apps/catalogue/utils.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 from __future__ import with_statement
   6
   7 import random
   8 import time
   9 from base64 import urlsafe_b64encode
  10
  11 from django.http import HttpResponse, HttpResponseRedirect, Http404, HttpResponsePermanentRedirect
  12 from django.core.files.uploadedfile import UploadedFile
  13 from django.core.files.base import File
  14 from django.core.files.storage import DefaultStorage
  15 from django.utils.hashcompat import sha_constructor
  16 from django.conf import settings
  17 from celery.task import task
  18 from os import mkdir, path, unlink
  19 from errno import EEXIST, ENOENT
  20 from fcntl import flock, LOCK_EX
  21 from zipfile import ZipFile
  22
  23 from librarian import DocProvider
  24 from reporting.utils import read_chunks
  25 from celery.task import task
  26 import catalogue.models
  27
  28 # Use the system (hardware-based) random number generator if it exists.
  29 if hasattr(random, 'SystemRandom'):
  30     randrange = random.SystemRandom().randrange
  31 else:
  32     randrange = random.randrange
  33 MAX_SESSION_KEY = 18446744073709551616L     # 2 << 63
  34
  35
  36 def get_random_hash(seed):
  37     sha_digest = sha_constructor('%s%s%s%s' %
  38         (randrange(0, MAX_SESSION_KEY), time.time(), unicode(seed).encode('utf-8', 'replace'),
  39         settings.SECRET_KEY)).digest()
  40     return urlsafe_b64encode(sha_digest).replace('=', '').replace('_', '-').lower()
  41
  42
  43 def split_tags(tags):
  44     result = {}
  45     for tag in tags:
  46         result.setdefault(tag.category, []).append(tag)
  47     return result
  48
  49
  50 class ExistingFile(UploadedFile):
  51
  52     def __init__(self, path, *args, **kwargs):
  53         self.path = path
  54         return super(ExistingFile, self).__init__(*args, **kwargs)
  55
  56     def temporary_file_path(self):
  57         return self.path
  58
  59     def close(self):
  60         pass
  61
  62
  63 class ORMDocProvider(DocProvider):
  64     """Used for getting books' children."""
  65
  66     def __init__(self, book):
  67         self.book = book
  68
  69     def by_slug(self, slug):
  70         if slug == self.book.slug:
  71             return self.book.xml_file
  72         else:
  73             return type(self.book).objects.get(slug=slug).xml_file
  74
  75
  76 class LockFile(object):
  77     """
  78     A file lock monitor class; createas an ${objname}.lock
  79     file in directory dir, and locks it exclusively.
  80     To be used in 'with' construct.
  81     """
  82     def __init__(self, dir, objname):
  83         self.lockname = path.join(dir, objname + ".lock")
  84
  85     def __enter__(self):
  86         self.lock = open(self.lockname, 'w')
  87         flock(self.lock, LOCK_EX)
  88
  89     def __exit__(self, *err):
  90         try:
  91             unlink(self.lockname)
  92         except OSError as oe:
  93             if oe.errno != oe.EEXIST:
  94                 raise oe
  95         self.lock.close()
  96
  97
  98 @task
  99 def create_zip(paths, zip_slug):
 100     """
 101     Creates a zip in MEDIA_ROOT/zip directory containing files from path.
 102     Resulting archive filename is ${zip_slug}.zip
 103     Returns it's path relative to MEDIA_ROOT (no initial slash)
 104     """
 105     # directory to store zip files
 106     zip_path = path.join(settings.MEDIA_ROOT, 'zip')
 107
 108     try:
 109         mkdir(zip_path)
 110     except OSError as oe:
 111         if oe.errno != EEXIST:
 112             raise oe
 113     zip_filename = zip_slug + ".zip"
 114
 115     with LockFile(zip_path, zip_slug):
 116         if not path.exists(path.join(zip_path, zip_filename)):
 117             zipf = ZipFile(path.join(zip_path, zip_filename), 'w')
 118             try:
 119                 for arcname, p in paths:
 120                     if arcname is None:
 121                         arcname = path.basename(p)
 122                     zipf.write(p, arcname)
 123             finally:
 124                 zipf.close()
 125
 126         return 'zip/' + zip_filename
 127
 128
 129 def remove_zip(zip_slug):
 130     """
 131     removes the ${zip_slug}.zip file from zip store.
 132     """
 133     zip_file = path.join(settings.MEDIA_ROOT, 'zip', zip_slug + '.zip')
 134     try:
 135         unlink(zip_file)
 136     except OSError as oe:
 137         if oe.errno != ENOENT:
 138             raise oe
 139
 140
 141 class AttachmentHttpResponse(HttpResponse):
 142     """Response serving a file to be downloaded.
 143     """
 144     def __init__ (self, file_path, file_name, mimetype):
 145         super(AttachmentHttpResponse, self).__init__(mimetype=mimetype)
 146         self['Content-Disposition'] = 'attachment; filename=%s' % file_name
 147         self.file_path = file_path
 148         self.file_name = file_name
 149
 150         with open(DefaultStorage().path(self.file_path)) as f:
 151             for chunk in read_chunks(f):
 152                 self.write(chunk)
 153
 154 @task
 155 def async_build_pdf(book_id, customizations, file_name):
 156     """
 157     A celery task to generate pdf files.
 158     Accepts the same args as Book.build_pdf, but with book id as first parameter
 159     instead of Book instance
 160     """
 161     book = catalogue.models.Book.objects.get(id=book_id)
 162     print "will gen %s" % DefaultStorage().path(file_name)
 163     if not DefaultStorage().exists(file_name):
 164         book.build_pdf(customizations=customizations, file_name=file_name)
 165     print "done."