@opentarot/core/src/deck-data/draws.ts

A typescript interface for the open tarot ecosystem.

// Basic random card draw methods.

import { mapIntToCardName } from './cards';

export interface CardDraw {
    principal: string;
    timestamp: number;
    card: number;
    cardName: string;
    upsidedown: boolean;
    message: string;
}

export default async function drawCard(principal: string): Promise<CardDraw> {
    const timestamp = new Date().getTime();
    const [F_CARD, F_UPSIDEDOWN] = allowAdminForcedDraw();
    const card = F_CARD === undefined ? randomCardIndex() : F_CARD;
    const cardName = mapIntToCardName(card);
    const upsidedown =
        F_UPSIDEDOWN === undefined ? Math.random() >= 0.66 : F_UPSIDEDOWN;
    const message = `Drew ${cardName} ${
        upsidedown ? 'up-side-down' : 'right-side-up'
    } (${card})`;
    console.info(message);
    return { principal, timestamp, card, cardName, upsidedown, message };
}

export function randomCardIndex() {
    return getRandomInt(0, 77);
}

interface window {
    FORCE_NEXT_DRAW?: [number | undefined, boolean | undefined];
}

function allowAdminForcedDraw(): [number | undefined, boolean | undefined] {
    const global = window as window;
    const [F_CARD, F_UPSIDEDOWN] = global?.FORCE_NEXT_DRAW || [
        undefined,
        undefined,
    ];
    global.FORCE_NEXT_DRAW = undefined;
    return [F_CARD, F_UPSIDEDOWN];
}

function getRandomInt(min: number, max: number) {
    min = Math.ceil(min);
    max = Math.floor(max);
    return Math.floor(Math.random() * (max - min + 1)) + min;
}