console.info("cursor");

// 为div保存range

var _range = null;

function displayAreaFocusAndBlur() {

	// 如果有保存的焦点则重新获取到该焦点，如果没有保存的焦点则以文本最后为该焦点

	$('#displayArea').on('focus', function(ev) {

		var selection = window.getSelection();

		if (selection && _range) {

			selection.removeAllRanges();

			selection.addRange(_range); // 添加焦点

		} else {

			var displayArea = document.getElementById('displayArea');

			cursorManager.setEndOfContenteditable(displayArea);

		}

	});

	// 保存焦点到_range

	$('#displayArea').on('blur', function() {

		var selection = window.getSelection();

		if (selection && selection.rangeCount > 0) {

			_range = selection.getRangeAt(0).cloneRange();

		}

	});

}



// 保证focus时，光标定位到元素的最后面

// Namespace management idea from

// http://enterprisejquery.com/2010/10/how-good-c-habits-can-encourage-bad-javascript-habits-part-1/

function cursorManage(cursorManager) {

	// From: http://www.w3.org/TR/html-markup/syntax.html#syntax-elements

	var voidNodeTags = [ 'AREA', 'BASE', 'BR', 'COL', 'EMBED', 'HR', 'IMG',

			'INPUT', 'KEYGEN', 'LINK', 'MENUITEM', 'META', 'PARAM', 'SOURCE',

			'TRACK', 'WBR', 'BASEFONT', 'BGSOUND', 'FRAME', 'ISINDEX' ];

	// From:

	// http://stackoverflow.com/questions/237104/array-containsobj-in-javascript

	Array.prototype.contains = function(obj) {

		var i = this.length;

		while (i--) {

			if (this[i] === obj) {

				return true;

			}

		}

		return false;

	}

	// Basic idea from:

	// http://stackoverflow.com/questions/19790442/test-if-an-element-can-contain-text

	function canContainText(node) {

		if (node.nodeType == 1) { // is an element node

			return !voidNodeTags.contains(node.nodeName);

		} else { // is not an element node

			return false;

		}

	}

	function getLastChildElement(el) {

		var lc = el.lastChild;

		while (lc && lc.nodeType != 1) {

			if (lc.previousSibling)

				lc = lc.previousSibling;

			else

				break;

		}

		return lc;

	}

	// Based on Nico Burns's answer

	cursorManager.setEndOfContenteditable = function(contentEditableElement) {

		while (getLastChildElement(contentEditableElement)

				&& canContainText(getLastChildElement(contentEditableElement))) {

			contentEditableElement = getLastChildElement(contentEditableElement);

		}

		var range, selection;

		if (document.createRange) // Firefox, Chrome, Opera, Safari, IE 9+

		{

			range = document.createRange(); // Create a range (a range is a like

			// the selection but invisible)

			range.selectNodeContents(contentEditableElement); // Select the

			// entire

			// contents of

			// the element

			// with the

			// range

			range.collapse(false); // collapse the range to the end point.

			// false means collapse to end rather than

			// the start

			selection = window.getSelection(); // get the selection object

			// (allows you to change

			// selection)

			selection.removeAllRanges(); // remove any selections already

			// made

			_range = range.cloneRange();

			selection.addRange(range); // make the range you have just created

			// the visible selection

		} else if (document.selection) // IE 8 and lower

		{

			range = document.body.createTextRange(); // Create a range (a

			// range is a like the

			// selection but

			// invisible)

			range.moveToElementText(contentEditableElement); // Select the

			// entire

			// contents of

			// the element

			// with the

			// range

			range.collapse(false); // collapse the range to the end point.

			// false means collapse to end rather than

			// the start

			range.select(); // Select the range (make it the visible selection

		}

	}

	cursorManager.setEndOfRange = function(range) {

		if (document.createRange) {

			range.collapse(false);

			selection = window.getSelection();

			selection.removeAllRanges();

			_range = range.cloneRange();

			selection.addRange(range);

		}

	}

}