concentrationModel.swift

//
//  concentrationModel.swift
//  Concentration
//
//  Created by BHAVANASINGH on 04/01/19.
//  Copyright © 2019 Stanford University. All rights reserved.
//

import Foundation
class Concentration
{
    private var score = 0
    var cards = [Card]()
    private var oneAndOnlyOneCardFaceUp : Int?{
        get{
            return cards.indices.filter{ cards[$0].isFaceUp }.oneAndOnly
        }
        set{
            for index in cards.indices{
                cards[index].isFaceUp = (newValue == index)
            }
        }
    }
    
    init(numberOfPairOfCards: Int){
        assert(numberOfPairOfCards > 0, "Concentration.numberOfPairOfCards: = Should be atleast 1")
        for _ in 1...numberOfPairOfCards{
            let card = Card()
            cards += [card, card]
        }
        cards.shuffle()
        
    }
    
    func chooseCard(at index: Int){
        assert(cards.indices.contains(index), "Concentration.chooseCard.index:\(index) = Not a valid index in cards array")
        if !cards[index].isMatched{
            if let matchIndex = oneAndOnlyOneCardFaceUp, matchIndex != index{
                //If cards match and only ONE card is FACEUP
                if cards[matchIndex] == cards[index] {
                    cards[matchIndex].isMatched = true
                    cards[index].isMatched = true
                    score += 2
                }else{
                    if cards[index].isTouched == 1 {
                        score -= 1
                    }else {
                        cards[index].isTouched = 1
                    }
                }
                cards[index].isFaceUp = true
            }else{
                //If NO card faceup or TWO cards face up
                oneAndOnlyOneCardFaceUp = index
            }
        }
        
    }
        
    func updateScoreValue() -> Int {
        return score
    }
}
extension Collection {
    var oneAndOnly : Element? {
        return count == 1 ? first : nil
    }
}