ecs-observable/examples/blackjack/main.ts

// ── Blackjack: BT-driven game loop with command-based input ──
//
// Architecture:
//   Behaviour Tree (buildTree) — controls game flow:
//     root (repeat)
//       └── seq (sequential)
//             ├── handleInput (leaf)     — reads queued commands, mutates state
//             ├── dealerPlay (leaf)      — auto-plays dealer hand on dealerTurn
//             └── render (leaf)          — draws via blessed
//
//   CommandQueue — processes input:
//     Keyboard → spawn command entities → CommandQueue.execute()
//     → handlers mutate game state
//
//   Cards as entities with tag components:
//     Each card is an entity with a Card component ({ rank, suit, order }).
//     Tag components (InDeck, InPlayerHand, InDealerHand) mark which
//     collection the card belongs to. Queries find cards by tag.
//     Order is tracked via the `order` field on Card.
//
// Usage:
//   npx tsx examples/blackjack/main.ts

import { World } from "../../src/index";
import { query } from "../../src/query";
import { buildTree } from "../../src/bt/index";
import { CommandQueue } from "../../src/commands/index";

import {
  Card,
  InDeck,
  InPlayerHand,
  InDealerHand,
  HoleHidden,
  Score,
  Bet,
  GamePhase,
} from "./components";

import { Hit, Stand, NewRound, BetMore, BetLess } from "./commands";

import {
  SUITS,
  RANKS,
  handValue,
  isBust,
  isBlackjack,
  dealerShouldHit,
  determineOutcome,
  payout,
  type CardData,
} from "./game";

import { createUI, render } from "./render";
import { startInput, type Key } from "./input";

// ── Setup ────────────────────────────────────────────
const world = new World();

// Singleton game state
world.addSingleton(Score);
world.addSingleton(Bet);
world.addSingleton(GamePhase);

// Create blessed UI
const ui = createUI();

// ── Card helpers (tag-based) ─────────────────────────

/** Create all 52 card entities with the InDeck tag. */
function buildDeck(): void {
  let order = 0;
  for (const suit of SUITS) {
    for (const rank of RANKS) {
      const e = world.spawn();
      world.add(e, Card, { rank, suit, order });
      world.add(e, InDeck);
      order++;
    }
  }
}

/** Shuffle the deck: collect all InDeck entities, shuffle, reassign order. */
function shuffleDeck(): void {
  const entities = [...world.query(query(Card, InDeck))];
  // Fisher-Yates shuffle
  for (let i = entities.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [entities[i], entities[j]] = [entities[j], entities[i]];
  }
  // Reassign order to match shuffled position
  for (let i = 0; i < entities.length; i++) {
    world.get(entities[i], Card).order = i;
  }
}

/** Draw the top card from the deck (highest order). Returns entity or null. */
function drawCard(): number | null {
  const cards = [...world.query(query(Card, InDeck))];
  if (cards.length === 0) return null;
  // Find the one with the highest order
  let top = cards[0];
  let topOrder = world.get(top, Card).order;
  for (let i = 1; i < cards.length; i++) {
    const o = world.get(cards[i], Card).order;
    if (o > topOrder) {
      top = cards[i];
      topOrder = o;
    }
  }
  world.remove(top, InDeck);
  return top;
}

/** Move a card entity to a hand tag, assigning the next order. */
function dealTo(cardEntity: number, tag: typeof InPlayerHand): void {
  const existing = [...world.query(query(Card, tag))];
  const nextOrder =
    existing.length === 0
      ? 0
      : Math.max(...existing.map((e) => world.get(e, Card).order)) + 1;
  world.add(cardEntity, tag);
  world.get(cardEntity, Card).order = nextOrder;
}

/** Collect CardData from a hand tag, sorted by order. */
function getHand(tag: typeof InPlayerHand): CardData[] {
  return [...world.query(query(Card, tag))]
    .map((e) => {
      const c = world.get(e, Card);
      return { rank: c.rank, suit: c.suit, order: c.order };
    })
    .sort((a, b) => a.order - b.order)
    .map(({ rank, suit }) => ({ rank, suit }));
}

/** Remove all cards from a hand tag (destroy the card entities). */
function clearHand(tag: typeof InPlayerHand): void {
  for (const e of world.query(query(Card, tag))) {
    world.destroy(e);
  }
}

/** Count cards remaining in the deck. */
function deckCount(): number {
  return [...world.query(query(Card, InDeck))].length;
}

// ── Game flow ────────────────────────────────────────

function dealInitial(): void {
  const c1 = drawCard();
  const c2 = drawCard();
  const c3 = drawCard();
  const c4 = drawCard();
  if (c1) dealTo(c1, InPlayerHand);
  if (c2) dealTo(c2, InDealerHand);
  if (c3) dealTo(c3, InPlayerHand);
  if (c4) dealTo(c4, InDealerHand);
}

function startRound(): void {
  const bet = world.getSingleton(Bet);
  const score = world.getSingleton(Score);

  // Deduct bet
  score.chips -= bet.amount;

  // Re-shuffle if deck is low
  if (deckCount() < 15) {
    // Move all remaining InDeck cards back, then shuffle
    const remaining = [...world.query(query(Card, InDeck))];
    for (const e of remaining) {
      world.remove(e, InDeck);
    }
    for (const e of remaining) {
      world.add(e, InDeck);
    }
    shuffleDeck();
  }

