Moving forward.
[wolnelektury.git] / src / catalogue / models / book.py
index af4c941..85cfd63 100644 (file)
@@ -2,70 +2,52 @@
 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
 #
 from collections import OrderedDict
+import json
 from datetime import date, timedelta
 from random import randint
 import os.path
 import re
 from urllib.request import urlretrieve
+from django.apps import apps
 from django.conf import settings
 from django.db import connection, models, transaction
 import django.dispatch
 from django.contrib.contenttypes.fields import GenericRelation
+from django.template.loader import render_to_string
 from django.urls import reverse
-from django.utils.translation import ugettext_lazy as _, get_language
-from django.utils.deconstruct import deconstructible
-import jsonfield
+from django.utils.translation import gettext_lazy as _, get_language
 from fnpdjango.storage import BofhFileSystemStorage
-
+from lxml import html
 from librarian.cover import WLCover
 from librarian.html import transform_abstrakt
 from newtagging import managers
 from catalogue import constants
-from catalogue.fields import EbookField
+from catalogue import fields
 from catalogue.models import Tag, Fragment, BookMedia
 from catalogue.utils import create_zip, gallery_url, gallery_path, split_tags, get_random_hash
 from catalogue.models.tag import prefetched_relations
 from catalogue import app_settings
-from catalogue import tasks
 from wolnelektury.utils import makedirs, cached_render, clear_cached_renders
 
 bofh_storage = BofhFileSystemStorage()
 
 
-@deconstructible
-class UploadToPath(object):
-    def __init__(self, path):
-        self.path = path
-
-    def __call__(self, instance, filename):
-        return self.path % instance.slug
-
-
-_cover_upload_to = UploadToPath('book/cover/%s.jpg')
-_cover_thumb_upload_to = UploadToPath('book/cover_thumb/%s.jpg')
-_cover_api_thumb_upload_to = UploadToPath('book/cover_api_thumb/%s.jpg')
-_simple_cover_upload_to = UploadToPath('book/cover_simple/%s.jpg')
-
-
-def _ebook_upload_to(upload_path):
-    return UploadToPath(upload_path)
-
-
 class Book(models.Model):
     """Represents a book imported from WL-XML."""
     title = models.CharField(_('title'), max_length=32767)
     sort_key = models.CharField(_('sort key'), max_length=120, db_index=True, editable=False)
     sort_key_author = models.CharField(
-        _('sort key by author'), max_length=120, db_index=True, editable=False, default=u'')
+        _('sort key by author'), max_length=120, db_index=True, editable=False, default='')
     slug = models.SlugField(_('slug'), max_length=120, db_index=True, unique=True)
     common_slug = models.SlugField(_('slug'), max_length=120, db_index=True)
     language = models.CharField(_('language code'), max_length=3, db_index=True, default=app_settings.DEFAULT_LANGUAGE)
     description = models.TextField(_('description'), blank=True)
     abstract = models.TextField(_('abstract'), blank=True)
+    toc = models.TextField(_('toc'), blank=True)
     created_at = models.DateTimeField(_('creation date'), auto_now_add=True, db_index=True)
     changed_at = models.DateTimeField(_('change date'), auto_now=True, db_index=True)
     parent_number = models.IntegerField(_('parent number'), default=0)
-    extra_info = jsonfield.JSONField(_('extra information'), default={})
+    extra_info = models.TextField(_('extra information'), default='{}')
     gazeta_link = models.CharField(blank=True, max_length=240)
     wiki_link = models.CharField(blank=True, max_length=240)
     print_on_demand = models.BooleanField(_('print on demand'), default=False)
@@ -74,29 +56,27 @@ class Book(models.Model):
     preview = models.BooleanField(_('preview'), default=False)
     preview_until = models.DateField(_('preview until'), blank=True, null=True)
     preview_key = models.CharField(max_length=32, blank=True, null=True)
+    findable = models.BooleanField(_('findable'), default=True, db_index=True)
 
