GildedRose-Refactoring-Kata/swift/Sources/GildedRose/Items/StandardItem.swift

//
//  File.swift
//  
//
//  Created by Manali Mogre on 16/08/2020.
//

import Foundation

struct StandardItem: ItemStateUpdater {
    var item: Item
    
    private var isSellInDatePassed: Bool{
        return item.sellIn < 0
    }
    
    var decreasingValueOverZeroDaysToSell: Int {
        return 1
    }
    private var decreasingValueForZeroOrLessDaysToSell: Int {
        return 2 * decreasingValueOverZeroDaysToSell
    }
    
    private  var isItemMoreThanLowestQuality: Bool {
        return item.quality > ValueConstants.kLowestQualityValue
    }
    
    public init(item: Item) {
        self.item = item
    }
    
    func updateItemState() {
        // Reduce the sellIn days for Item by 1
        reduceSellInDays(by: 1)
        
        // Reduce the item quality by 1 , if the sell in date is passed decrement by double the value
        isSellInDatePassed ? reduceItemQuality(by: decreasingValueForZeroOrLessDaysToSell) : reduceItemQuality(by: decreasingValueOverZeroDaysToSell)
        
        guard isItemMoreThanLowestQuality else {
            // Sets the quality to zero if the quality is negative
            setItemQuality(to: ValueConstants.kLowestQualityValue)
            return
        }
    }
}