  // Clear old hands
  clearHand(InPlayerHand);
  clearHand(InDealerHand);
  world.removeSingleton(HoleHidden);

  dealInitial();

  // Check for natural blackjack
  const playerCards = getHand(InPlayerHand);
  const dealerCards = getHand(InDealerHand);

  if (isBlackjack(playerCards)) {
    world.removeSingleton(HoleHidden);

    if (isBlackjack(dealerCards)) {
      score.chips += bet.amount;
      score.pushes++;
      world.setSingleton(GamePhase, {
        phase: "roundOver",
        message: "Both have Blackjack — Push! Press N for new round.",
      });
    } else {
      const winnings = payout("blackjack", bet.amount);
      score.chips += bet.amount + winnings;
      score.wins++;
      world.setSingleton(GamePhase, {
        phase: "roundOver",
        message: "Blackjack! You win 3:2! Press N for new round.",
      });
    }
  } else {
    world.addSingleton(HoleHidden);
    world.setSingleton(GamePhase, {
      phase: "playerTurn",
      message: "Your turn — H to hit, S to stand.",
    });
  }
}

function resolveRound(): void {
  const playerCards = getHand(InPlayerHand);
  const dealerCards = getHand(InDealerHand);
  const score = world.getSingleton(Score);
  const bet = world.getSingleton(Bet);

  const outcome = determineOutcome(playerCards, dealerCards);
  const winnings = payout(outcome, bet.amount);

  score.chips += bet.amount + winnings;

  switch (outcome) {
    case "blackjack":
    case "win":
      score.wins++;
      break;
    case "lose":
      score.losses++;
      break;
    case "push":
      score.pushes++;
      break;
  }

  const messages: Record<string, string> = {
    win: "You win!",
    lose: "Dealer wins.",
    push: "Push — tie!",
    blackjack: "Blackjack! You win 3:2!",
  };

  world.setSingleton(GamePhase, {
    phase: "roundOver",
    message: `${messages[outcome]} Press N for new round.`,
  });
}

// ── Command handlers ─────────────────────────────────
const commands = new CommandQueue(world);

commands.handle(Hit, () => {
  const phase = world.getSingleton(GamePhase);
  if (phase.phase !== "playerTurn") return;

  const cardEntity = drawCard();
  if (cardEntity) {
    dealTo(cardEntity, InPlayerHand);
  }

  if (isBust(getHand(InPlayerHand))) {
    world.removeSingleton(HoleHidden);
    resolveRound();
  }
});

commands.handle(Stand, () => {
  const phase = world.getSingleton(GamePhase);
  if (phase.phase !== "playerTurn") return;

  world.removeSingleton(HoleHidden);
  world.setSingleton(GamePhase, {
    phase: "dealerTurn",
    message: "Dealer's turn...",
  });
});

commands.handle(NewRound, () => {
  const phase = world.getSingleton(GamePhase);
  if (phase.phase !== "roundOver" && phase.phase !== "betting") return;

  const score = world.getSingleton(Score);
  if (score.chips <= 0) {
    world.setSingleton(GamePhase, {
      phase: "roundOver",
      message: "You're out of chips! Restart the program to play again.",
    });
    return;
  }

  startRound();
});

commands.handle(BetMore, () => {
  const phase = world.getSingleton(GamePhase);
  if (phase.phase !== "betting" && phase.phase !== "roundOver") return;

  const bet = world.getSingleton(Bet);
  const score = world.getSingleton(Score);
  bet.amount = Math.min(bet.amount + 10, score.chips);
});

commands.handle(BetLess, () => {
  const phase = world.getSingleton(GamePhase);
  if (phase.phase !== "betting" && phase.phase !== "roundOver") return;

  const bet = world.getSingleton(Bet);
  bet.amount = Math.max(bet.amount - 10, 10);
});

// ── Behaviour Tree ───────────────────────────────────
const runner = buildTree(world, {
  kind: "repeat",
  child: {
    kind: "sequential",
    children: [
      {
        kind: "leaf",
        run: () => {
          commands.execute();
        },
      },
      {
        kind: "leaf",
        *run() {
          while (true) {
            const dt: number = yield;
            const phase = world.getSingleton(GamePhase);
            if (phase.phase !== "dealerTurn") continue;

            if (dealerShouldHit(getHand(InDealerHand))) {
              const cardEntity = drawCard();
              if (cardEntity) {
                dealTo(cardEntity, InDealerHand);
              }
            } else {
              resolveRound();
            }
          }
        },
      },
      {
        kind: "leaf",
        run: () => {
          render(world, ui);
        },
      },
    ],
  },
});

// ── Input → Command mapping ──────────────────────────
const keyToCommand: Partial<Record<Key, typeof Hit>> = {
  h: Hit,
  s: Stand,
  n: NewRound,
  up: BetMore,
  down: BetLess,
};

startInput(ui.screen, (key) => {
  const cmd = keyToCommand[key];
  if (cmd) {
    const cmdEntity = world.spawn();
    world.add(cmdEntity, cmd);
  }
});

// ── Game loop ────────────────────────────────────────
world.setSingleton(GamePhase, {
  phase: "betting",
  message: "Welcome to Blackjack! Press N to start.",
});

buildDeck();
shuffleDeck();
runner.schedule((runner as any).root);

const TICK_MS = 16;
const interval = setInterval(() => {
  runner.tick(TICK_MS);
}, TICK_MS);

process.on("SIGINT", () => {
  clearInterval(interval);
  ui.screen.destroy();
  process.exit(0);
});