(function () {

    var entityID;
    var codes = {};
    var GOOGLE_SCRIPTS_URL = "https://script.google.com/macros/s/AKfycbz9iifQui3XTCqHemf9x1CKZEffx3f7ONdVzb4YK_OtTv7cvw/exec";
    
    // GOOGLE SHEET FUNCTIONS
    function startFetchCode(onCompleteCallback, onErrorCallback) {

        var params = "";
        var onComplete = onCompleteCallback;
        var onError = onErrorCallback;

        sendRequest(GOOGLE_SCRIPTS_URL, params, onComplete, onError);
    }

    function sendRequest(url, paramString, onComplete, onError) {

        var request = new XMLHttpRequest();
        var requestURL = paramString
            ? url + "?" + paramString
            : url;

        // print("SENT PARAMS");
        // print(requestURL);

        request.open('GET', requestURL);
        request.timeout = 10000;
        request.ontimeout = onError;
        request.onreadystatechange = function () { // called after load when readyState = 4
            if (request.readyState === 4) {
                if (onComplete) {
                    onComplete(request);
                }
            }
        };
        request.send();

    }

    function encodeURLParams(params) {
        var paramPairs = [];
        for (var key in params) {
            paramPairs.push(key + "=" + params[key]);
        }
        return paramPairs.join("&");
    }

    function CodeGetter () {};

    CodeGetter.prototype = {
        remotelyCallable: [
            "getCode"
        ],

        preload: function (id) {
            entityID = id;
        },

        getRequestCallbacks: function (sessionUUID, username) {
            var _this = this;
            var uuid = sessionUUID;

            var onCompleteCallback = function (request) {

                print("recieved code ", request.responseText);
                print("uuid", uuid);

                // get code
                var code;
                try {
                    code = request.responseText;
                } catch (e) {
                    console.error("Error getting code");
                }

                // set username to the code
                codes[username] = code;

                _this.returnCode(uuid, code);
            }

            var onErrorCallback = function () {
                _this.returnError(uuid);
            }

            return [
                onCompleteCallback,
                onErrorCallback
            ];
        },

        // params [ sessionUUID, username ]
        getCode: function (id, params) {

            var sessionUUID = params[0];
            var username = params[1];

            if (codes[username]) {
                this.returnCode(codes[username]);
            } else {
                var callbacks = this.getRequestCallbacks(sessionUUID, username);

                var onComplete = callbacks[0];
                var onError = callbacks[1];

                startFetchCode(onComplete, onError);
            }
        },

        returnError: function (uuid) {

            print("error", uuid);
            Entities.callEntityClientMethod(
                uuid, 
                entityID, 
                "displayError"
            );
        },

        returnCode: function (uuid, code) {

            print("returning code", uuid, code, entityID);
            Entities.callEntityClientMethod(
                uuid, 
                entityID, 
                "displayCode",
                [code]
            );
        }

    }

    return new CodeGetter();

});