Feature: User Notification Objects (#752)

Co-authored-by: Pranav Raj S <pranavrajs@gmail.com>

db/migrate/20200422130153_create_notifications.rb

@@ -0,0 +1,34 @@
+class CreateNotifications < ActiveRecord::Migration[6.0]
+  def change
+    create_table :notifications do |t|
+      t.references :account, index: true, null: false
+      t.references :user, index: true, null: false
+      t.integer :notification_type, null: false
+      t.references :primary_actor, polymorphic: true, null: false, index: { name: 'uniq_primary_actor_per_account_notifications' }
+      t.references :secondary_actor, polymorphic: true, index: { name: 'uniq_secondary_actor_per_account_notifications' }
+      t.timestamp :read_at, default: nil
+
+      t.timestamps
+    end
+
+    create_table :notification_subscriptions do |t|
+      t.references :user, index: true, null: false
+      t.integer :subscription_type, null: false
+      t.jsonb :subscription_attributes, null: false, default: '{}'
+      t.timestamps
+    end
+
+    add_column :notification_settings, :push_flags, :integer, default: 0, null: false
+    add_push_settings_to_users
+  end
+
+  def add_push_settings_to_users
+    ::User.find_in_batches do |users_batch|
+      users_batch.each do |user|
+        user_notification_setting = user.notification_settings
+        user_notification_setting.push_conversation_assignment = true
+        user_notification_setting.save!
+      end
+    end
+  end
+end