import RxSwift

/**
Specifies how observable sequence will be repeated in case of an error
- Immediate: Will be immediatelly repeated specified number of times
- Delayed: Will be repeated after specified delay specified number of times
- ExponentialDelayed: Will be repeated specified number of times.
Delay will be incremented by multiplier after each iteration (multiplier = 0.5 means 50% increment)
- CustomTimerDelayed: Will be repeated specified number of times. Delay will be calculated by custom closure
*/
public enum RepeatBehavior {
	case immediate (maxCount: UInt)
	case delayed (maxCount: UInt, time: Double)
	case exponentialDelayed (maxCount: UInt, initial: Double, multiplier: Double)
	case customTimerDelayed (maxCount: UInt, delayCalculator: (UInt) -> DispatchTimeInterval)
}

extension RepeatBehavior {
	/**
	Extracts maxCount and calculates delay for current RepeatBehavior
	- parameter currentAttempt: Number of current attempt
	- returns: Tuple with maxCount and calculated delay for provided attempt
	*/
	func calculateConditions(_ currentRepetition: UInt) -> (maxCount: UInt, delay: DispatchTimeInterval) {
		switch self {
		case .immediate(let max):
			// if Immediate, return 0.0 as delay
			return (maxCount: max, delay: .never)
		case .delayed(let max, let time):
			// return specified delay
			return (maxCount: max, delay: .milliseconds(Int(time * 1000)))
		case .exponentialDelayed(let max, let initial, let multiplier):
			// if it's first attempt, simply use initial delay, otherwise calculate delay
			let delay = currentRepetition == 1 ? initial : initial * pow(1 + multiplier, Double(currentRepetition - 1))
			return (maxCount: max, delay: .milliseconds(Int(delay * 1000)))
		case .customTimerDelayed(let max, let delayCalculator):
			// calculate delay using provided calculator
			return (maxCount: max, delay: delayCalculator(currentRepetition))
		}
	}
}