import Foundation

public enum EquipmentMeasurement: Equatable {
 
  case airHandler(AirHandler)
  case furnaceAndCoil(FurnaceAndCoil)
  
  public var equipmentType: EquipmentType {
    switch self {
    case .airHandler:
      return .airHandler
    case .furnaceAndCoil:
      return .furnaceAndCoil
    }
  }
  
  public var externalStaticPressure: Double {
    switch self {
    case let .airHandler(airHandler):
      return airHandler.externalStaticPressure
    case let .furnaceAndCoil(furnaceAndCoil):
      return furnaceAndCoil.externalStaticPressure
    }
  }
  
  public struct AirHandler: Equatable {

    @Positive
    public var airflow: Double?

    @Positive
    public var returnPlenumPressure: Double?
    
    @Positive
    public var postFilterPressure: Double?
    
    @Positive
    public var postCoilPressure: Double?
    
    @Positive
    public var supplyPlenumPressure: Double?
    
    public init(
      airflow: Double? = nil,
      returnPlenumPressure: Double? = nil,
      postFilterPressure: Double? = nil,
      postCoilPressure: Double? = nil,
      supplyPlenumPressure: Double? = nil
    ) {
      self.airflow = airflow
      self.returnPlenumPressure = returnPlenumPressure
      self.postFilterPressure = postFilterPressure
      self.postCoilPressure = postCoilPressure
      self.supplyPlenumPressure = supplyPlenumPressure
    }
    
    public var externalStaticPressure: Double {
      ($returnPlenumPressure.positiveValue ?? 0) + ($supplyPlenumPressure.positiveValue ?? 0)
    }
  }
  
  public struct FurnaceAndCoil: Equatable {

    @Positive
    public var airflow: Double?

    @Positive
    public var returnPlenumPressure: Double?
    
    @Positive
    public var postFilterPressure: Double?
    
    @Positive
    public var preCoilPressure: Double?
    
    @Positive
    public var supplyPlenumPressure: Double?
    
    public init(
      airflow: Double? = nil,
      returnPlenumPressure: Double? = nil,
      postFilterPressure: Double? = nil,
      preCoilPressure: Double? = nil,
      supplyPlenumPressure: Double? = nil
    ) {
      self.airflow = airflow
      self.returnPlenumPressure = returnPlenumPressure
      self.postFilterPressure = postFilterPressure
      self.preCoilPressure = preCoilPressure
      self.supplyPlenumPressure = supplyPlenumPressure
    }
    
    public var externalStaticPressure: Double {
      ($postFilterPressure.positiveValue ?? 0) + ($preCoilPressure.positiveValue ?? 0)
    }
  }
}

extension EquipmentMeasurement.AirHandler {
  
  public enum Key: String, Equatable, CaseIterable {
    case returnPlenumPressure
    case postFilterPressure
    case postCoilPressure
    case supplyPlenumPressure
    case airflow
  }
}

extension EquipmentMeasurement.FurnaceAndCoil {
  
  public enum Key: String, Equatable, CaseIterable {
    case returnPlenumPressure
    case postFilterPressure
    case preCoilPressure
    case supplyPlenumPressure
    case airflow
  }
}