centurion/backend/src/Lobby.js

const User = require("./User.js");
const timeline = require("./timeline.js");

module.exports = class Lobby {
    /**
     * @type {User[]}
     */
    users = [];
    /**
     * @type {string|undefined}
     */
    leaderId = undefined;

    running = false;
    startTime = 0;
    currentSeconds = 0;
    timelineIndex = 0;

    // For debugging purposes
    speedFactor = 1;

    constructor(name) {
        this.name = name;
    }

    run(ioLobby) {
        this.running = true;
        this.startTime = Date.now();

        const doTick = () => {
            if (this.users.length === 0) {
                // this lobby is over.
                return;
            }


            const timestamp = timeline.getIndex(this.timelineIndex);
            const nextShot = timeline.getNextShot(this.timelineIndex);

            if (!timestamp) {
                // We are done.
                ioLobby.emit('tick_event', {
                    current: this.currentSeconds
                });
                console.log("Done");
                this.running = false;
                return;
            }

            console.log("ticking", this.currentSeconds);

            ioLobby.emit('tick_event', {
                current: this.currentSeconds,
                next: timestamp,
                nextShot: nextShot
            });

            if (this.currentSeconds >= timestamp.timestamp) {
                this.timelineIndex += 1;
            }

            this.currentSeconds += 1;
            // We spend some time processing, wait a bit less than 1000ms
            const nextTickTime = this.startTime + (1000 * this.currentSeconds / this.speedFactor);
            const waitTime = nextTickTime - Date.now();
            console.log("waiting", waitTime);
            setTimeout(doTick, Math.floor(waitTime / this.speedFactor));
        };

        if (false) {
            this.seek(ioLobby, 500);
        }

        doTick();
    }

    /**
     *
     * @param ioLobby
     * @param {number} time
     */
    seek(ioLobby, time) {
        this.currentSeconds = time;
        this.startTime = Date.now() - time * 1000;
        this.timelineIndex = timeline.indexForTime(this.currentSeconds);
        ioLobby.emit('seek', time);
    }

    /**
     *
     * @returns {boolean}
     */
    hasUsers() {
        return this.users.length !== 0;
    }


    setRandomLeader() {
        if (this.hasUsers()) {
            this.leaderId = this.users[0].id;
        }
    }

    /**
     *
     * @param {User} user
     */
    addUser(user) {
        this.users.push(user);
    }

    /**
     *
     * @param id
     * @returns {User|undefined}
     */
    getUser(id) {
        return this.users.find(u => u.id === id);
    }

    /**
     *
     * @param {string} id
     */
    removeUser(id) {
        this.users = this.users.filter(u => u.id !== id);
    }

    /**
     *
     * @returns {boolean}
     */
    hasLeader() {
        return !!this.leaderId;
    }

    /**
     *
     * @param {string} id
     * @returns {boolean}
     */
    isLeader(id) {
        return this.leaderId === id;
    }

    /**
     *
     * @param {string} id
     */
    setLeader(id) {
        if (!this.getUser(id)) {
            throw new Error('user_not_in_lobby');
        }

        this.leaderId = id;
    }

    /**
     *
     * @returns {User|undefined}
     */
    getLeader() {
        return this.users.find(u => u.id === this.leaderId)
    }
};