src/Tsugi.js

/**
 *  The Tsugi class/namespace/Utilities
 */
class Tsugi {

    // http://stackoverflow.com/questions/32647215/declaring-static-constants-in-es6-classes
    constructor() {
        /**
         * 
         */
        this.CONTEXT = "context_id";
        this.USER = "user_id";
        this.LINK = "link_id";
        this.ALL = "all";
        this.NONE = "none";
    }

    /**
     * Optionally handle launch and/or set up the LTI session and global variables
     *
     * This will set up as much of the $USER, $CONTEXT, $LINK,
     * and $RESULT data as it can including leaving them all null
     * if this is called on a request with no LTI launch and no LTI
     * data in the session.  This functions as and performs a
     * PHP session_start().
     *
     * @return Launch A Tsugi Launch object.
     */
    session_start(CFG) {
        return this.requireData(CFG, this.NONE);
    }

    /**
     * Handle launch and/or set up the LTI session and global variables
     *
     * Make sure we have the values we need in the LTI session
     * This routine will not start a session if none exists.  It will
     * die is there if no session_name() (PHPSESSID) cookie or
     * parameter.  No need to create any fresh sessions here.
     *
     * @param {Config} CFG A Tsugi Configuration object
     *
     * @param {*} needed Indicates which of
     * the data structures are needed. If this is omitted,
     * this assumes that CONTEXT, LINK, and USER data are required.
     * If NONE is present, then none of the three are rquired.
     * If some combination of the three are needed, this accepts
     * an array of the CONTEXT, LINK, and USER
     * can be passed in.
     * 
     * @return Launch A Tsugi Launch object.
     */
    requireData(CFG, needed=this.ALL) {
        if ( ! ( needed instanceof Array ) ) {
            needed = [ needed ];
        }
        console.log(needed);
        let ns = new Set(needed);
        console.log(ns.has("all"));
        let Launch = require('./Launch.js');
        let launch = new Launch(CFG);
        return launch;
    }

}

module.exports = Tsugi;