import Models

extension Derating.Request {
  func respond() async throws -> Derating.Response {
    switch systemType {
    case .airToAir:
      return .init(
        coolingTotal: totalWetDerating(elevation: elevation),
        coolingSensible: sensibleWetDerating(elevation: elevation),
        heating: totalDryDerating(elevation: elevation)
      )

    case let .heatingOnly(type: type):
      switch type {
      case .boiler, .furnace:
        return .init(heating: furnaceDerating(elevation: elevation))
      case .electric:
        return .init(heating: 1)
      }
    }
  }
}

// swiftlint:disable cyclomatic_complexity
private func furnaceDerating(elevation: Int) -> Double {
  guard elevation > 0 else { return 1 }

  if (0 ..< 1000).contains(elevation) { return 1 }
  if (1000 ..< 2000).contains(elevation) { return 0.96 }
  if (2000 ..< 3000).contains(elevation) { return 0.92 }
  if (3000 ..< 4000).contains(elevation) { return 0.88 }
  if (4000 ..< 5000).contains(elevation) { return 0.84 }
  if (5000 ..< 6000).contains(elevation) { return 0.8 }
  if (6000 ..< 7000).contains(elevation) { return 0.76 }
  if (7000 ..< 8000).contains(elevation) { return 0.72 }
  if (8000 ..< 9000).contains(elevation) { return 0.68 }
  if (9000 ..< 10000).contains(elevation) { return 0.64 }
  if (10000 ..< 11000).contains(elevation) { return 0.6 }
  if (11000 ..< 12000).contains(elevation) { return 0.56 }
  // greater than 12,000 feet in elevation.
  return 0.52
}

private func totalWetDerating(elevation: Int) -> Double {
  guard elevation > 0 else { return 1 }

  if (0 ..< 1000).contains(elevation) { return 1 }
  if (1000 ..< 2000).contains(elevation) { return 0.99 }
  if (2000 ..< 3000).contains(elevation) { return 0.98 }
  if (3000 ..< 4000).contains(elevation) { return 0.98 }
  if (4000 ..< 5000).contains(elevation) { return 0.97 }
  if (5000 ..< 6000).contains(elevation) { return 0.96 }
  if (6000 ..< 7000).contains(elevation) { return 0.95 }
  if (7000 ..< 8000).contains(elevation) { return 0.94 }
  if (8000 ..< 9000).contains(elevation) { return 0.94 }
  if (9000 ..< 10000).contains(elevation) { return 0.93 }
  if (10000 ..< 11000).contains(elevation) { return 0.92 }
  if (11000 ..< 12000).contains(elevation) { return 0.91 }
  // greater than 12,000 feet in elevation.
  return 0.9
}

private func sensibleWetDerating(elevation: Int) -> Double {
  guard elevation > 0 else { return 1 }

  if (0 ..< 1000).contains(elevation) { return 1 }
  if (1000 ..< 2000).contains(elevation) { return 0.97 }
  if (2000 ..< 3000).contains(elevation) { return 0.94 }
  if (3000 ..< 4000).contains(elevation) { return 0.91 }
  if (4000 ..< 5000).contains(elevation) { return 0.88 }
  if (5000 ..< 6000).contains(elevation) { return 0.85 }
  if (6000 ..< 7000).contains(elevation) { return 0.82 }
  if (7000 ..< 8000).contains(elevation) { return 0.8 }
  if (8000 ..< 9000).contains(elevation) { return 0.77 }
  if (9000 ..< 10000).contains(elevation) { return 0.74 }
  if (10000 ..< 11000).contains(elevation) { return 0.71 }
  if (11000 ..< 12000).contains(elevation) { return 0.68 }
  // greater than 12,000 feet in elevation.
  return 0.65
}

private func totalDryDerating(elevation: Int) -> Double {
  guard elevation > 0 else { return 1 }

  if (0 ..< 1000).contains(elevation) { return 1 }
  if (1000 ..< 2000).contains(elevation) { return 0.98 }
  if (2000 ..< 3000).contains(elevation) { return 0.97 }
  if (3000 ..< 4000).contains(elevation) { return 0.95 }
  if (4000 ..< 5000).contains(elevation) { return 0.94 }
  if (5000 ..< 6000).contains(elevation) { return 0.92 }
  if (6000 ..< 7000).contains(elevation) { return 0.9 }
  if (7000 ..< 8000).contains(elevation) { return 0.89 }
  if (8000 ..< 9000).contains(elevation) { return 0.87 }
  if (9000 ..< 10000).contains(elevation) { return 0.86 }
  if (10000 ..< 11000).contains(elevation) { return 0.84 }
  if (11000 ..< 12000).contains(elevation) { return 0.82 }
  // greater than 12,000 feet in elevation.
  return 0.81
}

// swiftlint:enable cyclomatic_complexity