Add env variable support for number of followable hashtags in feed column (#2500)

* Add env variable support for number of followable hashtags in feed column.

* Add a note about performance concerns for higher values.

See discussion in https://github.com/glitch-soc/mastodon/pull/2500

* Update .devcontainer/docker-compose.yml

---------

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

.env.production.sample

@@ -251,6 +251,11 @@ SMTP_FROM_ADDRESS=notifications@example.com
 # Maximum allowed character count
 MAX_TOOT_CHARS=500
 
+# Maximum allowed hashtags to follow in a feed column
+# Note that setting this value higher may cause significant
+# database load
+MAX_FEED_HASHTAGS=4
+
 # Maximum number of pinned posts
 MAX_PINNED_TOOTS=5
 

app/javascript/flavours/glitch/features/hashtag_timeline/components/column_settings.jsx

@@ -9,6 +9,8 @@ import { NonceProvider } from 'react-select';
 import AsyncSelect from 'react-select/async';
 import Toggle from 'react-toggle';
 
+import { maxFeedHashtags } from 'flavours/glitch/initial_state';
+
 import SettingToggle from '../../notifications/components/setting_toggle';
 
 const messages = defineMessages({
@@ -46,9 +48,9 @@ class ColumnSettings extends PureComponent {
   onSelect = mode => value => {
     const oldValue = this.tags(mode);
 
-    // Prevent changes that add more than 4 tags, but allow removing
-    // tags that were already added before
-    if ((value.length > 4) && !(value < oldValue)) {
+    // Prevent changes that add more than the number of configured
+    // tags, but allow removing tags that were already added before
+    if ((value.length > maxFeedHashtags) && !(value < oldValue)) {
       return;
     }
 

app/javascript/flavours/glitch/initial_state.js

@@ -67,6 +67,7 @@ export const hasMultiColumnPath = initialPath === '/'
  * @property {InitialStateMeta} meta
  * @property {object} local_settings
  * @property {number} max_toot_chars
+ * @property {number} max_feed_hashtags
  * @property {number} poll_limits
  */
 
@@ -130,6 +131,7 @@ export const sso_redirect = getMeta('sso_redirect');
 
 // Glitch-soc-specific settings
 export const maxChars = (initialState && initialState.max_toot_chars) || 500;
+export const maxFeedHashtags = (initialState && initialState.max_feed_hashtags) || 4;
 export const favouriteModal = getMeta('favourite_modal');
 export const pollLimits = (initialState && initialState.poll_limits);
 export const defaultContentType = getMeta('default_content_type');

app/models/tag_feed.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class TagFeed < PublicFeed
-  LIMIT_PER_MODE = 4
+  LIMIT_PER_MODE = (ENV['MAX_FEED_HASHTAGS'] || 4).to_i
 
   # @param [Tag] tag
   # @param [Account] account

app/serializers/initial_state_serializer.rb

@@ -5,7 +5,7 @@ class InitialStateSerializer < ActiveModel::Serializer
 
   attributes :meta, :compose, :accounts,
              :media_attachments, :settings,
-             :max_toot_chars, :poll_limits,
+             :max_toot_chars, :max_feed_hashtags, :poll_limits,
              :languages
 
   attribute :critical_updates_pending, if: -> { object&.role&.can?(:view_devops) && SoftwareUpdate.check_enabled? }
@@ -17,6 +17,10 @@ class InitialStateSerializer < ActiveModel::Serializer
     StatusLengthValidator::MAX_CHARS
   end
 
+  def max_feed_hashtags
+    TagFeed::LIMIT_PER_MODE
+  end
+
   def poll_limits
     {
       max_options: PollValidator::MAX_OPTIONS,