import Logging
import PsychrometricClient
import Routes

extension PsychrometricClient {

  private func calculateProperties(_ request: MoldRisk.Request) async throws -> PsychrometricProperties {
    try await psychrometricProperties(.dryBulb(request.temperature, relativeHumidity: request.humidity))
  }

  func respond(_ request: MoldRisk.Request, _ logger: Logger) async throws -> MoldRisk.Response {
    let properties = try await calculateProperties(request)
    let riskLevel = MoldRisk.RiskLevel(humidity: request.humidity)

    return .init(
      psychrometricProperties: properties,
      riskLevel: riskLevel,
      daysToMold: riskLevel.daysToMold,
      recommendations: .recommendations(for: request, dewPoint: properties.dewPoint, riskLevel: riskLevel)
    )
  }
}

private extension MoldRisk.RiskLevel {
  init(humidity: RelativeHumidity) {
    if humidity < 60 {
      self = .low
    } else if humidity < 70 {
      self = .moderate
    } else if humidity < 80 {
      self = .high
    } else {
      self = .severe
    }
  }

  var daysToMold: Int? {
    switch self {
    case .low: return nil
    case .moderate: return 30
    case .high: return 14
    case .severe: return 7
    }
  }
}

private extension Array where Element == String {
  static func recommendations(
    for request: MoldRisk.Request,
    dewPoint: DewPoint,
    riskLevel: MoldRisk.RiskLevel
  ) -> Self {
    var recommendations = [String]()
    if request.humidity < 60 {
      recommendations.append(
        "Reduce indoor relative humidity below 60% using dehumidification"
      )
    }
    if (request.temperature.fahrenheit - dewPoint.fahrenheit) < 4 {
      recommendations.append(
        "Increase air temperature or improve insulation to prevent condensation"
      )
    }
    if riskLevel != .low {
      recommendations.append(contentsOf: [
        "Improve ventilation to reduce moisture accumulation",
        "Inspect for and repair any water leaks or intrusion"
      ])
    }
    return recommendations
  }
}