Default follows for new users (#4871)

When a new user confirms their e-mail, bootstrap their home timeline
by automatically following a set of accounts. By default, all local
admin accounts (that are unlocked). Can be customized by new admin
setting (comma-separated usernames, local and unlocked only)

app/controllers/admin/settings_controller.rb

@@ -13,6 +13,7 @@ module Admin
       closed_registrations_message
       open_deletion
       timeline_preview
+      bootstrap_timeline_accounts
     ).freeze
 
     BOOLEAN_SETTINGS = %w(

app/controllers/auth/confirmations_controller.rb

@@ -2,4 +2,10 @@
 
 class Auth::ConfirmationsController < Devise::ConfirmationsController
   layout 'auth'
+
+  def show
+    super do |user|
+      BootstrapTimelineWorker.perform_async(user.account_id) if user.errors.empty?
+    end
+  end
 end

app/models/form/admin_settings.rb

@@ -24,6 +24,8 @@ class Form::AdminSettings
     :open_deletion=,
     :timeline_preview,
     :timeline_preview=,
+    :bootstrap_timeline_accounts,
+    :bootstrap_timeline_accounts=,
     to: Setting
   )
 end

app/services/bootstrap_timeline_service.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+class BootstrapTimelineService < BaseService
+  def call(source_account)
+    bootstrap_timeline_accounts.each do |target_account|
+      FollowService.new.call(source_account, target_account)
+    end
+  end
+
+  private
+
+  def bootstrap_timeline_accounts
+    return @bootstrap_timeline_accounts if defined?(@bootstrap_timeline_accounts)
+
+    @bootstrap_timeline_accounts = bootstrap_timeline_accounts_usernames.empty? ? admin_accounts : local_unlocked_accounts(bootstrap_timeline_accounts_usernames)
+  end
+
+  def bootstrap_timeline_accounts_usernames
+    @bootstrap_timeline_accounts_usernames ||= (Setting.bootstrap_timeline_accounts || '').split(',').map { |str| str.strip.gsub(/\A@/, '') }.reject(&:blank?)
+  end
+
+  def admin_accounts
+    User.admins
+        .includes(:account)
+        .where(accounts: { locked: false })
+        .map(&:account)
+  end
+
+  def local_unlocked_accounts(usernames)
+    Account.local
+           .where(username: usernames)
+           .where(locked: false)
+  end
+end

app/services/follow_service.rb

@@ -5,9 +5,9 @@ class FollowService < BaseService
 
   # Follow a remote user, notify remote user about the follow
   # @param [Account] source_account From which to follow
-  # @param [String] uri User URI to follow in the form of username@domain
+  # @param [String, Account] uri User URI to follow in the form of username@domain (or account record)
   def call(source_account, uri)
-    target_account = ResolveRemoteAccountService.new.call(uri)
+    target_account = uri.is_a?(Account) ? uri : ResolveRemoteAccountService.new.call(uri)
 
     raise ActiveRecord::RecordNotFound if target_account.nil? || target_account.id == source_account.id || target_account.suspended?
     raise Mastodon::NotPermittedError  if target_account.blocking?(source_account) || source_account.blocking?(target_account)

app/views/admin/settings/edit.html.haml

@@ -28,5 +28,10 @@
     = f.input :site_extended_description, wrapper: :with_block_label, as: :text, label: t('admin.settings.site_description_extended.title'), hint: t('admin.settings.site_description_extended.desc_html'), input_html: { rows: 8 }
     = f.input :site_terms, wrapper: :with_block_label, as: :text, label: t('admin.settings.site_terms.title'), hint: t('admin.settings.site_terms.desc_html'), input_html: { rows: 8 }
 
+  %hr/
+
+  .fields-group
+    = f.input :bootstrap_timeline_accounts, wrapper: :with_block_label, label: t('admin.settings.bootstrap_timeline_accounts.title'), hint: t('admin.settings.bootstrap_timeline_accounts.desc_html')
+
   .actions
     = f.button :button, t('generic.save_changes'), type: :submit

app/workers/bootstrap_timeline_worker.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class BootstrapTimelineWorker
+  include Sidekiq::Worker
+
+  def perform(account_id)
+    BootstrapTimelineService.new.call(Account.find(account_id))
+  end
+end