     # files generated during publication
-    cover = EbookField(
-        'cover', _('cover'),
-        null=True, blank=True,
-        upload_to=_cover_upload_to,
-        storage=bofh_storage, max_length=255)
+    xml_file = fields.XmlField(storage=bofh_storage, with_etag=False)
+    html_file = fields.HtmlField(storage=bofh_storage)
+    fb2_file = fields.Fb2Field(storage=bofh_storage)
+    txt_file = fields.TxtField(storage=bofh_storage)
+    epub_file = fields.EpubField(storage=bofh_storage)
+    mobi_file = fields.MobiField(storage=bofh_storage)
+    pdf_file = fields.PdfField(storage=bofh_storage)
+
+    cover = fields.CoverField(_('cover'), storage=bofh_storage)
     # Cleaner version of cover for thumbs
-    cover_thumb = EbookField(
-        'cover_thumb', _('cover thumbnail'),
-        null=True, blank=True,
-        upload_to=_cover_thumb_upload_to,
-        max_length=255)
-    cover_api_thumb = EbookField(
-        'cover_api_thumb', _('cover thumbnail for mobile app'),
-        null=True, blank=True,
-        upload_to=_cover_api_thumb_upload_to,
-        max_length=255)
-    simple_cover = EbookField(
-        'simple_cover', _('cover for mobile app'),
-        null=True, blank=True,
-        upload_to=_simple_cover_upload_to,
-        max_length=255)
+    cover_clean = fields.CoverCleanField(_('clean cover'))
+    cover_thumb = fields.CoverThumbField(_('cover thumbnail'))
+    cover_api_thumb = fields.CoverApiThumbField(
+        _('cover thumbnail for mobile app'))
+    simple_cover = fields.SimpleCoverField(_('cover for mobile app'))
+    cover_ebookpoint = fields.CoverEbookpointField(
+        _('cover for Ebookpoint'))
+
     ebook_formats = constants.EBOOK_FORMATS
     formats = ebook_formats + ['html', 'xml']
 
@@ -116,6 +96,8 @@ class Book(models.Model):
 
     SORT_KEY_SEP = '$'
 
+    is_book = True
+
     class AlreadyExists(Exception):
         pass
 
@@ -128,6 +110,9 @@ class Book(models.Model):
     def __str__(self):
         return self.title
 
+    def get_extra_info_json(self):
+        return json.loads(self.extra_info or '{}')
+
     def get_initial(self):
         try:
             return re.search(r'\w', self.title, re.U).group(0)
@@ -168,8 +153,14 @@ class Book(models.Model):
     def genre_unicode(self):
         return self.tag_unicode('genre')
 
+    def translators(self):
+        translators = self.get_extra_info_json().get('translators') or []
+        return [
+            '\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators
+        ]
+
     def translator(self):
-        translators = self.extra_info.get('translators')
+        translators = self.get_extra_info_json().get('translators')
         if not translators:
             return None
         if len(translators) > 3:
@@ -177,10 +168,35 @@ class Book(models.Model):
             others = ' i inni'
         else:
             others = ''
-        return ', '.join(u'\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators) + others
+        return ', '.join('\xa0'.join(reversed(translator.split(', ', 1))) for translator in translators) + others
 
     def cover_source(self):
-        return self.extra_info.get('cover_source', self.parent.cover_source() if self.parent else '')
+        return self.get_extra_info_json().get('cover_source', self.parent.cover_source() if self.parent else '')
+
+    @property
+    def isbn_pdf(self):
+        return self.get_extra_info_json().get('isbn_pdf')
+
+    @property
+    def isbn_epub(self):
+        return self.get_extra_info_json().get('isbn_epub')
+
+    @property
+    def isbn_mobi(self):
+        return self.get_extra_info_json().get('isbn_mobi')
+
+    def is_accessible_to(self, user):
+        if not self.preview:
+            return True
+        if not user.is_authenticated:
+            return False
+        Membership = apps.get_model('club', 'Membership')
+        if Membership.is_active_for(user):
+            return True
+        Funding = apps.get_model('funding', 'Funding')
+        if Funding.objects.filter(user=user, offer__book=self):
+            return True
+        return False
 
