require 'database_cleaner/sequel/truncation'

module DatabaseCleaner
  module Sequel
    class Deletion < Truncation
      def disable_referential_integrity(tables)
        case db.database_type
        when :postgres
          db.run('SET CONSTRAINTS ALL DEFERRED')
          tables_to_truncate(db).each do |table|
            db.run("ALTER TABLE \"#{table}\" DISABLE TRIGGER ALL")
          end
        when :mysql
          old = db.fetch('SELECT @@FOREIGN_KEY_CHECKS').first[:@@FOREIGN_KEY_CHECKS]
          db.run('SET FOREIGN_KEY_CHECKS = 0')
        end
        yield
      ensure
        case db.database_type
        when :postgres
          tables.each do |table|
            db.run("ALTER TABLE \"#{table}\" ENABLE TRIGGER ALL")
          end
        when :mysql
          db.run("SET FOREIGN_KEY_CHECKS = #{old}")
        end
      end

      def delete_tables(db, tables)
        tables.each do |table|
          db[table.to_sym].delete
        end
      end

      def clean
        return unless dirty?

        tables = tables_to_truncate(db)
        db.transaction do
          disable_referential_integrity(tables) do
            delete_tables(db, tables)
          end
        end
      end
    end
  end
end