src/wolnelektury/utils.py

   1 # This file is part of Wolnelektury, licensed under GNU Affero GPLv3 or later.
   2 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
   3 #
   4 import codecs
   5 import csv
   6 from functools import wraps
   7 from inspect import getargspec
   8 from io import BytesIO
   9 import json
  10 import os
  11 import pytz
  12 import re
  13
  14 from django.conf import settings
  15 from django.core.cache import cache
  16 from django.core.mail import send_mail
  17 from django.http import HttpResponse
  18 from django.template.loader import render_to_string
  19 from django.utils import timezone
  20 from django.utils.translation import get_language
  21 from django.conf import settings
  22 from django.utils.safestring import mark_safe
  23 from django.utils.translation import ugettext
  24
  25
  26 tz = pytz.timezone(settings.TIME_ZONE)
  27
  28
  29 def localtime_to_utc(localtime):
  30     return timezone.utc.normalize(
  31         tz.localize(localtime)
  32     )
  33
  34
  35 def utc_for_js(dt):
  36     return dt.strftime('%Y/%m/%d %H:%M:%S UTC')
  37
  38
  39 def makedirs(path):
  40     if not os.path.isdir(path):
  41         os.makedirs(path)
  42
  43
  44 def stringify_keys(dictionary):
  45     return dict((keyword.encode('ascii'), value)
  46                 for keyword, value in dictionary.items())
  47
  48
  49 def json_encode(obj, sort_keys=True, ensure_ascii=False):
  50     return json.dumps(obj, sort_keys=sort_keys, ensure_ascii=ensure_ascii)
  51
  52
  53 def json_decode(obj):
  54     return json.loads(obj)
  55
  56
  57 def json_decode_fallback(value):
  58     try:
  59         return json_decode(value)
  60     except ValueError:
  61         return value
  62
  63
  64 class AjaxError(Exception):
  65     pass
  66
  67
  68 def ajax(login_required=False, method=None, template=None, permission_required=None):
  69     def decorator(fun):
  70         @wraps(fun)
  71         def ajax_view(request):
  72             kwargs = {}
  73             request_params = None
  74             if method == 'post':
  75                 request_params = request.POST
  76             elif method == 'get':
  77                 request_params = request.GET
  78             fun_params, xx, fun_kwargs, defaults = getargspec(fun)
  79             if defaults:
  80                 required_params = fun_params[1:-len(defaults)]
  81             else:
  82                 required_params = fun_params[1:]
  83             missing_params = set(required_params) - set(request_params)
  84             if missing_params:
  85                 res = {
  86                     'result': 'missing params',
  87                     'missing': ', '.join(missing_params),
  88                 }
  89             else:
  90                 if request_params:
  91                     request_params = dict(
  92                         (key, json_decode_fallback(value))
  93                         for key, value in request_params.items()
  94                         if fun_kwargs or key in fun_params)
  95                     kwargs.update(stringify_keys(request_params))
  96                 res = None
  97                 if login_required and not request.user.is_authenticated:
  98                     res = {'result': 'logout'}
  99                 if (permission_required and
 100                         not request.user.has_perm(permission_required)):
 101                     res = {'result': 'access denied'}
 102             if not res:
 103                 try:
 104                     res = fun(request, **kwargs)
 105                     if res and template:
 106                         res = {'html': render_to_string(template, res, request=request)}
 107                 except AjaxError as e:
 108                     res = {'result': e.args[0]}
 109             if 'result' not in res:
 110                 res['result'] = 'ok'
 111             return HttpResponse(json_encode(res), content_type='application/json; charset=utf-8',
 112                                 status=200 if res['result'] == 'ok' else 400)
 113
 114         return ajax_view
 115
 116     return decorator
 117
 118
 119 def send_noreply_mail(subject, message, recipient_list, **kwargs):
 120     send_mail(
 121         u'[WolneLektury] ' + subject,
 122         message + u"\n\n-- \n" + ugettext(u'Message sent automatically. Please do not reply.'),
 123         'no-reply@wolnelektury.pl', recipient_list, **kwargs)
 124
 125
 126 # source: https://docs.python.org/2/library/csv.html#examples
 127 class UnicodeCSVWriter(object):
 128     """
 129     A CSV writer which will write rows to CSV file "f",
 130     which is encoded in the given encoding.
 131     """
 132
 133     def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
 134         # Redirect output to a queue
 135         self.queue = BytesIO()
 136         self.writer = csv.writer(self.queue, dialect=dialect, **kwds)
 137         self.stream = f
 138         self.encoder = codecs.getincrementalencoder(encoding)()
 139
 140     def writerow(self, row):
 141         self.writer.writerow([s.encode("utf-8") for s in row])
 142         # Fetch UTF-8 output from the queue ...
 143         data = self.queue.getvalue()
 144         data = data.decode("utf-8")
 145         # ... and reencode it into the target encoding
 146         data = self.encoder.encode(data)
 147         # write to the target stream
 148         self.stream.write(data)
 149         # empty queue
 150         self.queue.truncate(0)
 151
 152     def writerows(self, rows):
 153         for row in rows:
 154             self.writerow(row)
 155
 156
 157 # the original re.escape messes with unicode
 158 def re_escape(s):
 159     return re.sub(r"[(){}\[\].*?|^$\\+-]", r"\\\g<0>", s)
 160
 161
 162 BOT_BITS = ['bot', 'slurp', 'spider', 'facebook', 'crawler', 'parser', 'http']
 163
 164
 165 def is_crawler(request):
 166     user_agent = request.META.get('HTTP_USER_AGENT')
 167     if not user_agent:
 168         return True
 169     user_agent = user_agent.lower()
 170     return any(bot_bit in user_agent for bot_bit in BOT_BITS)
 171
 172
 173 def get_cached_render_key(instance, property_name, language=None):
 174     if language is None:
 175         language = get_language()
 176     return 'cached_render:%s.%s:%s:%s' % (
 177             type(instance).__name__,
 178             property_name,
 179             instance.pk,
 180             language
 181         )
 182
 183
 184 def cached_render(template_name, timeout=24 * 60 * 60):
 185     def decorator(method):
 186         @wraps(method)
 187         def wrapper(self):
 188             key = get_cached_render_key(self, method.__name__)
 189             content = cache.get(key)
 190             if content is None:
 191                 context = method(self)
 192                 content = render_to_string(template_name, context)
 193                 cache.set(key, str(content), timeout=timeout)
 194             else:
 195                 content = mark_safe(content)
 196             return content
 197         return wrapper
 198     return decorator
 199
 200
 201 def clear_cached_renders(bound_method):
 202     for lc, ln in settings.LANGUAGES:
 203         cache.delete(
 204             get_cached_render_key(
 205                 bound_method.__self__,
 206                 bound_method.__name__,
 207                 lc
 208             )
 209         )