     def save(self, force_insert=False, force_update=False, **kwargs):
         from sortify import sortify
@@ -191,11 +207,11 @@ class Book(models.Model):
         try:
             author = self.authors().first().sort_key
         except AttributeError:
-            author = u''
+            author = ''
         self.sort_key_author = author
 
         self.cached_author = self.tag_unicode('author')
-        self.has_audience = 'audience' in self.extra_info
+        self.has_audience = 'audience' in self.get_extra_info_json()
 
         if self.preview and not self.preview_key:
             self.preview_key = get_random_hash(self.slug)[:32]
@@ -213,6 +229,64 @@ class Book(models.Model):
     def gallery_url(self):
         return gallery_url(self.slug)
 
+    def get_first_text(self):
+        if self.html_file:
+            return self
+        child = self.children.all().order_by('parent_number').first()
+        if child is not None:
+            return child.get_first_text()
+
+    def get_last_text(self):
+        if self.html_file:
+            return self
+        child = self.children.all().order_by('parent_number').last()
+        if child is not None:
+            return child.get_last_text()
+
+    def get_prev_text(self):
+        if not self.parent:
+            return None
+        sibling = self.parent.children.filter(parent_number__lt=self.parent_number).order_by('-parent_number').first()
+        if sibling is not None:
+            return sibling.get_last_text()
+
+        if self.parent.html_file:
+            return self.parent
+
+        return self.parent.get_prev_text()
+
+    def get_next_text(self, inside=True):
+        if inside:
+            child = self.children.order_by('parent_number').first()
+            if child is not None:
+                return child.get_first_text()
+
+        if not self.parent:
+            return None
+        sibling = self.parent.children.filter(parent_number__gt=self.parent_number).order_by('parent_number').first()
+        if sibling is not None:
+            return sibling.get_first_text()
+        return self.parent.get_next_text(inside=False)
+
+    def get_child_audiobook(self):
+        BookMedia = apps.get_model('catalogue', 'BookMedia')
+        if not BookMedia.objects.filter(book__ancestor=self).exists():
+            return None
+        for child in self.children.order_by('parent_number').all():
+            if child.has_mp3_file():
+                return child
+            child_sub = child.get_child_audiobook()
+            if child_sub is not None:
+                return child_sub
+
+    def get_siblings(self):
+        if not self.parent:
+            return []
+        return self.parent.children.all().order_by('parent_number')
+
+    def get_children(self):
+        return self.children.all().order_by('parent_number')
+
     @property
     def name(self):
         return self.title
@@ -234,6 +308,12 @@ class Book(models.Model):
 
     @staticmethod
     def format_audio_length(seconds):
+        """
+        >>> Book.format_audio_length(1)
+        '0:01'
+        >>> Book.format_audio_length(3661)
+        '1:01:01'
+        """
         if seconds < 60*60:
             minutes = seconds // 60
             seconds = seconds % 60
@@ -280,6 +360,9 @@ class Book(models.Model):
     def get_daisy(self):
         return self.get_media("daisy")
 
+    def get_audio_epub(self):
+        return self.get_media("audio.epub")
+
     def media_url(self, format_):
         media = self.get_media(format_)
         if media:
@@ -331,6 +414,32 @@ class Book(models.Model):
     has_daisy_file.short_description = 'DAISY'
     has_daisy_file.boolean = True
 
