Change auto-following admin-selected accounts, show in recommendations (#16078)

app/models/account_suggestions/past_interactions_source.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+class AccountSuggestions::PastInteractionsSource < AccountSuggestions::Source
+  include Redisable
+
+  def key
+    :past_interactions
+  end
+
+  def get(account, skip_account_ids: [], limit: 40)
+    account_ids = account_ids_for_account(account.id, limit + skip_account_ids.size) - skip_account_ids
+
+    as_ordered_suggestions(
+      scope.where(id: account_ids),
+      account_ids
+    ).take(limit)
+  end
+
+  def remove(account, target_account_id)
+    redis.zrem("interactions:#{account.id}", target_account_id)
+  end
+
+  private
+
+  def scope
+    Account.searchable
+  end
+
+  def account_ids_for_account(account_id, limit)
+    redis.zrevrange("interactions:#{account_id}", 0, limit).map(&:to_i)
+  end
+
+  def to_ordered_list_key(account)
+    account.id
+  end
+end