Blackjack

Blackjack.swift

import Foundation

enum Card {
    case ace
    case face(value: Int)
    case jack
    case queen
    case king
}

extension Card: Equatable {
    
}

extension Card {
    func blackjackValue(aceHigh: Bool) -> Int {
        switch self {
        case .ace:
            return aceHigh ? 11 : 1
        case .face(let value):
            return value
        case .jack, .queen, .king:
            return 10
        }
    }
}

let standardDeck: [Card] = [.ace, .face(value: 2), .face(value: 3), .face(value: 4), .face(value: 5), .face(value: 6), .face(value: 7), .face(value: 8), .face(value: 9), .face(value: 10), .jack, .queen, .king, .ace, .face(value: 2), .face(value: 3), .face(value: 4), .face(value: 5), .face(value: 6), .face(value: 7), .face(value: 8), .face(value: 9), .face(value: 10), .jack, .queen, .king, .ace, .face(value: 2), .face(value: 3), .face(value: 4), .face(value: 5), .face(value: 6), .face(value: 7), .face(value: 8), .face(value: 9), .face(value: 10), .jack, .queen, .king, .ace, .face(value: 2), .face(value: 3), .face(value: 4), .face(value: 5), .face(value: 6), .face(value: 7), .face(value: 8), .face(value: 9), .face(value: 10), .jack, .queen, .king]

let allDecks: [Card] = standardDeck + standardDeck + standardDeck + standardDeck + standardDeck
var gameDeck: [Card] = []

func setup() {
    gameDeck = allDecks.shuffled()
}

struct Hand {
    private(set) var cards: [Card]
    var shown: Card {
        return cards.first!
    }
    var value: Int {
        return cards.reduce(0, { $0 + $1.blackjackValue(aceHigh: $0 + 11 >= 21) })
    }
    
    mutating func add(card: Card) {
        cards.append(card)
    }
    
    init(cards: [Card]) {
        self.cards = cards
    }
}

enum Result {
    case win
    case lose
    case tie
}

func deal(playerNumber: Int = 1) -> (dealer: Hand, players: [Hand]) {
    var playerHands: [Hand] = []
    for _ in 0..<playerNumber+1 {
        playerHands.append(Hand(cards: [gameDeck.removeFirst(), gameDeck.removeFirst()]))
    }
    return (dealer: playerHands.removeFirst(), players: playerHands)
}

func processDealerTurn(hand oldHand: Hand) -> Hand {
    let dealerStand = 17
    var hand = oldHand
    
    while hand.value >= 21 {
        if hand.value > dealerStand {
            break
        }
        hand.add(card: gameDeck.removeFirst())
    }
    
    return hand
}

func processPlayerTurn(hand oldHand: Hand, dealerCard: Card) -> Hand {
    let stand = 16
    var hand = oldHand
    
    while hand.value >= 21 {
        if hand.value > stand {
            break
        }
        if dealerCard.blackjackValue(aceHigh: true) >= 10 {
            break
        }
        hand.add(card: gameDeck.removeFirst())
    }
    
    return hand
}

func run() -> [Result] {
    var results: [Result] = []
    
    for _ in 0..<1000 {
        if gameDeck.count <= 10 {
            setup()
        }
        
        let (dealer, players) = deal()
        let player = players.first!
        
        if dealer.value == 21, dealer.value == player.value {
            results.append(.tie)
            continue
        } else if  dealer.value == 21 {
            results.append(.lose)
            continue
        } else if player.value == 21 {
            results.append(.win)
            continue
        }
        
        let playerTurn = processPlayerTurn(hand: player, dealerCard: dealer.shown)
        if playerTurn.value > 21 {
            results.append(.lose)
            continue
        }
        
        let dealerTurn = processDealerTurn(hand: dealer)
        if dealerTurn.value > 21 {
            results.append(.win)
            continue
        }
        
        if dealerTurn.value == playerTurn.value {
            results.append(.tie)
        } else if playerTurn.value > dealerTurn.value {
            results.append(.win)
        } else {
            results.append(.lose)
        }
    }
    return results
}

for i in 1...100 {
    setup()
    let results = run()
    let wins = results.filter { $0 == .win }.count
    let loses = results.filter { $0 == .lose }.count
    let ties = results.filter { $0 == .tie }.count
    
    print("\(i),\(wins),\(loses),\(ties)")
}