function start() {
	if (!window['Msal']) {
		console.log('Disabling B2C authentication - The microsoft authentication library is not available.');
		generateBootstrapScript();
		return;
	}
	var authentication;
	var xhttp = new XMLHttpRequest();
	xhttp.onreadystatechange = function(){ //used instead of onload due to browser compatibility
		if (this.readyState === 4 && this.status === 200){
			var result = xhttp.responseText;
			try {
				var settings = JSON.parse(result);
			} catch (e) {
				var message = "Disabling B2C authentication - Unable to read the application settings json. \nMake sure that it is in valid json format (comments are not allowed).\n"
				console.log(message + e);
				generateBootstrapScript();
				return;
			}
			if (settings.authentication){
				authentication = settings.authentication;
			}
			if (authentication) {
				var msalConfig = {
					auth: {
						clientId: authentication.clientId,
						authority: authentication.authority,
						validateAuthority: false
					},
					cache: {
						cacheLocation: authentication.cacheLocation || "localStorage",
						storeAuthStateInCookie: true
					}
				}
				var instance = new Msal.UserAgentApplication(msalConfig);
				var tokenRequest = {
					scopes: authentication.b2cScopes,
					redirectUri: getRedirectUri(instance)
				}
				instance.handleRedirectCallback(redirectCallback);
				getToken(instance, tokenRequest);
			} else {
				console.log('Disabling B2C authentication - Could not find authentication object in application settings json. \nMake sure one exists to enable B2C authentication for the client.');
				generateBootstrapScript();
			}
		} else if (this.readyState === 4) {
			var message = "The request to " + xhttp.responseURL + " failed, responded with " + xhttp.status + ": " + xhttp.statusText + ".";
			console.log("Disabling B2C authentication - " + message);
			generateBootstrapScript();
		}
	}
	var domain = window.location.origin;
	var path = '/resources/application.settings.json';
	var url = domain + path;
	xhttp.open("GET", url, true);
	xhttp.send();
}

function redirectCallback(error, response) {
	var token = response.accessToken;
	if (!token && response.idToken) {
		getToken();
		return;
	}
	if (token) {
		generateBootstrapScript();
	}
}

function signIn(instance, tokenRequest) {
	instance.loginRedirect(tokenRequest);
}

function getToken(instance, tokenRequest) {
	if (!instance.getAccount()) {
		signIn(instance, tokenRequest);
		return;
	}

	return instance.acquireTokenSilent(tokenRequest)
		.then(handleTokenResponse)
		.catch(function (error) {
			handleTokenFailure(error, instance, tokenRequest)
		});
}

function handleTokenResponse(response) {
	generateBootstrapScript();
}

function handleTokenFailure(error, instance, tokenRequest) {
	if (error.message && error.message.startsWith('AADB2C90205')) {
		console.log('Disabling B2C authentication - Failed token acquisition', error);
		generateBootstrapScript(); 
	} else {
		if (requiresInteraction(error.errorCode)) {
			return signIn(instance, tokenRequest);
		} else {
			instance.acquireTokenRedirect(tokenRequest);
		}
	}
}

function requiresInteraction(errorCode) {
	if (!errorCode || !errorCode.length) {
		return false;
	}
	return errorCode === "consent_required" ||
		errorCode === "interaction_required" ||
		errorCode === "login_required";
}

function getRedirectUri(instance) {
	var redirectUri = instance.getRedirectUri();
	if (redirectUri.indexOf(('index.html')) > -1) {
		redirectUri = redirectUri.split('index.html')[0];
	}
	if (redirectUri.slice(-1) !== '/') {
		redirectUri += '/';
	}
	redirectUri = redirectUri + 'auth.html';
	return redirectUri;
}

function generateBootstrapScript() {
	var bootstrapScript = document.createElement('script');
	bootstrapScript.id = 'microloader';
	bootstrapScript.setAttribute('type', 'text/javascript');
	bootstrapScript.setAttribute('src', 'bootstrap.js');
	document.head.appendChild(bootstrapScript);
}

start();