Infrastructure for caching avatars

Avatars now can be fetched server side and are cached on the server.

Issue #412
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/accounts/avatar.py

+# -*- coding: utf-8 -*-
+#
+# Copyright © 2012 - 2014 Michal Čihař <michal@cihar.com>
+#
+# This file is part of Weblate <http://weblate.org/>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import urllib2
+import urllib
+import hashlib
+import os.path
+from django.core.cache import get_cache, InvalidCacheBackendError
+from django.conf import settings
+
+import weblate
+from weblate import appsettings
+
+try:
+    import libravatar
+    HAS_LIBRAVATAR = True
+except ImportError:
+    HAS_LIBRAVATAR = False
+
+AVATAR_URL_PREFIX = getattr(
+    settings,
+    'AVATAR_URL_PREFIX',
+    'https://seccdn.libravatar.org/'
+)
+# See http://wiki.libravatar.org/api/
+# for available choices
+AVATAR_DEFAULT_IMAGE = getattr(
+    settings,
+    'AVATAR_DEFAULT_IMAGE',
+    'identicon'
+)
+
+PLURAL_SEPARATOR = '\x1e\x1e'
+
+
+def avatar_for_email(email, size=80):
+    '''
+    Generates url for avatar.
+    '''
+
+    # Safely handle blank email
+    if email == '':
+        email = 'noreply@weblate.org'
+
+    # Retrieve from cache
+    cache_key = 'avatar-%s-%s' % (email, size)
+    cache = get_cache('default')
+    url = cache.get(cache_key)
+    if url is not None:
+        return url
+
+    if HAS_LIBRAVATAR:
+        # Use libravatar library if available
+        url = libravatar.libravatar_url(
+            email=email,
+            https=True,
+            default=AVATAR_DEFAULT_IMAGE,
+            size=size
+        )
+
+    else:
+        # Fallback to standard method
+        mail_hash = hashlib.md5(email.lower()).hexdigest()
+
+        url = "%savatar/%s?" % (AVATAR_URL_PREFIX, mail_hash)
+
+        url += urllib.urlencode({
+            's': str(size),
+            'd': AVATAR_DEFAULT_IMAGE
+        })
+
+    # Store result in cache
+    cache.set(cache_key, url, 3600 * 24)
+
+    return url
+
+
+def get_avatar_image(user, size):
+    '''
+    Returns avatar image from cache (if available) or downloads it.
+    '''
+
+    cache_key = 'avatar-img-{0}-{1}'.format(
+        user.username,
+        size
+    )
+
+    # Try using avatar specific cache if available
+    try:
+        cache = get_cache('avatar')
+    except InvalidCacheBackendError:
+        cache = get_cache('default')
+
+    image = cache.get(cache_key)
+    if image is None:
+        try:
+            image = download_avatar_image(user, size)
+            cache.set(cache_key, image)
+        except IOError as error:
+            weblate.logger.error(
+                'Failed to fetch avatar for %s: %s',
+                user.username,
+                str(error)
+            )
+            fallback = os.path.join(
+                appsettings.WEB_ROOT,
+                'media/weblate-{0}.png'.format(size)
+            )
+            with open(fallback, 'r') as handle:
+                return handle.read()
+
+    return image
+
+
+def download_avatar_image(user, size):
+    '''
+    Downloads avatar image from remote server.
+    '''
+    url = avatar_for_email(user.email, size)
+    request = urllib2.Request(url)
+    request.timeout = 0.5
+    request.add_header('User-Agent', 'Weblate/%s' % weblate.VERSION)
+
+    # Fire request
+    handle = urllib2.urlopen(request)
+
+    # Read and possibly convert response
+    return handle.read()

weblate/accounts/views.py

@@ -19,6 +19,8 @@
 #
 
 from django.shortcuts import render, get_object_or_404, redirect
+from django.views.decorators.cache import cache_page
+from django.http import HttpResponse
 from django.contrib.auth import logout
 from django.conf import settings
 from django.contrib import messages
@@ -40,6 +42,7 @@ from social.apps.django_app.utils import BACKENDS
 from social.apps.django_app.views import complete
 
 import weblate
+from weblate.accounts.avatar import get_avatar_image
 from weblate.accounts.models import set_lang, remove_user, Profile
 from weblate.trans.models import Change, Project
 from weblate.accounts.forms import (
@@ -331,6 +334,19 @@ def user_page(request, user):
     )
 
 
+@cache_page(3600 * 24)
+def user_avatar(request, user, size):
+    '''
+    User avatar page.
+    '''
+    user = get_object_or_404(User, username=user)
+
+    return HttpResponse(
+        content_type='image/png',
+        content=get_avatar_image(user, size)
+    )
+
+
 def weblate_login(request):
     '''
     Login handler, just wrapper around login.

weblate/urls.py

@@ -631,11 +631,18 @@ urlpatterns = patterns(
 
     # User pages
     url(
-        r'^user/(?P<user>[^/]+)/',
+        r'^user/(?P<user>[^/]+)/$',
         'weblate.accounts.views.user_page',
         name='user_page',
     ),
 
+    # Avatars
+    url(
+        r'^user/(?P<user>[^/]+)/avatar/(?P<size>(32|128))/$',
+        'weblate.accounts.views.user_avatar',
+        name='user_avatar',
+    ),
+
     # Sitemap
     url(
         r'^sitemap\.xml$',