Chore: Convert Message Sender to polymorphic (#740)

Fixes #680

app/models/agent_bot.rb

@@ -17,12 +17,13 @@ class AgentBot < ApplicationRecord
 
   has_many :agent_bot_inboxes, dependent: :destroy
   has_many :inboxes, through: :agent_bot_inboxes
+  has_many :messages, as: :sender, dependent: :restrict_with_exception
 
-  def push_event_data
+  def push_event_data(inbox = nil)
     {
       id: id,
       name: name,
-      avatar_url: avatar_url,
+      avatar_url: avatar_url || inbox&.avatar_url,
       type: 'agent_bot'
     }
   end

app/models/contact.rb

@@ -35,7 +35,7 @@ class Contact < ApplicationRecord
   has_many :conversations, dependent: :destroy
   has_many :contact_inboxes, dependent: :destroy
   has_many :inboxes, through: :contact_inboxes
-  has_many :messages, dependent: :destroy
+  has_many :messages, as: :sender, dependent: :destroy
 
   before_validation :downcase_email
   after_create_commit :dispatch_create_event

app/models/message.rb

@@ -8,28 +8,23 @@
 #  content_type       :integer          default("text")
 #  message_type       :integer          not null
 #  private            :boolean          default(FALSE)
+#  sender_type        :string
 #  status             :integer          default("sent")
 #  created_at         :datetime         not null
 #  updated_at         :datetime         not null
 #  account_id         :integer          not null
-#  contact_id         :bigint
 #  conversation_id    :integer          not null
 #  inbox_id           :integer          not null
+#  sender_id          :bigint
 #  source_id          :string
-#  user_id            :integer
 #
 # Indexes
 #
-#  index_messages_on_account_id       (account_id)
-#  index_messages_on_contact_id       (contact_id)
-#  index_messages_on_conversation_id  (conversation_id)
-#  index_messages_on_inbox_id         (inbox_id)
-#  index_messages_on_source_id        (source_id)
-#  index_messages_on_user_id          (user_id)
-#
-# Foreign Keys
-#
-#  fk_rails_...  (contact_id => contacts.id)
+#  index_messages_on_account_id                 (account_id)
+#  index_messages_on_conversation_id            (conversation_id)
+#  index_messages_on_inbox_id                   (inbox_id)
+#  index_messages_on_sender_type_and_sender_id  (sender_type,sender_id)
+#  index_messages_on_source_id                  (source_id)
 #
 
 class Message < ApplicationRecord
@@ -65,8 +60,11 @@ class Message < ApplicationRecord
   belongs_to :account
   belongs_to :inbox
   belongs_to :conversation, touch: true
+
+  # FIXME: phase out user and contact after 1.4 since the info is there in sender
   belongs_to :user, required: false
   belongs_to :contact, required: false
+  belongs_to :sender, polymorphic: true, required: false
 
   has_many :attachments, dependent: :destroy, autosave: true, before_add: :validate_attachments_limit
 
@@ -88,7 +86,8 @@ class Message < ApplicationRecord
       conversation_id: conversation.display_id
     )
     data.merge!(attachments: attachments.map(&:push_event_data)) if attachments.present?
-    data.merge!(sender: user.push_event_data) if user
+    data.merge!(sender: sender.push_event_data) if sender && !sender.is_a?(AgentBot)
+    data.merge!(sender: sender.push_event_data(inbox)) if sender&.is_a?(AgentBot)
     data
   end
 
@@ -105,8 +104,7 @@ class Message < ApplicationRecord
       content_type: content_type,
       content_attributes: content_attributes,
       source_id: source_id,
-      sender: user.try(:webhook_data),
-      contact: contact.try(:webhook_data),
+      sender: sender.try(:webhook_data),
       inbox: inbox.webhook_data,
       conversation: conversation.webhook_data,
       account: account.webhook_data

app/models/user.rb

@@ -65,7 +65,7 @@ class User < ApplicationRecord
   has_many :assigned_conversations, foreign_key: 'assignee_id', class_name: 'Conversation', dependent: :nullify
   has_many :inbox_members, dependent: :destroy
   has_many :inboxes, through: :inbox_members, source: :inbox
-  has_many :messages
+  has_many :messages, as: :sender
   has_many :invitees, through: :account_users, class_name: 'User', foreign_key: 'inviter_id', dependent: :nullify
 
   has_many :notifications, dependent: :destroy