='set')
527
528     formats = []
529     form = forms.DownloadFormatsForm(request.GET)
530     if form.is_valid():
531         formats = form.cleaned_data['formats']
532     if len(formats) == 0:
533         formats = ['pdf', 'epub', 'odt', 'txt', 'mp3', 'ogg']
534
535     # Create a ZIP archive
536     temp = tempfile.TemporaryFile()
537     archive = zipfile.ZipFile(temp, 'w')
538
539     already = set()
540     for book in collect_books(models.Book.tagged.with_all(shelf)):
541         if 'pdf' in formats and book.pdf_file:
542             filename = book.pdf_file.path
543             archive.write(filename, str('%s.pdf' % book.slug))
544         if book.root_ancestor not in already and 'epub' in formats and book.root_ancestor.epub_file:
545             filename = book.root_ancestor.epub_file.path
546             archive.write(filename, str('%s.epub' % book.root_ancestor.slug))
547             already.add(book.root_ancestor)
548         if 'odt' in formats and book.odt_file:
549             filename = book.odt_file.path
550             archive.write(filename, str('%s.odt' % book.slug))
551         if 'txt' in formats and book.txt_file:
552             filename = book.txt_file.path
553             archive.write(filename, str('%s.txt' % book.slug))
554         if 'mp3' in formats and book.mp3_file:
555             filename = book.mp3_file.path
556             archive.write(filename, str('%s.mp3' % book.slug))
557         if 'ogg' in formats and book.ogg_file:
558             filename = book.ogg_file.path
559             archive.write(filename, str('%s.ogg' % book.slug))
560     archive.close()
561
562     response = HttpResponse(content_type='application/zip', mimetype='application/x-zip-compressed')
563     response['Content-Disposition'] = 'attachment; filename=%s.zip' % shelf.sort_key
564     response['Content-Length'] = temp.tell()
565
566     temp.seek(0)
567     response.write(temp.read())
568     return response
569
570
571 @cache.never_cache
572 def shelf_book_formats(request, shelf):
573     """"
574     Returns a list of formats of books in shelf.
575     """
576     shelf = get_object_or_404(models.Tag, slug=shelf, category='set')
577
578     formats = {'pdf': False, 'epub': False, 'odt': False, 'txt': False, 'mp3': False, 'ogg': False}
579
580     for book in collect_books(models.Book.tagged.with_all(shelf)):
581         if book.pdf_file:
582             formats['pdf'] = True
583         if book.root_ancestor.epub_file:
584             formats['epub'] = True
585         if book.odt_file:
586             formats['odt'] = True
587         if book.txt_file:
588             formats['txt'] = True
589         if book.mp3_file:
590             formats['mp3'] = True
591         if book.ogg_file:
592             formats['ogg'] = True
593
594     return HttpResponse(LazyEncoder().encode(formats))
595
596
597 @login_required
598 @require_POST
599 @cache.never_cache
600 def new_set(request):
601     new_set_form = forms.NewSetForm(request.POST)
602     if new_set_form.is_valid():
603         new_set = new_set_form.save(request.user)
604
605         if request.is_ajax():
606             return HttpResponse(_('<p>Shelf <strong>%s</strong> was successfully created</p>') % new_set)
607         else:
608             return HttpResponseRedirect('/')
609
610     return HttpResponseRedirect('/')
611
612
613 @login_required
614 @require_POST
615 @cache.never_cache
616 def delete_shelf(request, slug):
617     user_set = get_object_or_404(models.Tag, slug=slug, category='set', user=request.user)
618     user_set.delete()
619
620     if request.is_ajax():
621         return HttpResponse(_('<p>Shelf <strong>%s</strong> was successfully removed</p>') % user_set.name)
622     else:
623         return HttpResponseRedirect('/')
624
625
626 # ==================
627 # = Authentication =
628 # ==================
629 @require_POST
630 @cache.never_cache
631 def login(request):
632     form = AuthenticationForm(data=request.POST, prefix='login')
633     if form.is_valid():
634         auth.login(request, form.get_user())
635         response_data = {'success': True, 'errors': {}}
636     else:
637         response_data = {'success': False, 'errors': form.errors}
638     return HttpResponse(LazyEncoder(ensure_ascii=False).encode(response_data))
639
640
641 @require_POST
642 @cache.never_cache
643 def register(request):
644     registration_form = UserCreationForm(request.POST, prefix='registration')
645     if registration_form.is_valid():
646         user = registration_form.save()
647         user = auth.authenticate(
648             username=registration_form.cleaned_data['username'],
649             password=registration_form.cleaned_data['password1']
650         )
651         auth.login(request, user)
652         response_data = {'success': True, 'errors': {}}
653     else:
654         response_data = {'success': False, 'errors': registration_form.errors}
655     return HttpResponse(LazyEncoder(ensure_ascii=False).encode(response_data))
656
657
658 @cache.never_cache
659 def logout_then_redirect(request):
660     auth.logout(request)
661     return HttpResponseRedirect(urlquote_plus(request.GET.get('next', '/'), safe='/?='))
662
663
664
665 # =========
666 # = Admin =
667 # =========
668 @login_required
669 @staff_required
670 def import_book(request):
671     """docstring for import_book"""
672     book_import_form = forms.BookImportForm(request.POST, request.FILES)
673     if book_import_form.is_valid():
674         try:
675             book_import_form.save()
676         except:
677             info = sys.exc_info()
678             exception = pprint.pformat(info[1])
679             tb = '\n'.join(traceback.format_tb(info[2]))
680             return HttpResponse(_("An error occurred: %(exception)s\n\n%(tb)s") % {'exception':exception, 'tb':tb}, mimetype='text/plain')
681         return HttpResponse(_("Book imported successfully"))
682     else:
683         return HttpResponse(_("Error importing file: %r") % book_import_form.errors)
684
685
686
687 def clock(request):
688     """ Provides server time for jquery.countdown,
689     in a format suitable for Date.parse()
690     """
691     from datetime import datetime
692     return HttpResponse(datetime.now().strftime('%Y/%m/%d %H:%M:%S'))