/**
 * Allows text inputs to display a placeholder message until it gets focus, at which point the input
 * is set to empty.
 *
 * This simulated the placeholder attribute in html5.
 * http://dev.w3.org/html5/spec/Overview.html#the-placeholder-attribute
 *
 * @copyright Clock Limited 2010
 * @license http://opensource.org/licenses/bsd-license.php New BSD License
 * @author Paul Serby <paul.serby@clock.co.uk>
 */
(function ($) {
    $.fn.placeholder = function (text) {

        return this.each(function () {

            var
                context = $(this),
                placeholderText,
                nativePlaceholderSupport = ('placeholder' in document.createElement('input'));

            function onBlur(event) {
                checkIfEmpty($(event.target));
            }

            function checkIfEmpty() {
                if (context.val() === '') {
                    if (context.attr('type') === 'password') {
                        try {
                            context.attr('type', 'text');
                        } catch(e) {
                            return false;
                        }
                    }
                    context.val(placeholderText);
                    context.addClass('ui-placeholder');
                }
            }

            function onFocus(event) {
                context.removeClass('ui-placeholder');
                if (context.val() === placeholderText) {
                    context.val('');
                }
            }

            if (text === undefined) {
                placeholderText = $(this).attr('placeholder');
            } else {
                placeholderText = text;
            }

            if (!nativePlaceholderSupport) {
                checkIfEmpty(context.blur(onBlur).focus(onFocus));
                context.parents('form').submit(function(event) {
                    if (context.val() === placeholderText) {
                        context.val('');
                    }
                });
            } else {
                context.attr('placeholder', placeholderText);
            }
        });
    };
})(jQuery);