Create quarantined subreddits content gate

When a user visits a quarantined subreddit for the first time, they are
presented with a content gate so that they can choose to optin to view
the subreddit's content. This preference is remembered per subreddit.
If a user is logged out, it requires the user to log in before validating
that the user has chosen to opt in to view the subreddit.

r2/r2/config/routing.py

@@ -70,6 +70,7 @@ def make_map():
     mc('/submit', controller='front', action='submit')
 
     mc('/over18', controller='post', action='over18')
+    mc('/quarantine', controller='post', action='quarantine')
 
     mc('/rules', controller='front', action='rules')
     mc('/sup', controller='front', action='sup')

r2/r2/controllers/post.py

@@ -81,6 +81,16 @@ class PostController(ApiController):
         return BoringPage(_("over 18?"), content=Over18(),
                           show_sidebar=False).render()
 
+    @validate(
+        dest=VDestination(default='/'),
+    )
+    def GET_quarantine(self, dest):
+        sr = UrlParser(dest).get_subreddit()
+        return BoringPage(_("opt in to potentially offensive content?"),
+            content=Quarantine(sr.name),
+            show_sidebar=False,
+        ).render()
+
     @validate(VModhash(fatal=False),
               over18 = nop('over18'),
               dest = VDestination(default = '/'))
@@ -100,6 +110,23 @@ class PostController(ApiController):
                 delete_over18_cookie()
             return self.redirect('/')
 
+    @validate(
+        VModhash(),
+        sr=VSRByName('sr_name'),
+        accept=VBoolean('accept'),
+        dest=VDestination(default='/'),
+    )
+    def POST_quarantine(self, sr, accept, dest):
+        if not c.user_is_loggedin:
+            return self.redirect(dest)
+
+        if accept:
+            QuarantinedSubredditOptInsByAccount.opt_in(c.user, sr)
+            return self.redirect(dest)
+        else:
+            QuarantinedSubredditOptInsByAccount.opt_out(c.user, sr)
+            return self.redirect('/')
+
     @csrf_exempt
     @validate(msg_hash = nop('x'))
     def POST_optout(self, msg_hash):

r2/r2/controllers/reddit_base.py

@@ -1668,13 +1668,11 @@ class RedditController(OAuth2ResourceController):
                     # do not leak the existence of multis via 403.
                     self.abort404()
                 elif not c.site.is_exposed(c.user):
-                    errpage = pages.RedditError(
-                        strings.quarantine_subreddit_title,
-                        strings.quarantine_subreddit_message,
-                        image="subreddit-banned.png",
-                    )
-                    request.environ['usable_error_content'] = errpage.render()
-                    self.abort403()
+                    if not c.user_is_loggedin:
+                        return self.intermediate_redirect('/login', sr_path=False)
+                    else:
+                        return self.intermediate_redirect("/quarantine", sr_path=False)
+
                 elif c.site.type == 'gold_only' and not (c.user.gold or c.user.gold_charter):
                     public_description = c.site.public_description
                     errpage = pages.RedditError(

r2/r2/lib/pages/pages.py

@@ -2457,6 +2457,13 @@ class Over18(Templated):
     """The creepy 'over 18' check page for nsfw content."""
     pass
 
+
+class Quarantine(Templated):
+    """The opt in page for viewing quarantined content."""
+    def __init__(self, sr_name):
+        Templated.__init__(self, sr_name=sr_name)
+
+
 class SubredditTopBar(CachedTemplate):
 