+    def has_sync_file(self):
+        return self.has_media("sync")
+
+    def get_sync(self):
+        with self.get_media('sync').first().file.open('r') as f:
+            sync = f.read().split('\n')
+        offset = float(sync[0])
+        items = []
+        for line in sync[1:]:
+            if not line:
+                continue
+            start, end, elid = line.split()
+            items.append([elid, float(start) + offset])
+        return json.dumps(items)
+    
+    def has_audio_epub_file(self):
+        return self.has_media("audio.epub")
+
+    @property
+    def media_daisy(self):
+        return self.get_media('daisy')
+
+    @property
+    def media_audio_epub(self):
+        return self.get_media('audio.epub')
+
     def get_audiobooks(self):
         ogg_files = {}
         for m in self.media.filter(type='ogg').order_by().iterator():
@@ -338,15 +447,17 @@ class Book(models.Model):
 
         audiobooks = []
         projects = set()
+        total_duration = 0
         for mp3 in self.media.filter(type='mp3').iterator():
             # ogg files are always from the same project
-            meta = mp3.extra_info
+            meta = mp3.get_extra_info_json()
             project = meta.get('project')
             if not project:
                 # temporary fallback
-                project = u'CzytamySłuchając'
+                project = 'CzytamySłuchając'
 
             projects.add((project, meta.get('funded_by', '')))
+            total_duration += mp3.duration or 0
 
             media = {'mp3': mp3}
 
@@ -356,7 +467,11 @@ class Book(models.Model):
             audiobooks.append(media)
 
         projects = sorted(projects)
-        return audiobooks, projects
+        total_duration = '%d:%02d' % (
+            total_duration // 60,
+            total_duration % 60
+        )
+        return audiobooks, projects, total_duration
 
     def wldocument(self, parse_dublincore=True, inherit=True):
         from catalogue.import_utils import ORMDocProvider
@@ -373,25 +488,50 @@ class Book(models.Model):
             parse_dublincore=parse_dublincore,
             meta_fallbacks=meta_fallbacks)
 
+    def wldocument2(self):
+        from catalogue.import_utils import ORMDocProvider
+        from librarian.document import WLDocument
+        doc = WLDocument(
+            self.xml_file.path,
+            provider=ORMDocProvider(self)
+        )
+        doc.meta.update(self.cover_info())
+        return doc
+
+
     @staticmethod
     def zip_format(format_):
         def pretty_file_name(book):
             return "%s/%s.%s" % (
-                book.extra_info['author'],
+                book.get_extra_info_json()['author'],
                 book.slug,
                 format_)
 
         field_name = "%s_file" % format_
-        books = Book.objects.filter(parent=None).exclude(**{field_name: ""}).exclude(preview=True)
+        field = getattr(Book, field_name)
+        books = Book.objects.filter(parent=None).exclude(**{field_name: ""}).exclude(preview=True).exclude(findable=False)
         paths = [(pretty_file_name(b), getattr(b, field_name).path) for b in books.iterator()]
-        return create_zip(paths, app_settings.FORMAT_ZIPS[format_])
+        return create_zip(paths, field.ZIP)
 
     def zip_audiobooks(self, format_):
         bm = BookMedia.objects.filter(book=self, type=format_)
-        paths = map(lambda bm: (None, bm.file.path), bm)
-        return create_zip(paths, "%s_%s" % (self.slug, format_))
+        paths = map(lambda bm: (bm.get_nice_filename(), bm.file.path), bm)
+        licenses = set()
+        for m in bm:
+            license = constants.LICENSES.get(
+                m.get_extra_info_json().get('license'), {}
+            ).get('locative')
+            if license:
+                licenses.add(license)
+        readme = render_to_string('catalogue/audiobook_zip_readme.txt', {
+            'licenses': licenses,
+            'meta': self.wldocument2().meta,
+        })
+        return create_zip(paths, "%s_%s" % (self.slug, format_), {'informacje.txt': readme})
 
     def search_index(self, book_info=None, index=None, index_tags=True, commit=True):
+        if not self.findable:
+            return
         if index is None:
             from search.index import Index
             index = Index()
@@ -407,6 +547,7 @@ class Book(models.Model):
 
