class Standard
  # Add transformers for some prototypes
  #
  # @param model [OpenStudio::Model::Model] OpenStudio model object
  # @param wired_lighting_frac [Double] the wired lighting fraction, 0-1
  # @param transformer_size [Double] the transformer size in VA
  # @param transformer_efficiency [Double] the transformer efficiency, 0-1
  # @param excluded_interiorequip_key [String] key to exclude
  # @param excluded_interiorequip_meter [String] meter to exclude
  # @return [OpenStudio::Model::ElectricLoadCenterTransformer] the transformer object
  def model_add_transformer(model,
                            wired_lighting_frac: nil,
                            transformer_size: nil,
                            transformer_efficiency: nil,
                            excluded_interiorequip_key: '',
                            excluded_interiorequip_meter: nil)
    # throw an error if transformer properties are missing
    if wired_lighting_frac.nil? || transformer_size.nil? || transformer_efficiency.nil?
      OpenStudio.logFree(OpenStudio::Error, 'openstudio.Model.transformers', "Either 'wired_lighting_frac', 'transformer_size', or 'transformer_efficiency' is unspecified.  Cannot add transformer.")
      return false
    end

    # @todo default values are for testing only
    # ems sensor for interior lighting
    facility_int_ltg = OpenStudio::Model::EnergyManagementSystemSensor.new(model, 'InteriorLights:Electricity')
    facility_int_ltg.setName('Facility_Int_LTG')

    # declaire ems variable for transformer wired lighting portion
    wired_ltg_var = OpenStudio::Model::EnergyManagementSystemGlobalVariable.new(model, 'Wired_LTG')

    # ems program for transformer load
    transformer_load_prog = OpenStudio::Model::EnergyManagementSystemProgram.new(model)
    transformer_load_prog.setName('Transformer_Load_Prog')
    transformer_load_prog_body = <<-EMS
    SET Wired_LTG = Facility_Int_LTG*#{wired_lighting_frac}
    EMS
    transformer_load_prog.setBody(transformer_load_prog_body)

    # ems program calling manager
    transformer_load_prog_manager = OpenStudio::Model::EnergyManagementSystemProgramCallingManager.new(model)
    transformer_load_prog_manager.setName('Transformer_Load_Prog_Manager')
    transformer_load_prog_manager.setCallingPoint('AfterPredictorAfterHVACManagers')
    transformer_load_prog_manager.addProgram(transformer_load_prog)

    # ems output variable
    wired_ltg_emsout = OpenStudio::Model::EnergyManagementSystemOutputVariable.new(model, wired_ltg_var)
    wired_ltg_emsout.setName('Wired_LTG')
    wired_ltg_emsout.setTypeOfDataInVariable('Summed')
    wired_ltg_emsout.setUpdateFrequency('ZoneTimeStep')
    wired_ltg_emsout.setUnits('J')

    # meter for ems output
    wired_ltg_meter = OpenStudio::Model::MeterCustom.new(model)
    wired_ltg_meter.setName('Wired_LTG_Electricity')
    wired_ltg_meter.setFuelType('Electricity')
    wired_ltg_meter.addKeyVarGroup('', 'Wired_LTG')

    # meter for wired int equip
    unless excluded_interiorequip_meter.nil?
      wired_int_equip_meter = OpenStudio::Model::MeterCustomDecrement.new(model, 'InteriorEquipment:Electricity')
      wired_int_equip_meter.setName('Wired_Int_EQUIP')
      wired_int_equip_meter.setFuelType('Electricity')
      wired_int_equip_meter.addKeyVarGroup(excluded_interiorequip_key, excluded_interiorequip_meter)
    end

    # add transformer
    transformer = OpenStudio::Model::ElectricLoadCenterTransformer.new(model)
    transformer.setName('Transformer_1')
    transformer.setAvailabilitySchedule(model.alwaysOnDiscreteSchedule)
    transformer.setTransformerUsage('PowerInFromGrid')
    transformer.setRatedCapacity(transformer_size)
    transformer.setPhase('3')
    transformer.setConductorMaterial('Aluminum')
    transformer.setFullLoadTemperatureRise(150)
    transformer.setFractionofEddyCurrentLosses(0.1)
    transformer.setPerformanceInputMethod('NominalEfficiency')
    transformer.setNameplateEfficiency(transformer_efficiency)
    transformer.setPerUnitLoadforNameplateEfficiency(0.35)
    transformer.setReferenceTemperatureforNameplateEfficiency(75)
    transformer.setConsiderTransformerLossforUtilityCost(true)
    transformer.addMeter('Wired_LTG_Electricity')
    if excluded_interiorequip_meter.nil?
      transformer.addMeter('InteriorEquipment:Electricity') # by default, add this as the second meter
    else
      transformer.addMeter('Wired_Int_EQUIP')
    end

    return transformer
  end
end