Luncher/server/src/routes/easterEggRoutes.ts

import express, { NextFunction } from "express";
import { getLogin } from "../auth";
import { parseToken } from "../utils";
import path from "path";
import fs from "fs";
import { EasterEgg } from "../../../types/gen/types.gen";

const EASTER_EGGS_JSON_PATH = path.join(__dirname, "../../.easter-eggs.json");
const IMAGES_PATH = '../../resources/easterEggs';

type EasterEggsJson = {
    [key: string]: EasterEgg[]
}

function generateUrl() {
    let result = '';
    const characters = 'abcdefghijklmnopqrstuvwxyz0123456789';
    const charactersLength = characters.length;
    let counter = 0;
    while (counter < 32) {
        result += characters.charAt(Math.floor(Math.random() * charactersLength));
        counter += 1;
    }
    return result;
}

/**
 * Vrátí náhodně jeden z definovaných easter egg obrázků pro přihlášeného uživatele.
 * 
 * @param req request
 * @param res response
 * @param next next
 * @returns náhodný easter egg obrázek, nebo 404 pokud žádný není definován
 */
function getEasterEggImage(req: any, res: any, next: NextFunction) {
    const login = getLogin(parseToken(req));
    try {
        if (login in easterEggs) {
            const imagePath = easterEggs[login][Math.floor(Math.random() * easterEggs[login].length)].path;
            res.sendFile(path.join(__dirname, IMAGES_PATH, imagePath));
            return;
        }
        res.sendStatus(404);
    } catch (e: any) { next(e) }
}

function getRandomPosition(startOffset: number, endOffset: number) {
    const choice = Math.floor(Math.random() * 4);

    if (choice === 0) {
        // Vlevo nahoře
        return {
            left: `${startOffset}px`,
            startLeft: `${startOffset}px`,
            "--start-left": `${startOffset}px`,
            top: `${startOffset}px`,
            startTop: `${startOffset}px`,
            "--start-top": `${startOffset}px`,
            endLeft: `${endOffset}px`,
            "--end-left": `${endOffset}px`,
            endTop: `${endOffset}px`,
            "--end-top": `${endOffset}px`,
            rotate: '135deg',
        }
    } else if (choice === 1) {
        // Vpravo nahoře
        return {
            right: `${startOffset}px`,
            startRight: `${startOffset}px`,
            "--start-right": `${startOffset}px`,
            top: `${startOffset}px`,
            startTop: `${startOffset}px`,
            "--start-top": `${startOffset}px`,
            endRight: `${endOffset}px`,
            "--end-right": `${endOffset}px`,
            endTop: `${endOffset}px`,
            "--end-top": `${endOffset}px`,
            rotate: '-135deg',
        }
    } else if (choice === 2) {
        // Vpravo dole
        return {
            right: `${startOffset}px`,
            startRight: `${startOffset}px`,
            "--start-right": `${startOffset}px`,
            bottom: `${startOffset}px`,
            startBottom: `${startOffset}px`,
            "--start-bottom": `${startOffset}px`,
            endRight: `${endOffset}px`,
            "--end-right": `${endOffset}px`,
            endBottom: `${endOffset}px`,
            "--end-bottom": `${endOffset}px`,
            rotate: '-45deg',
        }
    } else if (choice === 3) {
        // Vlevo dole
        return {
            left: `${startOffset}px`,
            startLeft: `${startOffset}px`,
            "--start-left": `${startOffset}px`,
            bottom: `${startOffset}px`,
            startBottom: `${startOffset}px`,
            "--start-bottom": `${startOffset}px`,
            endLeft: `${endOffset}px`,
            "--end-left": `${endOffset}px`,
            endBottom: `${endOffset}px`,
            "--end-bottom": `${endOffset}px`,
            rotate: '45deg',
        }
    }
}

const router = express.Router();

let easterEggs: EasterEggsJson;

// Registrace náhodných URL pro všechny existující easter eggy

if (fs.existsSync(EASTER_EGGS_JSON_PATH)) {
    const content = fs.readFileSync(EASTER_EGGS_JSON_PATH, 'utf-8');
    easterEggs = JSON.parse(content);
    for (const [_, eggs] of Object.entries(easterEggs)) {
        for (const easterEgg of eggs) {
            const url = generateUrl();
            easterEgg.url = url;
            router.get(`/${url}`, async (req, res, next) => {
                return getEasterEggImage(req, res, next);
            });
        }
    }
}

// Získání náhodného easter eggu pro přihlášeného uživatele
router.get("/", async (req, res, next) => {
    const login = getLogin(parseToken(req));
    try {
        if (easterEggs && login in easterEggs) {
            const randomEasterEgg = easterEggs[login][Math.floor(Math.random() * easterEggs[login].length)];
            const { path, startOffset, endOffset, ...strippedEasterEgg } = randomEasterEgg; // Path klient k ničemu nepotřebuje a nemá ho znát
            return res.status(200).json({ ...strippedEasterEgg, ...getRandomPosition(startOffset, endOffset) });
        }
        return res.status(200).send();
    } catch (e: any) { next(e) }
});

export default router;