import Dependencies
import Logging
import PsychrometricClient
import Routes

public extension HydronicSystemPressure.Request {

  func respond(logger: Logger) async throws -> HydronicSystemPressure.Response {
    @Dependency(\.psychrometricClient) var psychrometricClient

    try validate()

    let waterTemperature = DryBulb.fahrenheit(self.waterTemperature ?? 60)

    let density = try await psychrometricClient.density.water(waterTemperature)
    let pressure = height * (density.value / 144) + 5
    var warnings = [String]()

    if self.waterTemperature == nil {
      warnings.append(
        """
        Calculations based on default water temperature of 60°F.
        """
      )
    }

    return .init(pressure: pressure, waterDensity: density, warnings: warnings)
  }

  private func validate() throws {
    guard height > 0 else {
      throw ValidationError(message: "Height should be greater than 0.")
    }
    if let waterTemperature {
      guard waterTemperature > 32 else {
        throw ValidationError(message: "Water temperature should be above freezing.")
      }
    }
  }
}