     """The horizontal strip at the top of most pages for navigating

r2/r2/models/account.py

@@ -1076,3 +1076,33 @@ class SubredditParticipationByAccount(tdb_cassandra.DenormalizedRelation):
     @classmethod
     def mark_participated(cls, account, subreddit):
         cls.create(account, [subreddit])
+
+
+class QuarantinedSubredditOptInsByAccount(tdb_cassandra.DenormalizedRelation):
+    _use_db = True
+    _last_modified_name = 'QuarantineSubredditOptin'
+    _read_consistency_level = tdb_cassandra.CL.QUORUM
+    _write_consistency_level = tdb_cassandra.CL.QUORUM
+    _connection_pool = 'main'
+    _views = []
+
+    @classmethod
+    def value_for(cls, thing1, thing2):
+        return datetime.now(g.tz)
+
+    @classmethod
+    def opt_in(cls, account, subreddit):
+        if subreddit.quarantine:
+            cls.create(account, subreddit)
+
+    @classmethod
+    def opt_out(cls, account, subreddit):
+        cls.destroy(account, subreddit)
+
+    @classmethod
+    def is_opted_in(cls, user, subreddit):
+        try:
+            r = cls.fast_query(user, [subreddit])
+        except tdb_cassandra.NotFound:
+            return False
+        return (user, subreddit) in r

r2/r2/models/subreddit.py

@@ -37,7 +37,12 @@ from pylons import c, g, request
 from pylons.i18n import _, N_
 
 from r2.lib.db.thing import Thing, Relation, NotFound
-from account import Account, AccountsActiveBySR, FakeAccount
+from account import (
+    Account,
+    AccountsActiveBySR,
+    FakeAccount,
+    QuarantinedSubredditOptInsByAccount,
+)
 from printable import Printable
 from r2.lib.db.userrel import UserRel, MigratingUserRel
 from r2.lib.db.operators import lower, or_, and_, not_, desc
@@ -793,7 +798,7 @@ class Subreddit(Thing, Printable, BaseSite):
     def can_view(self, user):
         if c.user_is_admin:
             return True
-        
+
         if self.spammy() or not self.is_exposed(user):
             return False
         elif self.type in ('public', 'restricted',
@@ -811,9 +816,15 @@ class Subreddit(Thing, Printable, BaseSite):
                     self.is_moderator_invite(user))
 
     def is_exposed(self, user):
-        """Checks if visible to user based on the quarantine attribute."""
-        return not self.quarantine or (c.user_is_loggedin and 
-                                       self.is_subscriber(user))
+        if c.user_is_admin:
+            return True
+        elif not self.quarantine:
+            return True
+        elif (c.user_is_loggedin and
+                QuarantinedSubredditOptInsByAccount.is_opted_in(user, self)):
+            return True
+
+        return False
 
     def can_demod(self, bully, victim):
         bully_rel = self.get_moderator(bully)

r2/r2/templates/quarantine.html

@@ -0,0 +1,44 @@
+## The contents of this file are subject to the Common Public Attribution
+## License Version 1.0. (the "License"); you may not use this file except in
+## compliance with the License. You may obtain a copy of the License at
+## http://code.reddit.com/LICENSE. The License is based on the Mozilla Public
+## License Version 1.1, but Sections 14 and 15 have been added to cover use of
+## software over a computer network and provide for limited attribution for the
+## Original Developer. In addition, Exhibit A has been modified to be
+## consistent with Exhibit B.
+##
+## Software distributed under the License is distributed on an "AS IS" basis,
+## WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
+## the specific language governing rights and limitations under the License.
+##
+## The Original Code is reddit.
+##
+## The Original Developer is the Initial Developer.  The Initial Developer of
+## the Original Code is reddit Inc.
+##
+## All portions of the code written by reddit are Copyright (c) 2006-2015
+## reddit Inc. All Rights Reserved.
+###############################################################################
+
+<% from r2.lib.template_helpers import static %>
+
+<div class="content over18" style="text-align: center">
+  <p class="error">
+    ${_("the following content is questionable")}
+  </p>
+  <img src="${static('over18.png')}" alt="" height="254" width="180" />
+  
+  <form method="post" action="" class="pretty-form"
+      ${"target='_top'" if c.cname else ""}>
+    <input type="hidden" name="uh" value="${c.modhash}" />
+    <input type="hidden" name="sr_name" value="${thing.sr_name}" />
+    <p>
+      ${_("are you willing to see this questionable content?")}
+    </p>
+    <p>
+      <button type="submit" name="accept" value="yes">yes</button>
+      <button type="submit" name="accept" value="no">no</button>
+    </p>
+  </form>
+</div>
+