     # will make problems in conjunction with paid previews
     def download_pictures(self, remote_gallery_url):
+        # This is only needed for legacy relative image paths.
         gallery_path = self.gallery_path()
         # delete previous files, so we don't include old files in ebooks
         if os.path.isdir(gallery_path):
@@ -418,6 +559,8 @@ class Book(models.Model):
             makedirs(gallery_path)
             for ilustr in ilustr_elements:
                 ilustr_src = ilustr.get('src')
+                if '/' in ilustr_src:
+                    continue
                 ilustr_path = os.path.join(gallery_path, ilustr_src)
                 urlretrieve('%s/%s' % (remote_gallery_url, ilustr_src), ilustr_path)
 
@@ -428,6 +571,20 @@ class Book(models.Model):
         else:
             self.abstract = ''
 
+    def load_toc(self):
+        self.toc = ''
+        if self.html_file:
+            parser = html.HTMLParser(encoding='utf-8')
+            tree = html.parse(self.html_file.path, parser=parser)
+            toc = tree.find('//div[@id="toc"]/ol')
+            if toc is None or not len(toc):
+                return
+            html_link = reverse('book_text', args=[self.slug])
+            for a in toc.findall('.//a'):
+                a.attrib['href'] = html_link + a.attrib['href']
+            self.toc = html.tostring(toc, encoding='unicode')
+            # div#toc
+
     @classmethod
     def from_xml_file(cls, xml_file, **kwargs):
         from django.core.files import File
@@ -446,7 +603,9 @@ class Book(models.Model):
 
     @classmethod
     def from_text_and_meta(cls, raw_file, book_info, overwrite=False, dont_build=None, search_index=True,
-                           search_index_tags=True, remote_gallery_url=None, days=0):
+                           search_index_tags=True, remote_gallery_url=None, days=0, findable=True):
+        from catalogue import tasks
+
         if dont_build is None:
             dont_build = set()
         dont_build = set.union(set(dont_build), set(app_settings.DONT_BUILD))
@@ -484,14 +643,16 @@ class Book(models.Model):
         if book.preview:
             book.xml_file.set_readable(False)
 
+        book.findable = findable
         book.language = book_info.language
         book.title = book_info.title
         if book_info.variant_of:
             book.common_slug = book_info.variant_of.slug
         else:
             book.common_slug = book.slug
-        book.extra_info = book_info.to_dict()
+        book.extra_info = json.dumps(book_info.to_dict())
         book.load_abstract()
+        book.load_toc()
         book.save()
 
         meta_tags = Tag.tags_from_info(book_info)
@@ -534,9 +695,11 @@ class Book(models.Model):
         # Build cover.
         if 'cover' not in dont_build:
             book.cover.build_delay()
+            book.cover_clean.build_delay()
             book.cover_thumb.build_delay()
             book.cover_api_thumb.build_delay()
             book.simple_cover.build_delay()
+            book.cover_ebookpoint.build_delay()
 
         # Build HTML and ebooks.
         book.html_file.build_delay()
@@ -548,16 +711,62 @@ class Book(models.Model):
             if format_ not in dont_build:
                 getattr(book, '%s_file' % format_).build_delay()
 
-        if not settings.NO_SEARCH_INDEX and search_index:
+        if not settings.NO_SEARCH_INDEX and search_index and findable:
             tasks.index_book.delay(book.id, book_info=book_info, index_tags=search_index_tags)
 
         for child in notify_cover_changed:
             child.parent_cover_changed()
 
         book.update_popularity()
+        tasks.update_references.delay(book.id)
+
         cls.published.send(sender=cls, instance=book)
         return book
 
