//
// Fetch the PDF document from the URL using promises
//
var pdfDoc: PDFDocumentProxy;
var pageNum: number;

PDFJS.getDocument('helloworld.pdf').then(function (pdf) {
	// Using promise to fetch the page
	pdfDoc = pdf;
	pageNum = 1;
	renderPage(pageNum);
});

function renderPage(pageNum: number) {
	pdfDoc.getPage(pageNum).then(function (page) {
		var scale = 1.5;
		var viewport = page.getViewport(scale);

		//
		// Prepare canvas using PDF page dimensions
		//
		var canvas = <HTMLCanvasElement>document.getElementById('the-canvas');
		var context = canvas.getContext('2d');
		canvas.height = viewport.height;
		canvas.width = viewport.width;
		
		//
		// test viewport conversion methods
		// convertToViewportRectangle and normalizeRect are used in the acroforms example:
		// https://github.com/mozilla/pdf.js/blob/master/examples/acroforms/forms.js
		//
		const rect = viewport.convertToViewportRectangle([100,100,0,0]);
		const normalizedRect = PDFJS.Util.normalizeRect(rect);
		const point = viewport.convertToViewportPoint(100, 100);
		const pdfPoint = viewport.convertToPdfPoint(100, 100);

		//
		// Render PDF page into canvas context
		//
		var renderContext = {
			canvasContext: context,
			viewport: viewport
		};
		page.render(renderContext);
	});
}

function goNext() {
    if (pdfDoc && pageNum < pdfDoc.numPages) {
        ++pageNum;
        renderPage(pageNum);
    }
}

//
// Test PDFPromise allows return value mutation
//
var promise: PDFPromise<string> = PDFJS.getDocument('helloworld.pdf').then(pdf => {
	return "arbitrary string";
});