Simple Card Game

main.dart

import 'package:flutter/material.dart';

final Map<String, String> suitSymbols = {
  'd': '♦️',
  'h': '♥️',
  's': '♠️',
  'c': '♣️'
};

class Card {
  Card(this.suit, this.rank);

  final String suit;
  final int rank;

  final Map<int, String> rankNames = {
    11: 'Jack',
    12: 'Queen',
    13: 'King',
    1: 'Ace',
  };

  String get rankName => rankNames[rank] ?? '$rank';
  String get suitSymbol => suitSymbols[suit];

  @override
  String toString() {
    return '$rankName of $suitSymbol';
  }
}

class Deck {
  List<Card> cards = <Card>[];

  Deck() {
    final List<String> suits = suitSymbols.keys.toList();

    suits.forEach((String suit) {
      for (int rank = 1; rank <= 13; rank++) {
        cards.add(Card(suit, rank));
      }
    });
  }

  void shuffle() {
    cards.shuffle();
  }

  Card dealCard() {
    final Card topCard = cards.first;
    cards.remove(topCard);
    return topCard;
  }

  @override
  String toString() {
    return cards.map((Card card) => card).join(', ');
  }
}

// Entrypoint
void main() => runApp(SimpleCardGameApp());

class SimpleCardGameApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Simple Card Game',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
          primarySwatch: Colors.green, canvasColor: Colors.green[100]),
      home: GamePage(),
    );
  }
}

class GamePage extends StatefulWidget {
  @override
  _GamePageState createState() => _GamePageState();
}

class _GamePageState extends State<GamePage> {
  Deck deck;
  Card card1;
  Card card2;
  Card playerCard;
  bool isCovered;

  String message = '';

  @override
  void initState() {
    super.initState();
    newGame();
  }

  void newGame() {
    isCovered = true;
    playerCard = null;

    // Build New Deck
    deck = Deck();

    // Shuffle
    deck.shuffle();

    // Deal 2 cards;
    card1 = deck.dealCard();
    card2 = deck.dealCard();

    // Show message ready to play

    setState(() {
      message = 'Pick A Card!';
    });
  }

  void _onTap(Card selectedCard) {
    // get cpuCard
    final Card cpuCard = (card1 != selectedCard) ? card1 : card2;

    // compareCards

    setState(() {
      playerCard = selectedCard;
      isCovered = false;

      if (selectedCard.rank == cpuCard.rank) {
        message = 'It\'s a tie';
      } else if (selectedCard.rank > cpuCard.rank) {
        message = 'You won!';
      } else {
        message = 'CPU won!';
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Simple Card Game'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                CardWidget(
                  card: card1,
                  isCovered: isCovered,
                  onTap: _onTap,
                  isPlayerCard: playerCard == card1,
                ),
                CardWidget(
                  card: card2,
                  isCovered: isCovered,
                  onTap: _onTap,
                  isPlayerCard: playerCard == card2,
                ),
              ],
            ),
            Text(
              '$message',
              style: Theme.of(context).textTheme.headline4,
            ),
            (!isCovered)
                ? Container(
                    width: 200.0,
                    height: 44.0,
                    child: FlatButton(
                      shape: RoundedRectangleBorder(
                        borderRadius: BorderRadius.all(
                          Radius.circular(44.0),
                        ),
                      ),
                      color: Colors.red,
                      onPressed: () {
                        newGame();
                      },
                      child: Text(
                        'Play Again!',
                        style: TextStyle(
                          color: Colors.white,
                        ),
                      ),
                    ),
                  )
                : Container(
                    width: 200.0,
                    height: 44.0,
                  ),
          ],
        ),
      ),
    );
  }
}

class CardWidget extends StatelessWidget {
  CardWidget({this.card, this.isCovered, this.onTap, this.isPlayerCard});

  final Card card;
  final bool isCovered;
  final Function onTap;
  final bool isPlayerCard;

  Widget cover() {
    return Container(
      width: 80.0,
      height: 130.0,
      color: Colors.red,
    );
  }

  Widget cardFace() {
    return Container(
        child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Text(
          card.rankName,
          style: TextStyle(
            fontSize: 25,
          ),
        ),
        Text(
          card.suitSymbol,
          style: TextStyle(
            fontSize: 35,
          ),
        ),
      ],
    ));
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: isCovered
          ? () {
              onTap(card);
            }
          : null,
      child: Container(
        width: 100.0,
        height: 150.0,
        margin: EdgeInsets.all(10.0),
        padding: EdgeInsets.all(10.0),
        decoration: BoxDecoration(
          color: Colors.white,
          borderRadius: BorderRadius.all(
            Radius.circular(5),
          ),
          border: isPlayerCard
              ? Border.all(
                  color: Colors.lightGreen,
                  width: 5.0,
                )
              : null,
        ),
        child: isCovered ? cover() : cardFace(),
      ),
    );
  }
}