converse.js/src/headless/shared/rsm.js

Browser based XMPP chat client

/**
 * @copyright The Converse.js contributors
 * @license Mozilla Public License (MPLv2)
 * @description XEP-0059 Result Set Management
 *   Some code taken from the Strophe RSM plugin, licensed under the MIT License
 *   Copyright 2006-2017 Strophe (https://github.com/strophe/strophejs)
 */
import { isUndefined } from "../utils/object.js";
import converse from "./api/public.js";

const { Strophe, $build } = converse.env;

Strophe.addNamespace("RSM", "http://jabber.org/protocol/rsm");

const RSM_QUERY_PARAMETERS = ["after", "before", "index", "max"];

const toNumber = (v) => Number(v);
const toString = (v) => v.toString();

export const RSM_TYPES = {
    after: toString,
    before: toString,
    count: toNumber,
    first: toString,
    index: toNumber,
    last: toString,
    max: toNumber,
};

// This array contains both query attributes and response attributes
export const RSM_ATTRIBUTES = Object.keys(RSM_TYPES);

/**
 * Instances of this class are used to page through query results according to XEP-0059 Result Set Management
 * @class RSM
 */
export class RSM {
    static getQueryParameters(options = {}) {
        return RSM_QUERY_PARAMETERS.reduce((result, key) => {
            if (options[key] !== undefined) {
                result[key] = options[key];
            }
            return result;
        }, {});
    }

    static parseXMLResult(set) {
        const result = {};
        for (var i = 0; i < RSM_ATTRIBUTES.length; i++) {
            const attr = RSM_ATTRIBUTES[i];
            const elem = set.getElementsByTagName(attr)[0];
            if (!isUndefined(elem) && elem !== null) {
                result[attr] = RSM_TYPES[attr](Strophe.getText(elem));
                if (attr == "first") {
                    result.index = RSM_TYPES["index"](elem.getAttribute("index"));
                }
            }
        }
        return result;
    }

    /**
     * Creates a new RSM instance
     * @param { Object } options - Configuration options
     */
    constructor(options = {}) {
        this.query = RSM.getQueryParameters(options);
        this.result = options.xml ? RSM.parseXMLResult(options.xml) : {};
    }

    /**
     * Returns a `<set>` XML element that confirms to XEP-0059 Result Set Management.
     * The element is constructed based on the RSMQueryOptions
     * that are set on this RSM instance.
     * @returns {Element}
     */
    toXML() {
        const xml = $build("set", { xmlns: Strophe.NS.RSM });
        const reducer = (xml, a) =>
            !isUndefined(this.query[a])
                ? xml
                      .c(a)
                      .t((this.query[a] || "").toString())
                      .up()
                : xml;
        return RSM_QUERY_PARAMETERS.reduce(reducer, xml).tree();
    }

    /**
     * Returns a string representation of the result-set XML
     * @returns {string}
     */
    toString() {
        return Strophe.serialize(this.toXML());
    }

    /**
     * @param {string} max
     * @param {string} before
     */
    next(max, before) {
        const options = Object.assign({}, this.query, { after: this.result.last, before, max });
        return new RSM(options);
    }

    /**
     * @param {string} max
     * @param {string} after
     */
    previous(max, after) {
        const options = Object.assign({}, this.query, { after, before: this.result.first, max });
        return new RSM(options);
    }
}