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

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
+ActiveRecord::Schema[7.1].define(version: 2024_03_20_140159) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -90,6 +90,16 @@ ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
     t.index ["target_account_id"], name: "index_account_pins_on_target_account_id"
   end
 
+  create_table "account_relationship_severance_events", force: :cascade do |t|
+    t.bigint "account_id", null: false
+    t.bigint "relationship_severance_event_id", null: false
+    t.integer "relationships_count", default: 0, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["account_id"], name: "index_account_relationship_severance_events_on_account_id", unique: true
+    t.index ["relationship_severance_event_id"], name: "idx_on_relationship_severance_event_id_403f53e707", unique: true
+  end
+
   create_table "account_stats", force: :cascade do |t|
     t.bigint "account_id", null: false
     t.bigint "statuses_count", default: 0, null: false
@@ -871,6 +881,15 @@ ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
     t.string "url"
   end
 
+  create_table "relationship_severance_events", force: :cascade do |t|
+    t.integer "type", null: false
+    t.string "target_name", null: false
+    t.boolean "purged", default: false, null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["type", "target_name"], name: "index_relationship_severance_events_on_type_and_target_name"
+  end
+
   create_table "relays", force: :cascade do |t|
     t.string "inbox_url", default: "", null: false
     t.string "follow_activity_id"
@@ -950,6 +969,21 @@ ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
     t.index ["thing_type", "thing_id", "var"], name: "index_settings_on_thing_type_and_thing_id_and_var", unique: true
   end
 
+  create_table "severed_relationships", force: :cascade do |t|
+    t.bigint "relationship_severance_event_id", null: false
+    t.bigint "local_account_id", null: false
+    t.bigint "remote_account_id", null: false
+    t.integer "direction", null: false
+    t.boolean "show_reblogs"
+    t.boolean "notify"
+    t.string "languages", array: true
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["local_account_id", "relationship_severance_event_id"], name: "index_severed_relationships_on_local_account_and_event"
+    t.index ["relationship_severance_event_id", "local_account_id", "direction", "remote_account_id"], name: "index_severed_relationships_on_unique_tuples", unique: true
+    t.index ["remote_account_id"], name: "index_severed_relationships_on_remote_account_id"
+  end
+
   create_table "site_uploads", force: :cascade do |t|
     t.string "var", default: "", null: false
     t.string "file_file_name"
@@ -1228,6 +1262,8 @@ ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
   add_foreign_key "account_notes", "accounts", on_delete: :cascade
   add_foreign_key "account_pins", "accounts", column: "target_account_id", on_delete: :cascade
   add_foreign_key "account_pins", "accounts", on_delete: :cascade
+  add_foreign_key "account_relationship_severance_events", "accounts", on_delete: :cascade
+  add_foreign_key "account_relationship_severance_events", "relationship_severance_events", on_delete: :cascade
   add_foreign_key "account_stats", "accounts", on_delete: :cascade
   add_foreign_key "account_statuses_cleanup_policies", "accounts", on_delete: :cascade
   add_foreign_key "account_warnings", "accounts", column: "target_account_id", on_delete: :cascade
@@ -1320,6 +1356,9 @@ ActiveRecord::Schema[7.1].define(version: 2024_03_10_123453) do
   add_foreign_key "scheduled_statuses", "accounts", on_delete: :cascade
   add_foreign_key "session_activations", "oauth_access_tokens", column: "access_token_id", name: "fk_957e5bda89", on_delete: :cascade
   add_foreign_key "session_activations", "users", name: "fk_e5fda67334", on_delete: :cascade
+  add_foreign_key "severed_relationships", "accounts", column: "local_account_id", on_delete: :cascade
+  add_foreign_key "severed_relationships", "accounts", column: "remote_account_id", on_delete: :cascade
+  add_foreign_key "severed_relationships", "relationship_severance_events", on_delete: :cascade
   add_foreign_key "status_edits", "accounts", on_delete: :nullify
   add_foreign_key "status_edits", "statuses", on_delete: :cascade
   add_foreign_key "status_pins", "accounts", name: "fk_d4cb435b62", on_delete: :cascade