feat: Auto resolve conversations after n days of inactivity (#1308)

fixes: #418

app/models/conversation.rb

@@ -54,11 +54,13 @@ class Conversation < ApplicationRecord
   # wanted to change this to after_update commit. But it ended up creating a loop
   # reinvestigate in future and identity the implications
   after_update :notify_status_change, :create_activity
-  after_create_commit :notify_conversation_creation
+  after_create_commit :notify_conversation_creation, :queue_conversation_auto_resolution_job
   after_save :run_round_robin
 
   acts_as_taggable_on :labels
 
+  delegate :auto_resolve_duration, to: :account
+
   def can_reply?
     return true unless inbox&.channel&.has_24_hour_messaging_window?
 
@@ -145,6 +147,12 @@ class Conversation < ApplicationRecord
     dispatcher_dispatch(CONVERSATION_CREATED)
   end
 
+  def queue_conversation_auto_resolution_job
+    return unless auto_resolve_duration
+
+    AutoResolveConversationsJob.set(wait_until: (last_activity_at || created_at) + auto_resolve_duration.days).perform_later(id)
+  end
+
   def self_assign?(assignee_id)
     assignee_id.present? && Current.user&.id == assignee_id
   end
@@ -157,15 +165,17 @@ class Conversation < ApplicationRecord
   end
 
   def create_activity
-    return unless Current.user
-
-    user_name = Current.user.name
-
-    create_status_change_message(user_name) if saved_change_to_status?
+    user_name = Current.user.name if Current.user.present?
+    status_change_activity(user_name) if saved_change_to_status?
     create_assignee_change(user_name) if saved_change_to_assignee_id?
     create_label_change(user_name) if saved_change_to_label_list?
   end
 
+  def status_change_activity(user_name)
+    create_status_change_message(user_name)
+    queue_conversation_auto_resolution_job if open?
+  end
+
   def activity_message_params(content)
     { account_id: account_id, inbox_id: inbox_id, message_type: :activity, content: content }
   end
@@ -210,12 +220,18 @@ class Conversation < ApplicationRecord
   end
 
   def create_status_change_message(user_name)
-    content = I18n.t("conversations.activity.status.#{status}", user_name: user_name)
+    content = if user_name
+                I18n.t("conversations.activity.status.#{status}", user_name: user_name)
+              elsif resolved?
+                I18n.t('conversations.activity.status.auto_resolved', duration: auto_resolve_duration)
+              end
 
-    messages.create(activity_message_params(content))
+    messages.create(activity_message_params(content)) if content
   end
 
   def create_assignee_change(user_name)
+    return unless user_name
+
     params = { assignee_name: assignee.name, user_name: user_name }.compact
     key = assignee_id ? 'assigned' : 'removed'
     key = 'self_assigned' if self_assign? assignee_id
@@ -225,6 +241,8 @@ class Conversation < ApplicationRecord
   end
 
   def create_label_change(user_name)
+    return unless user_name
+
     previous_labels, current_labels = previous_changes[:label_list]
     return unless (previous_labels.is_a? Array) && (current_labels.is_a? Array)