muuhd/server/utils/messages.js

/**
 * Very bad logic error. Player must quit game, refresh page, and log in again.
 *
 * Client-->Server
 *      or
 * Server-->Client-->Plater
 */
export const CALAMITY = "calamity";

/** 
 * Tell recipient that an error has occurred 
 *
 * Server-->Client-->Player
 */
export const ERROR = "e";

/**
 * Message to be displayed.
 *
 * Server-->Client-->Player
 */
export const MESSAGE = "m";


/**
 * Player has entered data, and sends it to server.
 *
 * Player-->Client-->Server
 */
export const REPLY = "reply";

/**
 * Player wants to quit.
 *
 * Player-->Client-->Server
 */
export const QUIT = "quit";

/**
 * Player wants help
 *
 * Player-->Client-->Server
 */
export const HELP = "help";

/**
 * Server tells the client to prompt the player for some data
 *
 * Server-->Client-->Player
 */
export const PROMPT = "prompt";

/**
 * Player has entered a command, and wants to do something.
 *
 * Player-->Client-->Server
 */
export const COMMAND = "c";

/**
 * Server tells the client to prompt the player for some data
 *
 * Server-->Client-->Player
 */
export const SYSTEM = "_";

/**
 * Debug message, to be completely ignored in production
 *
 * Client-->Server
 *      or
 * Server-->Client-->Plater
 */
export const DEBUG = "dbg";

/**
 * Represents a message sent from client to server.
 */
export class ClientMessage {
    /**
     * @protected
     * @type {any[]} _arr The array that contains the message data
     */
    _attr;

    /** The message type.
     *
     * One of the * constants from this document.
     *
     * @returns {string}
     */
    get type() {
        return this._attr[0];
    }

    /**
     * @param {string} msgData the raw text data in the websocket message.
     */
    constructor(msgData) {
        if (typeof msgData !== "string") {
            throw new Error("Could not create client message. Attempting to parse json, but data was not even a string, it was a " + typeof msgData);
            return;
        }

        try {
            this._attr = JSON.parse(msgData);
        } catch (_) {
            throw new Error(`Could not create client message. Attempting to parse json, but data was invalid json: >>> ${msgData} <<<`);
        }

        if (!Array.isArray(this._attr)) {
            throw new Error(`Could not create client message. Excpected an array, but got a ${typeof this._attr}`);
        }

        if (this._attr.length < 1) {
            throw new Error("Could not create client message. Excpected an array with at least 1 element, but got an empty one");
        }
    }
    hasCommand() {
        return this._attr.length > 1 && this._attr[0] === COMMAND;
    }

    /** Does this message contain a username-response from the client? */
    isUsernameResponse() {
        return this._attr.length === 4
            && this._attr[0] === REPLY
            && this._attr[1] === "username"
            && typeof this._attr[2] === "string";
    }

    /** Does this message contain a password-response from the client? */
    isPasswordResponse() {
        return this._attr.length === 4 
            && this._attr[0] === REPLY 
            && this._attr[1] === "password"
            && typeof this._attr[2] === "string";
    }

    /** @returns {boolean} does this message indicate the player wants to quit */
    isQuitCommand() {
        return this._attr[0] === QUIT
    }

    isHelpCommand() {
        return this._attr[0] === HELP
    }

    /** @returns {boolean} is this a debug message? */
    isDebug() {
        return this._attr.length === 2 && this._attr[0] === DEBUG;
    }

    isIntegerResponse() {
        return this._attr.length === 4
            && this._attr[0] === REPLY
            && this._attr[1] === "integer"
            && (typeof this._attr[2] === "string" || typeof this._attr[2] === "number")
            && Number.isInteger(Number(this._attr[2]));
    }

    /** @returns {number} integer */
    get integer() {
        if (!this.isIntegerResponse()) {
            return undefined;
        }

        return Number.parseInt(this._attr[2]);
    }

    /** @returns {string|false} Get the username stored in this message */
    get username() {
        return this.isUsernameResponse() ? this._attr[2] : false;
    }

    /** @returns {string|false} Get the password stored in this message */
    get password() {
        return this.isPasswordResponse() ? this._attr[2] : false;
    }

    /** @returns {string} */
    get command() {
        return this.hasCommand() ? this._attr[1] : false;
    }
}

/**
 * Given a message type and some args, create a string that can be sent from the server to the client (or vise versa)
 *
 * @param {string} messageType
 * @param {...any} args
 */
export function prepare(messageType, ...args) {
    return JSON.stringify([messageType, ...args]);
}