module ActsAsArchive
  module Base
    module Table

      def self.included(base)
        unless base.included_modules.include?(InstanceMethods)
          base.send :extend, ClassMethods
          base.send :include, InstanceMethods

          if base.connection.class.to_s.include?('Mysql')
            base.send :extend, ActsAsArchive::Base::Adapters::MySQL
          elsif base.connection.class.to_s.include?('PostgreSQL')
            base.send :extend, ActsAsArchive::Base::Adapters::PostgreSQL
          else
            raise 'acts_as_archive does not support this database adapter'
          end
        end
      end

      module ClassMethods

        def archive_table_exists?
          connection.table_exists?("archived_#{table_name}")
        end

        def create_archive_table
          if table_exists? && !archive_table_exists?
            connection.execute(%{
              CREATE TABLE archived_#{table_name}
                #{"ENGINE=InnoDB" if connection.class.to_s.include?('Mysql')}
                AS SELECT * from #{table_name}
                WHERE false;
            })
            columns = connection.columns("archived_#{table_name}").collect(&:name)
            unless columns.include?('deleted_at')
              connection.add_column("archived_#{table_name}", :deleted_at, :datetime)
            end
          end
        end

        def create_archive_indexes
          if archive_table_exists?
            indexes = archive_table_indexed_columns

            (archive_indexes - indexes).each do |index|
              connection.add_index("archived_#{table_name}", index, :name => index_name_for(table_name, index))  if table_has_columns(index)
            end
            (indexes - archive_indexes).each do |index|
              connection.remove_index("archived_#{table_name}", index) if table_has_columns(index)
            end
          end
        end


        def migrate_from_acts_as_paranoid
          if column_names.include?('deleted_at')
            if table_exists? && archive_table_exists?
              condition = "deleted_at IS NOT NULL"
              if self.count_by_sql("SELECT COUNT(*) FROM #{table_name} WHERE #{condition}") > 0
                # Base::Destroy.copy_to_archive
                copy_to_archive(condition, true)
              end
            end
          end
        end

        private

        # def archive_table_indexed_columns
        #   case connection.class.to_s
        #   when "ActiveRecord::ConnectionAdapters::MysqlAdapter"
        #     index_query = "SHOW INDEX FROM archived_#{table_name}"
        #     indexes = connection.select_all(index_query).collect do |r|
        #       r["Column_name"]
        #     end
        #   when "ActiveRecord::ConnectionAdapters::PostgreSQLAdapter"
        #     index_query = "SELECT indexname FROM pg_indexes WHERE tablename = '#{table_name}'"
        #     indexes = connection.select_all(index_query).collect do |r|
        #       r["indexname"].split("_on_").last.split("_and_")
        #     end
        #   else
        #     raise "Unsupported Database"
        #   end
        # end

        def table_has_columns(columns)
          !Array(columns).select {|current_column| self::Archive.column_names.include?(current_column.to_s)}.empty?
        end

        def index_name_for(table_name, index)
          "index_by_#{Array(index).join("_and_")}".to_sym if "index_archived_#{table_name}_on_#{Array(index).join("_and_")}".length > 63
        end
      end

      module InstanceMethods
      end
    end
  end
end