+    def get_master(self):
+        master_tags = [
+            'opowiadanie',
+            'powiesc',
+            'dramat_wierszowany_l',
+            'dramat_wierszowany_lp',
+            'dramat_wspolczesny', 'liryka_l', 'liryka_lp',
+            'wywiad',
+        ]
+        from librarian.parser import WLDocument
+        wld = WLDocument.from_file(self.xml_file.path, parse_dublincore=False)
+        root = wld.edoc.getroot()
+        for master in root.iter():
+            if master.tag in master_tags:
+                return master
+
+    def update_references(self):
+        from references.models import Entity, Reference
+        master = self.get_master()
+        if master is None:
+            master = []
+        found = set()
+        for i, sec in enumerate(master):
+            for ref in sec.findall('.//ref'):
+                href = ref.attrib.get('href', '')
+                if not href or href in found:
+                    continue
+                found.add(href)
+                entity, created = Entity.objects.get_or_create(
+                    uri=href
+                )
+                ref, created = Reference.objects.get_or_create(
+                    book=self,
+                    entity=entity
+                )
+                ref.first_section = 'sec%d' % (i + 1)
+                entity.populate()
+                entity.save()
+        Reference.objects.filter(book=self).exclude(entity__uri__in=found).delete()
+
+    @property
+    def references(self):
+        return self.reference_set.all().select_related('entity')
+
     @classmethod
     @transaction.atomic
     def repopulate_ancestors(cls):
@@ -591,6 +800,15 @@ class Book(models.Model):
                     b.ancestor.add(parent)
                     parent = parent.parent
 
+    @property
+    def ancestors(self):
+        if self.parent:
+            for anc in self.parent.ancestors:
+                yield anc
+            yield self.parent
+        else:
+            return []
+
     def clear_cache(self):
         clear_cached_renders(self.mini_box)
         clear_cached_renders(self.mini_box_nolink)
@@ -603,7 +821,7 @@ class Book(models.Model):
         need = False
         info = {}
         for field in ('cover_url', 'cover_by', 'cover_source'):
-            val = self.extra_info.get(field)
+            val = self.get_extra_info_json().get(field)
             if val:
                 info[field] = val
             else:
@@ -617,16 +835,18 @@ class Book(models.Model):
     def related_themes(self):
         return Tag.objects.usage_for_queryset(
             Fragment.objects.filter(models.Q(book=self) | models.Q(book__ancestor=self)),
-            counts=True).filter(category='theme')
+            counts=True).filter(category='theme').order_by('-count')
 
     def parent_cover_changed(self):
         """Called when parent book's cover image is changed."""
         if not self.cover_info(inherit=False):
             if 'cover' not in app_settings.DONT_BUILD:
                 self.cover.build_delay()
+                self.cover_clean.build_delay()
                 self.cover_thumb.build_delay()
                 self.cover_api_thumb.build_delay()
                 self.simple_cover.build_delay()
+                self.cover_ebookpoint.build_delay()
             for format_ in constants.EBOOK_FORMATS_WITH_COVERS:
                 if format_ not in app_settings.DONT_BUILD:
                     getattr(self, '%s_file' % format_).build_delay()
@@ -635,7 +855,7 @@ class Book(models.Model):
 
     def other_versions(self):
         """Find other versions (i.e. in other languages) of the book."""
-        return type(self).objects.filter(common_slug=self.common_slug).exclude(pk=self.pk)
+        return type(self).objects.filter(common_slug=self.common_slug, findable=True).exclude(pk=self.pk)
 
     def parents(self):
         books = []
@@ -657,7 +877,7 @@ class Book(models.Model):
         return ', '.join(names)
 
     def publisher(self):
-        publisher = self.extra_info['publisher']
+        publisher = self.get_extra_info_json()['publisher']
         if isinstance(publisher, str):
             return publisher
         elif isinstance(publisher, list):
@@ -672,7 +892,7 @@ class Book(models.Model):
 
         """
         objects = cls.tagged.with_all(tags)
-        return objects.exclude(ancestor__in=objects)
+        return objects.filter(findable=True).exclude(ancestor__in=objects)
 
     @classmethod
     def book_list(cls, book_filter=None):
@@ -683,7 +903,7 @@ class Book(models.Model):
         """
 
         books_by_parent = {}
-        books = cls.objects.order_by('parent_number', 'sort_key').only('title', 'parent', 'slug', 'extra_info')
+        books = cls.objects.filter(findable=True).order_by('parent_number', 'sort_key').only('title', 'parent', 'slug', 'extra_info')
         if book_filter:
             books = books.filter(book_filter).distinct()
 
