function GridDS(options) {
	this.data = [];
	this.enablePaging = false;
	this.pageIndex = 0;
	this.pageSize = 10;
	this.sortBy = null;
	this.sortDirection = null;

	this.count = GridDS__count;
	this.numberOfPages = GridDS__numberOfPages;
	this.pageNumber = GridDS__pageNumber;
	this.gotoPage = GridDS__gotoPage;
	this.nextPage = GridDS__nextPage;
	this.previousPage = GridDS__previousPage;
	this.hasNextPage = GridDS__hasNextPage;
	this.hasPreviousPage = GridDS__hasPreviousPage;
	this.getData = GridDS__getData;
	this.sort = GridDS__sort;
	this.pages = GridDS__pages;

	if (options) {
		if (options.data) { this.data = options.data; }
		if (options.enablePaging) { this.enablePaging = options.enablePaging; }
		if (options.pageSize) { this.pageSize = options.pageSize; }
	}
}

function GridDS__count () {
	return this.data.length;
}

function GridDS__numberOfPages() {
	if (this.enablePaging == false) { return 1; }
	var p1 = this.data.length / this.pageSize;
	var p2 = Math.floor(p1);
	if (p1 == p2) { return p2; }
	return p2 + 1;
}

function GridDS__pageNumber() {
	if (this.enablePaging == false) { return 1; }
	return this.pageIndex + 1;
}

function GridDS__gotoPage(pageNumber) {
	if (this.enablePaging == false) { return; }
	if (pageNumber > 0 && pageNumber <= this.numberOfPages()) { this.pageIndex = pageNumber - 1; }
}

function GridDS__nextPage() {
	if (this.enablePaging == false) { return; }
	if (this.pageIndex < (this.numberOfPages() - 1)) { this.pageIndex++; }
}

function GridDS__previousPage() {
	if (this.enablePaging == false) { return; }
	if (this.pageIndex > 0) { this.pageIndex--; }
}

function GridDS__hasNextPage () {
	if (this.enablePaging == false) { return false; }
	if (this.pageIndex < (this.numberOfPages() - 1)) { return true; }
	return false;
}

function GridDS__hasPreviousPage () {
	if (this.enablePaging == false) { return false; }
	if (this.pageIndex > 0) { return true; }
	return false;
}

function GridDS__getData () {
	if (this.enablePaging == false) { return this.data; }

	var startIndex = this.pageIndex * this.pageSize;
	var endIndex = ((this.pageIndex + 1) * this.pageSize) - 1;
	if (endIndex > (this.data.length - 1)) { endIndex = this.data.length - 1; }

	var list = [];
	for (var i = startIndex; i <= endIndex; i++) {
		list.push(this.data[i]);
	}
	var pgs = [];
	for (var i = 1; i <= this.numberOfPages() ; i++) {
		pgs.push({ pageNumber: i });
	}
	return list;
}

function GridDS__sort (comparer) {
	this.data.sort(comparer);
	this.pageIndex = 0;
}

function GridDS__pages() {
	if (this.enablePaging == false) { return { pageNumber: 1 }; }
	var list = [];
	for (var i = 1; i <= this.numberOfPages() ; i++) {
		list.push({
			pageNumber: i
		});
	}
	return list;
}