module PgHero
  module Methods
    module Basic
      def time_zone=(time_zone)
        @time_zone = time_zone.is_a?(ActiveSupport::TimeZone) ? time_zone : ActiveSupport::TimeZone[time_zone.to_s]
      end

      def time_zone
        @time_zone || Time.zone
      end

      def config
        Thread.current[:pghero_config] ||= begin
          path = "config/pghero.yml"

          config =
            (YAML.load(ERB.new(File.read(path)).result)[env] if File.exist?(path))

          if config
            config
          else
            {
              "databases" => {
                "primary" => {
                  "url" => ENV["PGHERO_DATABASE_URL"] || ActiveRecord::Base.connection_config,
                  "db_instance_identifier" => ENV["PGHERO_DB_INSTANCE_IDENTIFIER"]
                }
              }
            }
          end
        end
      end

      def settings
        names = %w(
          max_connections shared_buffers effective_cache_size work_mem
          maintenance_work_mem checkpoint_segments checkpoint_completion_target
          wal_buffers default_statistics_target
        )
        values = Hash[select_all(connection_model.send(:sanitize_sql_array, ["SELECT name, setting, unit FROM pg_settings WHERE name IN (?)", names])).sort_by { |row| names.index(row["name"]) }.map { |row| [row["name"], friendly_value(row["setting"], row["unit"])] }]
        Hash[names.map { |name| [name, values[name]] }]
      end

      def ssl_used?
        ssl_used = nil
        connection_model.transaction do
          execute("CREATE EXTENSION IF NOT EXISTS sslinfo")
          ssl_used = truthy?(select_all("SELECT ssl_is_used()").first["ssl_is_used"])
          raise ActiveRecord::Rollback
        end
        ssl_used
      end

      # Handles Rails 4 ('t') and Rails 5 (true) values.
      def truthy?(value)
        value == true || value == 't'
      end

      def falsey?(value)
        value == false || value == 'f'
      end

      private

      def friendly_value(setting, unit)
        if %w(kB 8kB).include?(unit)
          value = setting.to_i
          value *= 8 if unit == "8kB"

          if value % (1024 * 1024) == 0
            "#{value / (1024 * 1024)}GB"
          elsif value % 1024 == 0
            "#{value / 1024}MB"
          else
            "#{value}kB"
          end
        else
          "#{setting}#{unit}".strip
        end
      end

      def select_all(sql)
        # squish for logs
        connection.select_all(squish(sql)).to_a
      end

      def execute(sql)
        connection.execute(sql)
      end

      def connection_model
        databases[current_database].connection_model
      end

      def connection
        connection_model.connection
      end

      # from ActiveSupport
      def squish(str)
        str.to_s.gsub(/\A[[:space:]]+/, "").gsub(/[[:space:]]+\z/, "").gsub(/[[:space:]]+/, " ")
      end

      def quote(value)
        connection.quote(value)
      end

      def quote_table_name(value)
        connection.quote_table_name(value)
      end

      def unquote(part)
        if part && part.start_with?('"')
          part[1..-2]
        else
          part
        end
      end
    end
  end
end