module FastSeeder
  module Adapters
    class BaseAdapter
      def initialize(conn, record_set)
	@conn       = conn
	@record_set = record_set
      end

      def insert!
	sql = build_sql
	@conn.execute(sql)
      end


      private

      def build_sql
	columns_str = build_columns_str
	values_str  = build_values_str
	"INSERT INTO #{@record_set.table} (#{columns_str}) VALUES #{values_str}"
      end

      def build_columns_str
	column_names = @record_set.columns
	column_names << 'created_at' if process_created_at?
	column_names << 'updated_at' if process_updated_at?
	column_names.join(", ")
      end

      def build_values_str
	values = @record_set.values.map do |vals|
	  build_record_values_str(vals)
	end
	values.join(", ")
      end

      def build_record_values_str(values)
	vals = values.dup
	vals << Time.zone.now if process_created_at?
	vals << Time.zone.now if process_updated_at?
	quoted_vals = vals.map { |val| @conn.quote(val) }
	joint_vals =  quoted_vals.join(", ")
	"(#{joint_vals})"
      end


      def process_created_at?
	@process_created_at ||= process_timestamp?('created_at')
      end

      def process_updated_at?
	@process_updated_at ||= process_timestamp?('updated_at')
      end

      def process_timestamp?(column_name)
	@record_set.model_class.column_names.include?(column_name.to_s) &&
	  !@record_set.columns.include?(column_name.to_s)
      end

    end
  end
end