Fix follow suggestions potentially including silenced or blocked accounts (#29306)

app/models/account_suggestions/friends_of_friends_source.rb

@@ -2,31 +2,15 @@
 
 class AccountSuggestions::FriendsOfFriendsSource < AccountSuggestions::Source
   def get(account, limit: DEFAULT_LIMIT)
-    Account.find_by_sql([<<~SQL.squish, { id: account.id, limit: limit }]).map { |row| [row.id, key] }
-      WITH first_degree AS (
-          SELECT target_account_id
-          FROM follows
-          JOIN accounts AS target_accounts ON follows.target_account_id = target_accounts.id
-          WHERE account_id = :id
-            AND NOT target_accounts.hide_collections
-      )
-      SELECT accounts.id, COUNT(*) AS frequency
-      FROM accounts
-      JOIN follows ON follows.target_account_id = accounts.id
-      JOIN account_stats ON account_stats.account_id = accounts.id
-      LEFT OUTER JOIN follow_recommendation_mutes ON follow_recommendation_mutes.target_account_id = accounts.id AND follow_recommendation_mutes.account_id = :id
-      WHERE follows.account_id IN (SELECT * FROM first_degree)
-        AND NOT EXISTS (SELECT 1 FROM follows f WHERE f.target_account_id = follows.target_account_id AND f.account_id = :id)
-        AND follows.target_account_id <> :id
-        AND accounts.discoverable
-        AND accounts.suspended_at IS NULL
-        AND accounts.silenced_at IS NULL
-        AND accounts.moved_to_account_id IS NULL
-        AND follow_recommendation_mutes.target_account_id IS NULL
-      GROUP BY accounts.id, account_stats.id
-      ORDER BY frequency DESC, account_stats.followers_count ASC
-      LIMIT :limit
-    SQL
+    first_degree = account.following.where.not(hide_collections: true).select(:id).reorder(nil)
+    base_account_scope(account)
+      .joins(:account_stat)
+      .where(id: Follow.where(account_id: first_degree).select(:target_account_id))
+      .group('accounts.id, account_stats.id')
+      .reorder('frequency DESC, followers_count DESC')
+      .limit(limit)
+      .pluck(Arel.sql('accounts.id, COUNT(*) AS frequency'))
+      .map { |id, _frequency| [id, key] }
   end
 
   private

app/models/account_suggestions/similar_profiles_source.rb

@@ -51,7 +51,8 @@ class AccountSuggestions::SimilarProfilesSource < AccountSuggestions::Source
     recently_followed_account_ids = account.active_relationships.recent.limit(5).pluck(:target_account_id)
 
     if Chewy.enabled? && !recently_followed_account_ids.empty?
-      QueryBuilder.new(recently_followed_account_ids, account).build.limit(limit).hits.pluck('_id').map(&:to_i).zip([key].cycle)
+      ids_from_es = QueryBuilder.new(recently_followed_account_ids, account).build.limit(limit).hits.pluck('_id').map(&:to_i)
+      base_account_scope(account).where(id: ids_from_es).pluck(:id).zip([key].cycle)
     else
       []
     end

app/models/account_suggestions/source.rb

@@ -12,6 +12,8 @@ class AccountSuggestions::Source
   def base_account_scope(account)
     Account
       .searchable
+      .where(discoverable: true)
+      .without_silenced
       .where.not(follows_sql, id: account.id)
       .where.not(follow_requests_sql, id: account.id)
       .not_excluded_by_account(account)

