import { Bean } from "./context/context";
import { Autowired } from "./context/context";

@Bean('templateService')
export class TemplateService {

    @Autowired('$scope') private $scope: any;

    private templateCache:any = {};
    private waitingCallbacks:any = {};

    // returns the template if it is loaded, or null if it is not loaded
    // but will call the callback when it is loaded
    getTemplate(url: any, callback: any) {

        const templateFromCache = this.templateCache[url];
        if (templateFromCache) {
            return templateFromCache;
        }

        let callbackList = this.waitingCallbacks[url];
        const that = this;
        if (!callbackList) {
            // first time this was called, so need a new list for callbacks
            callbackList = [];
            this.waitingCallbacks[url] = callbackList;
            // and also need to do the http request
            const client = new XMLHttpRequest();
            client.onload = function() {
                that.handleHttpResult(this, url);
            };
            client.open("GET", url);
            client.send();
        }

        // add this callback
        if (callback) {
            callbackList.push(callback);
        }

        // caller needs to wait for template to load, so return null
        return null;
    }

    handleHttpResult(httpResult: any, url: any) {

        if (httpResult.status !== 200 || httpResult.response === null) {
            console.warn(`Unable to get template error ${httpResult.status} - ${url}`);
            return;
        }

        // response success, so process it
        // in IE9 the response is in - responseText
        this.templateCache[url] = httpResult.response || httpResult.responseText;

        // inform all listeners that this is now in the cache
        const callbacks = this.waitingCallbacks[url];
        for (let i = 0; i < callbacks.length; i++) {
            const callback = callbacks[i];
            // we could pass the callback the response, however we know the client of this code
            // is the cell renderer, and it passes the 'cellRefresh' method in as the callback
            // which doesn't take any parameters.
            callback();
        }

        if (this.$scope) {
            const that = this;
            window.setTimeout(function() {
                that.$scope.$apply();
            }, 0);
        }
    }
}