@@ -713,39 +933,50 @@ class Book(models.Model):
         return books_by_author, orphans, books_by_parent
 
     _audiences_pl = {
-        "SP": (1, u"szkoła podstawowa"),
-        "SP1": (1, u"szkoła podstawowa"),
-        "SP2": (1, u"szkoła podstawowa"),
-        "SP3": (1, u"szkoła podstawowa"),
-        "P": (1, u"szkoła podstawowa"),
-        "G": (2, u"gimnazjum"),
-        "L": (3, u"liceum"),
-        "LP": (3, u"liceum"),
+        "SP": (1, "szkoła podstawowa"),
+        "SP1": (1, "szkoła podstawowa"),
+        "SP2": (1, "szkoła podstawowa"),
+        "SP3": (1, "szkoła podstawowa"),
+        "P": (1, "szkoła podstawowa"),
+        "G": (2, "gimnazjum"),
+        "L": (3, "liceum"),
+        "LP": (3, "liceum"),
     }
 
     def audiences_pl(self):
-        audiences = self.extra_info.get('audiences', [])
+        audiences = self.get_extra_info_json().get('audiences', [])
         audiences = sorted(set([self._audiences_pl.get(a, (99, a)) for a in audiences]))
         return [a[1] for a in audiences]
 
     def stage_note(self):
-        stage = self.extra_info.get('stage')
+        stage = self.get_extra_info_json().get('stage')
         if stage and stage < '0.4':
             return (_('This work needs modernisation'),
                     reverse('infopage', args=['wymagajace-uwspolczesnienia']))
         else:
             return None, None
 
-    def choose_fragment(self):
+    def choose_fragments(self, number):
         fragments = self.fragments.order_by()
         fragments_count = fragments.count()
         if not fragments_count and self.children.exists():
             fragments = Fragment.objects.filter(book__ancestor=self).order_by()
             fragments_count = fragments.count()
         if fragments_count:
-            return fragments[randint(0, fragments_count - 1)]
+            if fragments_count > number:
+                offset = randint(0, fragments_count - number)
+            else:
+                offset = 0
+            return fragments[offset : offset + number]
         elif self.parent:
-            return self.parent.choose_fragment()
+            return self.parent.choose_fragments(number)
+        else:
+            return []
+
+    def choose_fragment(self):
+        fragments = self.choose_fragments(1)
+        if fragments:
+            return fragments[0]
         else:
             return None
 
@@ -786,7 +1017,7 @@ class Book(models.Model):
         return self.SORT_KEY_SEP.join((self.sort_key_author, self.sort_key, str(self.id)))
 
     def cover_color(self):
-        return WLCover.epoch_colors.get(self.extra_info.get('epoch'), '#000000')
+        return WLCover.epoch_colors.get(self.get_extra_info_json().get('epoch'), '#000000')
 
     @cached_render('catalogue/book_mini_box.html')
     def mini_box(self):
@@ -801,26 +1032,6 @@ class Book(models.Model):
             'no_link': True,
         }
 
-def add_file_fields():
-    for format_ in Book.formats:
-        field_name = "%s_file" % format_
-        # This weird globals() assignment makes Django migrations comfortable.
-        _upload_to = _ebook_upload_to('book/%s/%%s.%s' % (format_, format_))
-        _upload_to.__name__ = '_%s_upload_to' % format_
-        globals()[_upload_to.__name__] = _upload_to
-
-        EbookField(
-            format_, _("%s file" % format_.upper()),
-            upload_to=_upload_to,
-            storage=bofh_storage,
-            max_length=255,
-            blank=True,
-            default=''
-        ).contribute_to_class(Book, field_name)
-
-
-add_file_fields()
-
 
 class BookPopularity(models.Model):
     book = models.OneToOneField(Book, models.CASCADE, related_name='popularity')