/*! Copyright (c) 2013 Brandon Aaron (http://brandon.aaron.sh)
 * Licensed under the MIT License (LICENSE.txt).
 *
 * Version 3.0.1
 *
 * Requires jQuery >= 1.2.6
 */

(function (factory) {
	if (typeof define === 'function' && define.amd) {
		// AMD. Register as an anonymous module.
		define( ['jquery'], factory );
	} else if (typeof exports === 'object') {
		// Node/CommonJS style for Browserify
		module.exports = factory;
	} else {
		// Browser globals
		factory( jQuery );
	}
}(function ($) {
	$.fn.bgiframe = function(s) {
		s = $.extend(
			{
				top         : 'auto', // auto == borderTopWidth
				left        : 'auto', // auto == borderLeftWidth
				width       : 'auto', // auto == offsetWidth
				height      : 'auto', // auto == offsetHeight
				opacity     : true,
				src         : 'javascript:false;',
				conditional : /MSIE 6\.0/.test( navigator.userAgent ) // expresion or function. return false to prevent iframe insertion
			},
			s
		);

		// wrap conditional in a function if it isn't already
		if ( ! $.isFunction( s.conditional )) {
			var condition = s.conditional;
			s.conditional = function() { return condition; };
		}

		var $iframe = $(
			'<iframe class="bgiframe"frameborder="0"tabindex="-1"src="' + s.src + '"' +
						   'style="display:block;position:absolute;z-index:-1;"/>'
		);

		return this.each(
			function() {
				var $this = $( this );
				if ( s.conditional( this ) === false ) {
					return; }
				var existing = $this.children( 'iframe.bgiframe' );
				var $el      = existing.length === 0 ? $iframe.clone() : existing;
				$el.css(
					{
						'top': s.top == 'auto' ?
						((parseInt( $this.css( 'borderTopWidth' ),10 ) || 0) * -1) + 'px' : prop( s.top ),
						'left': s.left == 'auto' ?
						((parseInt( $this.css( 'borderLeftWidth' ),10 ) || 0) * -1) + 'px' : prop( s.left ),
						'width': s.width == 'auto' ? (this.offsetWidth + 'px') : prop( s.width ),
						'height': s.height == 'auto' ? (this.offsetHeight + 'px') : prop( s.height ),
						'opacity': s.opacity === true ? 0 : undefined
					}
				);

				if ( existing.length === 0 ) {
					$this.prepend( $el );
				}
			}
		);
	};

	// old alias
	$.fn.bgIframe = $.fn.bgiframe;

	function prop(n) {
		return n && n.constructor === Number ? n + 'px' : n;
	}

}));
