Add option to be notified when a followed user posts (#13546)

* Add bell button

Fix #4890

* Remove duplicate type from post-deployment migration

* Fix legacy class type mappings

* Improve query performance with better index

* Fix validation

* Remove redundant index from notifications

6 files changed, 73 insertions, 3 deletions

diff --git a/db/migrate/20200917192924_add_notify_to_follows.rb b/db/migrate/20200917192924_add_notify_to_follows.rb
new file mode 100644
index 000000000..d27471c44
--- /dev/null
+++ b/db/migrate/20200917192924_add_notify_to_follows.rb
@@ -0,0 +1,19 @@
+require Rails.root.join('lib', 'mastodon', 'migration_helpers')
+
+class AddNotifyToFollows < ActiveRecord::Migration[5.1]
+  include Mastodon::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def up
+    safety_assured do
+      add_column_with_default :follows, :notify, :boolean, default: false, allow_null: false
+      add_column_with_default :follow_requests, :notify, :boolean, default: false, allow_null: false
+    end
+  end
+
+  def down
+    remove_column :follows, :notify
+    remove_column :follow_requests, :notify
+  end
+end
diff --git a/db/migrate/20200917193034_add_type_to_notifications.rb b/db/migrate/20200917193034_add_type_to_notifications.rb
new file mode 100644
index 000000000..002be3aa0
--- /dev/null
+++ b/db/migrate/20200917193034_add_type_to_notifications.rb
@@ -0,0 +1,5 @@
+class AddTypeToNotifications < ActiveRecord::Migration[5.2]
+  def change
+    add_column :notifications, :type, :string
+  end
+end
diff --git a/db/migrate/20200917222316_add_index_notifications_on_type.rb b/db/migrate/20200917222316_add_index_notifications_on_type.rb
new file mode 100644
index 000000000..9bd23c1d3
--- /dev/null
+++ b/db/migrate/20200917222316_add_index_notifications_on_type.rb
@@ -0,0 +1,7 @@
+class AddIndexNotificationsOnType < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def change
+    add_index :notifications, [:account_id, :id, :type], order: { id: :desc }, algorithm: :concurrently
+  end
+end
diff --git a/db/post_migrate/20200917193528_migrate_notifications_type.rb b/db/post_migrate/20200917193528_migrate_notifications_type.rb
new file mode 100644
index 000000000..88e423084
--- /dev/null
+++ b/db/post_migrate/20200917193528_migrate_notifications_type.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class MigrateNotificationsType < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  TYPES_TO_MIGRATE = {
+    'Mention'       => :mention,
+    'Status'        => :reblog,
+    'Follow'        => :follow,
+    'FollowRequest' => :follow_request,
+    'Favourite'     => :favourite,
+    'Poll'          => :poll,
+  }.freeze
+
+  def up
+    TYPES_TO_MIGRATE.each_pair do |activity_type, type|
+      Notification.where(activity_type: activity_type, type: nil).in_batches.update_all(type: type)
+    end
+  end
+
+  def down; end
+end
diff --git a/db/post_migrate/20200917222734_remove_index_notifications_on_account_activity.rb b/db/post_migrate/20200917222734_remove_index_notifications_on_account_activity.rb
new file mode 100644
index 000000000..cb7f78e53
--- /dev/null
+++ b/db/post_migrate/20200917222734_remove_index_notifications_on_account_activity.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class RemoveIndexNotificationsOnAccountActivity < ActiveRecord::Migration[5.2]
+  disable_ddl_transaction!
+
+  def up
+    remove_index :notifications, name: :account_activity
+    remove_index :notifications, name: :index_notifications_on_account_id_and_id
+  end
+
+  def down
+    add_index :notifications, [:account_id, :activity_id, :activity_type], unique: true, name: 'account_activity', algorithm: :concurrently
+    add_index :notifications, [:account_id, :id], order: { id: :desc }, algorithm: :concurrently
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 038e39130..0029d620a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_09_08_193330) do
+ActiveRecord::Schema.define(version: 2020_09_17_222734) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -411,6 +411,7 @@ ActiveRecord::Schema.define(version: 2020_09_08_193330) do
     t.bigint "target_account_id", null: false
     t.boolean "show_reblogs", default: true, null: false
     t.string "uri"
+    t.boolean "notify", default: false, null: false
     t.index ["account_id", "target_account_id"], name: "index_follow_requests_on_account_id_and_target_account_id", unique: true
   end
 
@@ -421,6 +422,7 @@ ActiveRecord::Schema.define(version: 2020_09_08_193330) do
     t.bigint "target_account_id", null: false
     t.boolean "show_reblogs", default: true, null: false
     t.string "uri"
+    t.boolean "notify", default: false, null: false
     t.index ["account_id", "target_account_id"], name: "index_follows_on_account_id_and_target_account_id", unique: true
     t.index ["target_account_id"], name: "index_follows_on_target_account_id"
   end
@@ -545,8 +547,8 @@ ActiveRecord::Schema.define(version: 2020_09_08_193330) do
     t.datetime "updated_at", null: false
     t.bigint "account_id", null: false
     t.bigint "from_account_id", null: false
-    t.index ["account_id", "activity_id", "activity_type"], name: "account_activity", unique: true
-    t.index ["account_id", "id"], name: "index_notifications_on_account_id_and_id", order: { id: :desc }
+    t.string "type"
+    t.index ["account_id", "id", "type"], name: "index_notifications_on_account_id_and_id_and_type", order: { id: :desc }
     t.index ["activity_id", "activity_type"], name: "index_notifications_on_activity_id_and_activity_type"
     t.index ["from_account_id"], name: "index_notifications_on_from_account_id"
   end