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