brightdigit/OrchardNest

import Foundation

enum Component {
  case second
  case minute
  case hour
  case day
  case week
  case month
  case year

  func timeInterval() -> TimeInterval {
    switch self {
    case .second:
      return .second
    case .minute:
      return .minute
    case .hour:
      return .hour
    case .day:
      return .day
    case .week:
      return .week
    case .month:
      return .month
    case .year:
      return .year
    }
  }

  func stepDown() -> (duration: Int, component: Component) {
    switch self {
    case .year:
      return (duration: 12, component: .month)
    case .month:
      return (duration: 30, component: .day)
    case .week:
      return (duration: 7, component: .day)
    case .day:
      return (duration: 24, component: .hour)
    case .hour:
      return (duration: 60, component: .minute)
    case .minute:
      return (duration: 60, component: .second)
    case .second:
      return (duration: 1, component: .second)
    }
  }

  func toCalendarComponent() -> Calendar.Component {
    switch self {
    case .year:
      return .year
    case .month:
      return .month
    case .week:
      return .day
    case .day:
      return .day
    case .hour:
      return .hour
    case .minute:
      return .minute
    case .second:
      return .second
    }
  }

  func value(duration: Double) -> [ComponentDuration] {
    var correctedDuration = duration
    if self == .week {
      correctedDuration *= 7
    }
    let intValue = Int(correctedDuration.rounded(.down))
    var output: [ComponentDuration] = []

    output.append(ComponentDuration(duration: intValue, component: toCalendarComponent()))
    let remainedDuration = duration - Double(intValue)
    if remainedDuration > 0.0001 {
      let step = stepDown()
      let recalculatedRemainedDuration = Double(step.duration) * remainedDuration
      let intRecalculatedRemainedDuration = Int(recalculatedRemainedDuration.rounded(.down))
      output.append(ComponentDuration(duration: intRecalculatedRemainedDuration, component: step.component.toCalendarComponent()))
    }
    return output
  }
}