UnitExtensions.swift

//
//  UnitExtensions.swift
//  RunForFun
//
//  Created by Константин Малков on 23.08.2020.
//  Copyright © 2020 Malkov Kostia. All rights reserved.
//

//класс с конвертацией полученных данных в нужный формат
//
import Foundation

class UnitConverterPace: UnitConverter {
  private let coefficient: Double
  
  init(coefficient: Double) {
    self.coefficient = coefficient
  }
  
  override func baseUnitValue(fromValue value: Double) -> Double {
    return reciprocal(value * coefficient)
  }
  
  override func value(fromBaseUnitValue baseUnitValue: Double) -> Double {
    return reciprocal(baseUnitValue * coefficient)
  }
  
  private func reciprocal(_ value: Double) -> Double {
    guard value != 0 else { return 0 }
    return 1.0 / value
  }
}

extension UnitSpeed {
  class var secondsPerMeter: UnitSpeed {
    return UnitSpeed(symbol: "сек/м", converter: UnitConverterPace(coefficient: 1))
  }
  
  class var minutesPerKilometer: UnitSpeed {
    return UnitSpeed(symbol: "мин/км", converter: UnitConverterPace(coefficient: 60.0 / 1000.0))
  }
  
  class var minutesPerMile: UnitSpeed {
    return UnitSpeed(symbol: "мин/мил", converter: UnitConverterPace(coefficient: 60.0 / 1609.34))
  }
}