public struct PalletHelper {

    static func findClosestFactor(conversionFactors: [ConversionFactor], baseUnit: String) -> ConversionFactorUnit? {
        let conversionUnitParser = CFUnitParser(conversionFactors)
        return conversionUnitParser.convertFromPalle(to: baseUnit)
    }

    static func findDenominatorByAmount(amount: Int, numerator: Double) -> Double {
        let value: Double = Double(amount) / numerator
        let denominator = value >= 1 ? value : 1
        let remainder = denominator.remainder(dividingBy: 1)
        return Double(denominator - remainder + ((remainder <= 0.30 || remainder >= 0.70) ? round(remainder) : 0.0))
    }

    static func isWithinRange(amount: Int, convertedAmount: Double, conversionFactor: Double) -> Bool {
        let baseValue: Double = Double(convertedAmount)
        let numeratorFraction: Double = conversionFactor * 0.25
        let lower = Int(floor(baseValue - numeratorFraction))
        let upper = Int(ceil(baseValue + numeratorFraction))
        return (lower..<upper).contains(amount)
    }
    static func isValidAmount(amount: Int, conversionFactorUnit: ConversionFactorUnit?) -> Bool {
        guard let weight = conversionFactorUnit?.weight, amount != 1 else {return false}
        let numerator = Double(weight)
        let multipliedValue : Double = round((Double(amount) / numerator)) * numerator
        if multipliedValue != floor(multipliedValue) || multipliedValue == 0 {
            return false
        }
        return isWithinRange(amount: amount, convertedAmount : multipliedValue, conversionFactor: numerator) && amount != Int(multipliedValue)
    }

    // If a pallet popup silence date has been set, then check if the 30 days have past
    static func isPalletPopupIsSilenced() -> Bool {
        guard let past = UserDefaultsHelper().getPalletPopupSilenceDate(), let diff = Calendar.current.dateComponents([.day], from: past, to: Date()).day else {
            return false
        }

        return (diff < 30)
    }
}

public enum PalletState {
    case change(quantity: Int)
    case insufficient
    case close
}

public extension UIViewController {
    func showPalletPopup(_ conversionFactor: ConversionFactorUnit?, _ amount: Int, _ completion: @escaping ((PalletState) -> ())) {
        guard let vc = PalletPopupConfig.regular(amount: amount, conversionFactor: conversionFactor, completion: completion) as? UIViewController & SheetControllerPresentable else { return }
        if UIDevice.dlg_isPad() {
            vc.modalPresentationStyle = .custom
            present(vc, animated: true, completion: nil)
        } else {
            let sheetVC = SheetViewController(controller: vc, configuration: .init(canBeDismissed: false, showControllerTitle: false, dismissableButton: false, hiddenBar: true))
            present(sheetVC, animated: true, completion: nil)
        }
    }

    func handlePallet(amount: Int, conversionFactors: [ConversionFactor], baseUnit: String, completion: @escaping ((PalletState) -> ())) {
        if PalletHelper.isPalletPopupIsSilenced() {
            completion(.close)
            return
        }

        let closestFactor = PalletHelper.findClosestFactor(conversionFactors: conversionFactors, baseUnit: baseUnit)
        let valid = PalletHelper.isValidAmount(amount: amount, conversionFactorUnit: closestFactor)

        if valid {
            showPalletPopup(closestFactor, amount, completion)
        } else {
            completion(.insufficient)
        }
    }
}