spec/models/account_suggestions/friends_of_friends_source_spec.rb

@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe AccountSuggestions::FriendsOfFriendsSource do
+  describe '#get' do
+    subject { described_class.new }
+
+    let!(:bob) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:alice) { Fabricate(:account, discoverable: true, hide_collections: true) }
+    let!(:eve) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:mallory) { Fabricate(:account, discoverable: false, hide_collections: false) }
+    let!(:eugen) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:john) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:jerk) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:neil) { Fabricate(:account, discoverable: true, hide_collections: false) }
+    let!(:larry) { Fabricate(:account, discoverable: true, hide_collections: false) }
+
+    context 'with follows and blocks' do
+      before do
+        bob.block!(jerk)
+        FollowRecommendationMute.create!(account: bob, target_account: neil)
+
+        # bob follows eugen, alice and larry
+        [eugen, alice, larry].each { |account| bob.follow!(account) }
+
+        # alice follows eve and mallory
+        [john, mallory].each { |account| alice.follow!(account) }
+
+        # eugen follows eve, john, jerk, larry and neil
+        [eve, mallory, jerk, larry, neil].each { |account| eugen.follow!(account) }
+      end
+
+      it 'returns eligible accounts', :aggregate_failures do
+        results = subject.get(bob)
+
+        # eve is returned through eugen
+        expect(results).to include([eve.id, :friends_of_friends])
+
+        # john is not reachable because alice hides who she follows
+        expect(results).to_not include([john.id, :friends_of_friends])
+
+        # mallory is not discoverable
+        expect(results).to_not include([mallory.id, :friends_of_friends])
+
+        # larry is not included because he's followed already
+        expect(results).to_not include([larry.id, :friends_of_friends])
+
+        # jerk is blocked
+        expect(results).to_not include([jerk.id, :friends_of_friends])
+
+        # the suggestion for neil has already been rejected
+        expect(results).to_not include([neil.id, :friends_of_friends])
+      end
+    end
+
+    context 'with deterministic order' do
+      before do
+        # bob follows eve and mallory
+        [eve, mallory].each { |account| bob.follow!(account) }
+
+        # eve follows eugen, john, and jerk
+        [jerk, eugen, john].each { |account| eve.follow!(account) }
+
+        # mallory follows eugen, john, and neil
+        [neil, eugen, john].each { |account| mallory.follow!(account) }
+
+        john.follow!(eugen)
+        john.follow!(neil)
+      end
+
+      it 'returns eligible accounts in the expected order' do
+        expect(subject.get(bob)).to eq [
+          [eugen.id, :friends_of_friends], # followed by 2 friends, 3 followers total
+          [john.id, :friends_of_friends], # followed by 2 friends, 2 followers total
+          [neil.id, :friends_of_friends], # followed by 1 friend, 2 followers total
+          [jerk.id, :friends_of_friends], # followed by 1 friend, 1 follower total
+        ]
+      end
+    end
+  end
+end

spec/models/account_suggestions/source_spec.rb

@@ -11,14 +11,16 @@ RSpec.describe AccountSuggestions::Source do
     end
 
     context 'with follows and follow requests' do
-      let!(:account_domain_blocked_account) { Fabricate(:account, domain: 'blocked.host') }
-      let!(:account) { Fabricate(:account) }
-      let!(:blocked_account) { Fabricate(:account) }
-      let!(:eligible_account) { Fabricate(:account) }
-      let!(:follow_recommendation_muted_account) { Fabricate(:account) }
-      let!(:follow_requested_account) { Fabricate(:account) }
-      let!(:following_account) { Fabricate(:account) }
-      let!(:moved_account) { Fabricate(:account, moved_to_account: Fabricate(:account)) }
+      let!(:account_domain_blocked_account) { Fabricate(:account, domain: 'blocked.host', discoverable: true) }
+      let!(:account) { Fabricate(:account, discoverable: true) }
+      let!(:blocked_account) { Fabricate(:account, discoverable: true) }
+      let!(:eligible_account) { Fabricate(:account, discoverable: true) }
+      let!(:follow_recommendation_muted_account) { Fabricate(:account, discoverable: true) }
+      let!(:follow_requested_account) { Fabricate(:account, discoverable: true) }
+      let!(:following_account) { Fabricate(:account, discoverable: true) }
+      let!(:moved_account) { Fabricate(:account, moved_to_account: Fabricate(:account), discoverable: true) }
+      let!(:silenced_account) { Fabricate(:account, silenced: true, discoverable: true) }
+      let!(:undiscoverable_account) { Fabricate(:account, discoverable: false) }
 
       before do
         Fabricate :account_domain_block, account: account, domain: account_domain_blocked_account.domain
@@ -40,6 +42,8 @@ RSpec.describe AccountSuggestions::Source do
           .and not_include(follow_requested_account)
           .and not_include(following_account)
           .and not_include(moved_account)
+          .and not_include(silenced_account)
+          .and not_include(undiscoverable_account)
       end
     end
   end