Rename site setting holiday calendar post id to topic id

config/locales/server.en.yml

@@ -1,3 +1,4 @@
 en:
   site_settings:
     discourse_simple_calendar_enabled: "Enable the discourse-simple-calendar feature. This will add support for a [calendar][/calendar] tag in the first post of a topic."
+    holiday_calendar_topic_id: "Topic ID of staffs holiday / absence calendar."

config/settings.yml

@@ -2,5 +2,5 @@ plugins:
   discourse_simple_calendar_enabled:
     default: true
     client: true
-  discourse_simple_calendar_holiday_post_id:
+  holiday_calendar_topic_id:
     default: ""

jobs/scheduled/update_holiday_usernames.rb

@@ -5,9 +5,10 @@ module Jobs
     PLUGIN_NAME ||= "discourse_simple_calendar".freeze
 
     def execute(args)
-      post_id = SiteSetting.discourse_simple_calendar_holiday_post_id
+      topic_id = SiteSetting.holiday_calendar_topic_id
+      return if topic_id.blank?
 
-      return if post_id.blank?
+      post_id = Post.find_by(topic_id: topic_id, post_number: 1)
 
       # Build a list of discourse users currently on holiday
       users_on_holiday = []

spec/jobs/update_holiday_usernames_spec.rb

@@ -9,7 +9,7 @@ describe DiscourseSimpleCalendar::UpdateHolidayUsernames do
       [/calendar]
     MD
     @topic = Fabricate(:topic, first_post: create_post(raw: raw))
-    SiteSetting.discourse_simple_calendar_holiday_post_id = @topic.first_post.id
+    SiteSetting.holiday_calendar_topic_id = @topic.id
   end
 
   it "should update users on holiday list" do