# frozen_string_literal: true

# Packages must be unique by name - the same package is listed once per
# architecture/component in the Debian archive and the importer looks it up
# by name before inserting, so anything that lets two rows for one name appear
# (e.g. concurrent import runs) breaks the site. Production had accidentally
# relied on a constraint that was only ever added ad-hoc on some databases
# and never tracked as a migration; this makes db:migrate the single source
# of truth.
class AddUniqueNameConstraintToPackages < ActiveRecord::Migration[8.1]
  def up
    add_unique_constraint :packages, :name, name: :packages_name_key unless constraint_exists?
  end

  def down
    remove_unique_constraint :packages, :name, name: :packages_name_key if constraint_exists?
  end

  private

  def constraint_exists?
    select_value(<<~SQL.squish)
      SELECT 1
      FROM pg_constraint
      WHERE conrelid = 'packages'::regclass AND conname = 'packages_name_key' AND contype = 'u'
    SQL
  end
end