feed: make /feed API call configurable server and client-side

On server-side, this can be enabled by providing a base URL to use to
build the full URL. Limit also becomes configurable. On client-side,
we need to add a switch to know whatever or not the additional link
can be displayed.

docs/docs/configuration/client.rst

@@ -20,7 +20,8 @@ preferably in the script tag which embeds the JS:
             data-isso-avatar-bg="#f0f0f0"
             data-isso-avatar-fg="#9abf88 #5698c4 #e279a3 #9163b6 ..."
             data-isso-vote="true"
-            data-vote-levels=""
+            data-isso-vote-levels=""
+            data-isso-feed="false"
             src="/prefix/js/embed.js"></script>
 
 Furthermore you can override the automatic title detection inside
@@ -125,3 +126,10 @@ For example, the value `"-5,5"` will cause each `isso-comment` to be given one o
 - `isso-vote-level-2` for scores of `5` and greater
 
 These classes can then be used to customize the appearance of comments (eg. put a star on popular comments)
+
+data-isso-feed
+--------------
+
+Enable or disable the addition of a link to the feed for the comment
+thread. The link will only be valid if the appropriate setting, in
+``[rss]`` section, is also enabled server-side.

docs/docs/configuration/server.rst

@@ -308,6 +308,27 @@ algorithm
     Arguments have to be in that order, but can be reduced to `pbkdf2:4096`
     for example to override the iterations only.
 
+.. _configure-rss:
+
+RSS
+---
+
+Isso can provide an Atom feed for each comment thread. Users can use
+them to subscribe to comments and be notified of changes. Atom feeds
+are enabled as soon as there is a base URL defined in this section.
+
+.. code-block:: ini
+
+    [rss]
+    base =
+    limit = 100
+
+base
+    base URL to use to build complete URI to pages (by appending the URI from Isso)
+
+limit
+    number of most recent comments to return for a thread
+
 Appendum
 --------
 

isso/js/app/config.js

@@ -15,7 +15,8 @@ define(function() {
         "avatar-fg": ["#9abf88", "#5698c4", "#e279a3", "#9163b6",
                       "#be5168", "#f19670", "#e4bf80", "#447c69"].join(" "),
         "vote": true,
-        "vote-levels": null
+        "vote-levels": null,
+        "feed": false
     };
 
     var js = document.getElementsByTagName("script");

isso/js/embed.js

@@ -27,11 +27,13 @@ require(["app/lib/ready", "app/config", "app/i18n", "app/api", "app/isso", "app/
             return console.log("abort, #isso-thread is missing");
         }
 
+        if (config["feed"]) {
             var feedLink = $.new('a', i18n.translate('atom-feed'));
             var feedLinkWrapper = $.new('span.isso-feedlink');
             feedLink.href = api.feed($("#isso-thread").getAttribute("data-isso-id"));
             feedLinkWrapper.append(feedLink);
             $("#isso-thread").append(feedLinkWrapper);
+        }
         $("#isso-thread").append($.new('h4'));
         $("#isso-thread").append(new isso.Postbox(null));
         $("#isso-thread").append('<div id="isso-root"></div>');

isso/tests/test_comments.py

@@ -31,9 +31,9 @@ class TestComments(unittest.TestCase):
         fd, self.path = tempfile.mkstemp()
         conf = config.load(os.path.join(dist.location, "share", "isso.conf"))
         conf.set("general", "dbpath", self.path)
-        conf.set("general", "host", "https://example.org")
         conf.set("guard", "enabled", "off")
         conf.set("hash", "algorithm", "none")
+        self.conf = conf
 
         class App(Isso, core.Mixin):
             pass
@@ -326,7 +326,13 @@ class TestComments(unittest.TestCase):
 
         self.assertListEqual(list(rv.keys()), [])
 
+    def testNoFeed(self):
+        rv = self.get('/feed?uri=%2Fpath%2Fnothing')
+        self.assertEqual(rv.status_code, 404)
+
     def testFeedEmpty(self):
+        self.conf.set("rss", "base", "https://example.org")
+
         rv = self.get('/feed?uri=%2Fpath%2Fnothing')
         self.assertEqual(rv.status_code, 200)
         self.assertEqual(rv.headers['ETag'], '"empty"')
@@ -335,6 +341,8 @@ class TestComments(unittest.TestCase):
 <feed xmlns="http://www.w3.org/2005/Atom" xmlns:thr="http://purl.org/syndication/thread/1.0"><updated>1970-01-01T01:00:00Z</updated><id>tag:example.org,2018:/isso/thread/path/nothing</id><title>Comments for example.org/path/nothing</title></feed>""")
 
     def testFeed(self):
+        self.conf.set("rss", "base", "https://example.org")
+
         self.post('/new?uri=%2Fpath%2F', data=json.dumps({'text': 'First'}))
         self.post('/new?uri=%2Fpath%2F',
                   data=json.dumps({'text': 'First', 'parent': 1}))

isso/views/comments.py

@@ -854,11 +854,15 @@ class API(object):
     """
     @requires(str, 'uri')
     def feed(self, environ, request, uri):
+        conf = self.isso.conf.section("rss")
+        if not conf.get('base'):
+            raise NotFound
+
         args = {
             'uri': uri,
             'order_by': 'id',
             'asc': 0,
-            'limit': 100
+            'limit': conf.getint('limit')
         }
         try:
             args['limit'] = max(int(request.args.get('limit')), args['limit'])
@@ -867,7 +871,7 @@ class API(object):
         except ValueError:
             return BadRequest("limit should be integer")
         comments = self.comments.fetch(**args)
-        base = self.conf.get('host').split()[0]
+        base = conf.get('base')
         hostname = urlparse(base).netloc
 
         # Let's build an Atom feed.

share/isso.conf

@@ -180,3 +180,15 @@ salt = Eech7co8Ohloopo9Ol6baimi
 # strengthening. Arguments have to be in that order, but can be reduced to
 # pbkdf2:4096 for example to override the iterations only.
 algorithm = pbkdf2
+
+
+[rss]
+# Provide an Atom feed for each comment thread for users to subscribe to.
+
+# The base URL of pages is needed to build the Atom feed. By appending
+# the URI, we should get the complete URL to use to access the page
+# with the comments. When empty, Atom feeds are disabled.
+base =
+
+# Limit the number of elements to return for each thread.
+limit = 100