feat: Enable reauthorization for Facebook (#1286)

app/models/channel/facebook_page.rb

@@ -19,6 +19,8 @@
 class Channel::FacebookPage < ApplicationRecord
   self.table_name = 'channel_facebook_pages'
 
+  include Reauthorizable
+
   validates :account_id, presence: true
   validates :page_id, uniqueness: { scope: :account_id }
   belongs_to :account

app/models/concerns/reauthorizable.rb

@@ -0,0 +1,57 @@
+# This concern is primarily targetted for business models dependant on external services
+# The auth tokens we obtained on their behalf could expire or becomes invalid.
+# We would be aware of it until we make the API call to the service and it throws error
+
+# Example:
+# when a user changes his/her password, the auth token they provided to chatwoot becomes invalid
+
+# This module helps to capture the errors into a counter and when threshold is passed would mark
+# the object to be reauthorized. We will also send an email to the owners alerting them of the error.
+
+# In the UI, we will check for the reauthorization_required? status and prompt the reauthorization flow
+
+module Reauthorizable
+  extend ActiveSupport::Concern
+
+  AUTHORIZATION_ERROR_THRESHOLD = 2
+
+  # model attribute
+  def reauthorization_required?
+    ::Redis::Alfred.get(reauthorization_required_key).present?
+  end
+
+  # model attribute
+  def authorization_error_count
+    ::Redis::Alfred.get(authorization_error_count_key).to_i
+  end
+
+  # action to be performed when we recieve authorization errors
+  # Implement in your exception handling logic for authorization errors
+  def authorization_error!
+    ::Redis::Alfred.incr(authorization_error_count_key)
+    prompt_reauthorization! if authorization_error_count >= AUTHORIZATION_ERROR_THRESHOLD
+  end
+
+  # Performed automatically if error threshold is breached
+  # could used to manually prompt reauthorization if auth scope changes
+  def prompt_reauthorization!
+    ::Redis::Alfred.set(reauthorization_required_key, true)
+    # TODO: send_reauthorize_prompt_email
+  end
+
+  # call this after you successfully Reauthorized the object in UI
+  def reauthorized!
+    ::Redis::Alfred.delete(authorization_error_count_key)
+    ::Redis::Alfred.delete(reauthorization_required_key)
+  end
+
+  private
+
+  def authorization_error_count_key
+    format(::Redis::Alfred::AUTHORIZATION_ERROR_COUNT, obj_type: self.class.table_name.singularize, obj_id: id)
+  end
+
+  def reauthorization_required_key
+    format(::Redis::Alfred::REAUTHORIZATION_REQUIRED, obj_type: self.class.table_name.singularize, obj_id: id)
+  end
+end