FEATURE: Allow tutorials to declare prerequisite before it starts.

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/advanced_user_narrative.rb

@@ -74,7 +74,7 @@ module DiscourseNarrativeBot
           action: :reply_to_topic_notification_level_changed
         },
         reply: {
-          next_state: :tutorial_notification_level,
+          next_state: :tutorial_change_topic_notification_level,
           action: :missing_topic_notification_level_change
         }
       },

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/base.rb

@@ -19,6 +19,21 @@ module DiscourseNarrativeBot
 
         begin
           opts = transition
+
+          loop do
+            next_state = opts[:next_state]
+
+            break if next_state == :end
+
+            next_opts = self.class::TRANSITION_TABLE.fetch(next_state)
+            prerequisite = next_opts[:prerequisite]
+
+            break if !prerequisite || instance_eval(&prerequisite)
+
+            [:next_state, :next_instructions].each do |key|
+              opts[key] = next_opts[key]
+            end
+          end
         rescue InvalidTransitionError
           # For given input, no transition for current state
           return

plugins/discourse-narrative-bot/lib/discourse_narrative_bot/new_user_narrative.rb

@@ -38,6 +38,7 @@ module DiscourseNarrativeBot
       },
 
       tutorial_emoji: {
+        prerequisite: Proc.new { SiteSetting.enable_emoji },
         next_state: :tutorial_mention,
         next_instructions: Proc.new {
           I18n.t("#{I18N_KEY}.mention.instructions",