var isWebKit = document.childNodes && !document.all && !navigator.taintEnabled;

TYPO3BackendLogin = {

	/**
	 *  Initializing the Login Interface
	 */
	start: function() {
		TYPO3BackendLogin.preloadImages();
		TYPO3BackendLogin.registerEventListeners();
		TYPO3BackendLogin.setVisibilityOfClearIcon($('t3-username'), $('t3-username-clearIcon'));
		TYPO3BackendLogin.setVisibilityOfClearIcon($('t3-password'), $('t3-password-clearIcon'));
		TYPO3BackendLogin.checkForLogintypeCookie();
		TYPO3BackendLogin.checkForInterfaceCookie();
		$('t3-username').activate();
	},

	/**
	 * Preload the login process image, so it can show up immediatelly after submitting
	 */
	preloadImages: function() {
		var image = new Image();
		image.src = 'sysext/t3skin/icons/login-submit-progress.gif';
	},

	/**
	 * Registers listeners for the Login Interface (e.g. to toggle OpenID and Default login)
	 */
	registerEventListeners: function() {
		Event.observe(
				$('t3-login-switchToOpenId'),
				'click',
				TYPO3BackendLogin.switchToOpenId
			);
		Event.observe(
			$('t3-login-switchToDefault'),
			'click',
			TYPO3BackendLogin.switchToDefault
		);
		Event.observe(
			$('t3-login-submit'),
			'click',
			TYPO3BackendLogin.showLoginProcess
		);
		
			// The Interface selector is not always present, so this check is needed
		if (Object.isElement($('t3-interfaceselector'))) {
			TYPO3BackendLogin.observeEvents(
				$('t3-interfaceselector'),
				['change', 'blur'],
				TYPO3BackendLogin.interfaceSelectorChanged
			);
		}

		$A(['t3-username', 't3-password']).each(function(value) {
			Event.observe(
					$(value + '-clearIcon'),
					'click',
					function() { TYPO3BackendLogin.clearInputField($(value)); }
			);
			TYPO3BackendLogin.observeEvents(
					$(value),
					['focus', 'blur', 'keypress'],
					function() { TYPO3BackendLogin.setVisibilityOfClearIcon($(value), $(value + '-clearIcon')); }
			);
			if (!isWebKit) {
				Event.observe(
					$(value),
					'keypress',
					function(event) { TYPO3BackendLogin.showCapsLockWarning($(value + '-alert-capslock'), event); }
				);
			}
		})
	},

	/**
	 * Wrapper for Event.observe that takes an array with events, instead of only one event
	 */
	observeEvents: function(element, events, handler) {
		events.each(function(event) {
			Event.observe(
				element,
				event,
				handler
			);
		});
	},

	/**
	 * Shows up the clear icon for a field which is not empty, and hides it otherwise
	 */
	setVisibilityOfClearIcon: function(formField, clearIcon) {
		if (formField.value) {
			clearIcon.show();
		} else {
			clearIcon.hide();
		}
	},

	/**
	 * To prevent its unintented use when typing the password, the user is warned when Capslock is on
	 */
	showCapsLockWarning: function(alertIcon, event) {
		if (isCapslock(event)) {
			alertIcon.show();
		} else {
			alertIcon.hide();
		}
	},

	/**
	 * Clears an input field and sets focus to it
	 */
	clearInputField: function(formField) {
		formField.value = '';
		formField.focus();
	},

	/**
	 * Change to Interface for OpenId login and save the selection to a cookie
	 */
	switchToOpenId: function() {
		$('t3-login-label-username').hide();
		$('t3-login-label-openId').show();
		$('t3-login-openIdLogo').show();

		$('t3-login-form-footer-default').hide();
		$('t3-login-form-footer-openId').show();
		$('t3-login-password-section').hide();

		if ($('t3-login-interface-section')) {
			$('t3-login-interface-section').hide();
		}
		
		$('t3-username').activate();

		TYPO3BackendLogin.setLogintypeCookie('openid');
	},

	/**
	 * Change to Interface for default login and save the selection to a cookie
	 */
	switchToDefault: function() {
		$('t3-login-label-username').show();
		$('t3-login-label-openId').hide();
		$('t3-login-openIdLogo').hide();

		$('t3-login-form-footer-default').show();
		$('t3-login-form-footer-openId').hide();
		$('t3-login-password-section').show();

		if ($('t3-login-interface-section')) {
			$('t3-login-interface-section').show();
		}

		$('t3-username').activate();
		
		TYPO3BackendLogin.setLogintypeCookie('username');
	},
	
	/**
	 * Store a login type in a cookie to save it for future visits
	 * Login type means wether you login by username/password or OpenID
	 */
	setLogintypeCookie: function(type) {
		var now = new Date();
		var expires = new Date(now.getTime() + 1000*60*60*24*365); // cookie expires in one year
		document.cookie = 'typo3-login-method=' + type + '; expires=' + expires.toGMTString() + ';';
	},
	
	/**
	 * Check if a login type was stored in a cookie and change the Interface accordingly
	 */
	checkForLogintypeCookie: function() {
		if(document.cookie.indexOf('typo3-login-method=openid') >- 1) {
			TYPO3BackendLogin.switchToOpenId();
		}
	},
	
	/**
	 * Store the new selected Interface in a cookie to save it for future visits
	 */
	interfaceSelectorChanged: function(event) {
		var now = new Date();
		var expires = new Date(now.getTime() + 1000*60*60*24*365); // cookie expires in one year
		document.cookie = 'typo3-login-interface=' + $('t3-interfaceselector').getValue() + '; expires=' + expires.toGMTString() + ';'; 
	},
	
	/**
	 * Check if an interface was stored in a cookie and preselect it in the select box
	 */
	checkForInterfaceCookie: function() {
		if (Object.isElement($('t3-interfaceselector'))) {
			var posStart = document.cookie.indexOf('typo3-login-interface=');
			if (posStart != -1) {
				var selectedInterface = document.cookie.substr(posStart + 22);
				selectedInterface = selectedInterface.substr(0, selectedInterface.indexOf(';'));
			}
			$('t3-interfaceselector').setValue(selectedInterface);
		}
	},
	
	/**
	 * Hide all form fields and show a progress message and icon
	 */
	showLoginProcess: function() {
		if ($('t3-login-error')) {
			$('t3-login-error').hide();
		}

		$('t3-login-form-fields').hide();
		$('t3-nocookies-error').hide();

		// setting a fixed height (based on the current, calculated height of the browser) for 
		// the box with the login form, so it doesn't jump around when the spinner is shown
		var loginBoxHeight = $('t3-login-form-fields').getHeight();
		$('t3-login-process').setStyle({height: loginBoxHeight + 'px'}).show();
	}
};

Event.observe(window, 'load', TYPO3BackendLogin.start);
