@xpressit/winning-poker-hand-rank/src/index.ts

Determine winning poker hand rank

import { calcBestHand } from './calcBestHand';
import { toCard, toPlayingCard } from './card';
import { toCombination } from './toCombination';
import { Combination, GameType, PlayingCard } from './types';

type HandRank = {
    rank: number;
    combination: Combination;
    madeHand: [PlayingCard, PlayingCard, PlayingCard, PlayingCard, PlayingCard];
    unused: PlayingCard[];
    low?: {
        rank: number;
        madeHand: [PlayingCard, PlayingCard, PlayingCard, PlayingCard, PlayingCard];
    };
};

type PocketCards<T = GameType> = T extends 'omaha'
    ? [PlayingCard, PlayingCard, PlayingCard, PlayingCard]
    : [PlayingCard, PlayingCard];

const toOutputMadeHand = (madeHand: number[]) => {
    return madeHand.map((c) => toPlayingCard(c)) as [PlayingCard, PlayingCard, PlayingCard, PlayingCard, PlayingCard];
};

export const rankHands = <T extends GameType>(
    gameType: T,
    board: [PlayingCard, PlayingCard, PlayingCard, PlayingCard, PlayingCard],
    hands: PocketCards<T>[],
): HandRank[] => {
    return hands.map((hand) => {
        const bestHand = calcBestHand(
            gameType,
            hand.map((c) => toCard(c)),
            board.map((c) => toCard(c)),
        );

        return {
            rank: bestHand.rank,
            combination: toCombination(gameType, bestHand.rank),
            madeHand: toOutputMadeHand(bestHand.madeHand),
            unused: bestHand.unused.map((c) => toPlayingCard(c)),
            low: bestHand.low ? { rank: bestHand.low.rank, madeHand: toOutputMadeHand(bestHand.low.madeHand) } : undefined,
        };
    });
};