Add notifications of severed relationships (#27511)

db/migrate/20240312100644_create_relationship_severance_events.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class CreateRelationshipSeveranceEvents < ActiveRecord::Migration[7.0]
+  def change
+    create_table :relationship_severance_events do |t|
+      t.integer :type, null: false
+      t.string :target_name, null: false
+      t.boolean :purged, null: false, default: false
+
+      t.timestamps
+
+      t.index [:type, :target_name]
+    end
+  end
+end

db/migrate/20240312105620_create_severed_relationships.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+class CreateSeveredRelationships < ActiveRecord::Migration[7.0]
+  def change
+    create_table :severed_relationships do |t|
+      # No need to have an index on this foreign key as it is covered by `index_severed_relationships_on_unique_tuples`
+      t.references :relationship_severance_event, null: false, foreign_key: { on_delete: :cascade }, index: false
+
+      # No need to have an index on this foregin key as it is covered by `index_severed_relationships_on_local_account_and_event`
+      t.references :local_account, null: false, foreign_key: { to_table: :accounts, on_delete: :cascade }, index: false
+      t.references :remote_account, null: false, foreign_key: { to_table: :accounts, on_delete: :cascade }
+
+      # Used to describe whether `local_account` is the active (follower) or passive (followed) part of the relationship
+      t.integer :direction, null: false
+
+      # Those attributes are carried over from the `follows` table
+      t.boolean :show_reblogs
+      t.boolean :notify
+      t.string :languages, array: true
+
+      t.timestamps
+
+      t.index [:relationship_severance_event_id, :local_account_id, :direction, :remote_account_id], name: 'index_severed_relationships_on_unique_tuples', unique: true
+      t.index [:local_account_id, :relationship_severance_event_id], name: 'index_severed_relationships_on_local_account_and_event'
+    end
+  end
+end

db/migrate/20240320140159_create_account_relationship_severance_events.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class CreateAccountRelationshipSeveranceEvents < ActiveRecord::Migration[7.1]
+  def change
+    create_table :account_relationship_severance_events do |t|
+      t.belongs_to :account, foreign_key: { on_delete: :cascade }, null: false, index: { unique: true }
+      t.belongs_to :relationship_severance_event, foreign_key: { on_delete: :cascade }, null: false, index: { unique: true }
+
+      t.integer :relationships_count, default: 0, null: false
+
+      t.timestamps
+    end
+  end
+end