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_and_lang(self, slug, language):
  70         if slug == self.book.slug and language == self.language:
  71             return open(self.book.xml_file.path)
  72         else:
  73             return type(self.book).objects.get(
  74                     slug=slug, language=language).xml_file
  75
  76
  77 class LockFile(object):
  78     """
  79     A file lock monitor class; createas an ${objname}.lock
  80     file in directory dir, and locks it exclusively.
  81     To be used in 'with' construct.
  82     """
  83     def __init__(self, dir, objname):
  84         self.lockname = path.join(dir, objname + ".lock")
  85
  86     def __enter__(self):
  87         self.lock = open(self.lockname, 'w')
  88         flock(self.lock, LOCK_EX)
  89
  90     def __exit__(self, *err):
  91         try:
  92             unlink(self.lockname)
  93         except OSError as oe:
  94             if oe.errno != oe.EEXIST:
  95                 raise oe
  96         self.lock.close()
  97
  98
  99 @task
 100 def create_zip(paths, zip_slug):
 101     """
 102     Creates a zip in MEDIA_ROOT/zip directory containing files from path.
 103     Resulting archive filename is ${zip_slug}.zip
 104     Returns it's path relative to MEDIA_ROOT (no initial slash)
 105     """
 106     # directory to store zip files
 107     zip_path = path.join(settings.MEDIA_ROOT, 'zip')
 108
 109     try:
 110         mkdir(zip_path)
 111     except OSError as oe:
 112         if oe.errno != EEXIST:
 113             raise oe
 114     zip_filename = zip_slug + ".zip"
 115
 116     with LockFile(zip_path, zip_slug):
 117         if not path.exists(path.join(zip_path, zip_filename)):
 118             zipf = ZipFile(path.join(zip_path, zip_filename), 'w')
 119             try:
 120                 for arcname, p in paths:
 121                     if arcname is None:
 122                         arcname = path.basename(p)
 123                     zipf.write(p, arcname)
 124             finally:
 125                 zipf.close()
 126
 127         return 'zip/' + zip_filename
 128
 129
 130 def remove_zip(zip_slug):
 131     """
 132     removes the ${zip_slug}.zip file from zip store.
 133     """
 134     zip_file = path.join(settings.MEDIA_ROOT, 'zip', zip_slug + '.zip')
 135     try:
 136         unlink(zip_file)
 137     except OSError as oe:
 138         if oe.errno != ENOENT:
 139             raise oe
 140
 141
 142 class AttachmentHttpResponse(HttpResponse):
 143     """Response serving a file to be downloaded.
 144     """
 145     def __init__ (self, file_path, file_name, mimetype):
 146         super(AttachmentHttpResponse, self).__init__(mimetype=mimetype)
 147         self['Content-Disposition'] = 'attachment; filename=%s' % file_name
 148         self.file_path = file_path
 149         self.file_name = file_name
 150
 151         with open(DefaultStorage().path(self.file_path)) as f:
 152             for chunk in read_chunks(f):
 153                 self.write(chunk)
 154
 155 @task
 156 def async_build_pdf(book_id, customizations, file_name):
 157     """
 158     A celery task to generate pdf files.
 159     Accepts the same args as Book.build_pdf, but with book id as first parameter
 160     instead of Book instance
 161     """
 162     book = catalogue.models.Book.objects.get(id=book_id)
 163     print "will gen %s" % DefaultStorage().path(file_name)
 164     if not DefaultStorage().exists(file_name):
 165         book.build_pdf(customizations=customizations, file_name=file_name)
 166     print "done."