/*
 * MBP - Mobile boilerplate helper functions
 */
(function(document){

	window.MBP = window.MBP || {};

	// Fix for iPhone viewport scale bug
	// http://www.blog.highub.com/mobile-2/a-fix-for-iphone-viewport-scale-bug/

	MBP.viewportmeta = document.querySelector && document.querySelector('meta[name="viewport"]');
	MBP.ua = navigator.userAgent;

	MBP.scaleFix = function () {
		if (MBP.viewportmeta && /iPhone|iPad/.test(MBP.ua) && !/Opera Mini/.test(MBP.ua)) {
			MBP.viewportmeta.content = "width=device-width, minimum-scale=1.0, maximum-scale=1.0";
			document.addEventListener("gesturestart", MBP.gestureStart, false);
		}
	};
	MBP.gestureStart = function () {
		MBP.viewportmeta.content = "width=device-width, minimum-scale=0.25, maximum-scale=1.6";
	};


	// Hide URL Bar for iOS
	// http://remysharp.com/2010/08/05/doing-it-right-skipping-the-iphone-url-bar/

	MBP.hideUrlBar = function () {
		/iPhone/.test(MBP.ua) && !pageYOffset && !location.hash && setTimeout(function () {
		  window.scrollTo(0, 1);
		}, 1000);
	};


	// Fast Buttons - read wiki below before using
	// https://github.com/shichuan/mobile-html5-boilerplate/wiki/JavaScript-Helper

	MBP.fastButton = function (element, handler) {
		this.element = element;
		this.handler = handler;
		if (element.addEventListener) {
		  element.addEventListener('touchstart', this, false);
		  element.addEventListener('click', this, false);
		}
	};

	MBP.fastButton.prototype.handleEvent = function(event) {
		switch (event.type) {
			case 'touchstart': this.onTouchStart(event); break;
			case 'touchmove': this.onTouchMove(event); break;
			case 'touchend': this.onClick(event); break;
			case 'click': this.onClick(event); break;
		}
	};

	MBP.fastButton.prototype.onTouchStart = function(event) {
		event.stopPropagation();
		this.element.addEventListener('touchend', this, false);
		document.body.addEventListener('touchmove', this, false);
		this.startX = event.touches[0].clientX;
		this.startY = event.touches[0].clientY;
		this.element.style.backgroundColor = "rgba(0,0,0,.7)";
	};

	MBP.fastButton.prototype.onTouchMove = function(event) {
		if(Math.abs(event.touches[0].clientX - this.startX) > 10 || Math.abs(event.touches[0].clientY - this.startY) > 10) {
			this.reset();
		}
	};

	MBP.fastButton.prototype.onClick = function(event) {
		event.stopPropagation();
		this.reset();
		this.handler(event);
		if(event.type == 'touchend') {
			MBP.preventGhostClick(this.startX, this.startY);
		}
		this.element.style.backgroundColor = "";
	};

	MBP.fastButton.prototype.reset = function() {
		this.element.removeEventListener('touchend', this, false);
		document.body.removeEventListener('touchmove', this, false);
		this.element.style.backgroundColor = "";
	};

	MBP.preventGhostClick = function (x, y) {
		MBP.coords.push(x, y);
		window.setTimeout(function (){
			MBP.coords.splice(0, 2);
		}, 2500);
	};

	MBP.ghostClickHandler = function (event) {
		for(var i = 0, len = MBP.coords.length; i < len; i += 2) {
			var x = MBP.coords[i];
			var y = MBP.coords[i + 1];
			if(Math.abs(event.clientX - x) < 25 && Math.abs(event.clientY - y) < 25) {
				event.stopPropagation();
				event.preventDefault();
			}
		}
	};

	if (document.addEventListener) {
		document.addEventListener('click', MBP.ghostClickHandler, true);
	}

	MBP.coords = [];


	// iOS Startup Image
	// https://github.com/shichuan/mobile-html5-boilerplate/issues#issue/2

	MBP.splash = function () {
		var filename = navigator.platform === 'iPad' ? 'h/' : 'l/';
		document.write('<link rel="apple-touch-startup-image" href="/img/' + filename + 'splash.png" />' );
	};


	// Autogrow
	// http://googlecode.blogspot.com/2009/07/gmail-for-mobile-html5-series.html

	MBP.autogrow = function (element, lh) {

		function handler(e){
			var newHeight = this.scrollHeight,
				currentHeight = this.clientHeight;
			if (newHeight > currentHeight) {
				this.style.height = newHeight + 3 * textLineHeight + "px";
			}
		}

		var setLineHeight = (lh) ? lh : 12,
			textLineHeight = element.currentStyle ? element.currentStyle.lineHeight :
							 getComputedStyle(element, null).lineHeight;

		textLineHeight = (textLineHeight.indexOf("px") == -1) ? setLineHeight :
						 parseInt(textLineHeight, 10);

		element.style.overflow = "hidden";
		element.addEventListener ? element.addEventListener('keyup', handler, false) :
								   element.attachEvent('onkeyup', handler);
	};

})(document);