var request = require('request');
var jwt = require('jsonwebtoken')
function getAccessToken(req) {
	//https://gist.github.com/demelziraptor/9039435 Python
	//http://www.getcodesamples.com/src/A39B1460/F692912D  PHP    
	req.session.sp_info = req.query;
	req.session.sp_oauth = req.body;

	var client_ID = "{{clientID}}"

	var appSecret = '{{appSecret}}';

	var decoded = jwt.decode(req.session.sp_oauth.SPAppToken, appSecret)

	decoded.appctx = JSON.parse(decoded.appctx);

	var appctx = decoded.appctx;

	var options = {
		headers: {
			"Content-Type": "application/x-www-form-urlencoded"
		},
		form: {
			"grant_type": "refresh_token",
			"client_id": client_ID + '@' + decoded['appctxsender'].split('@')[1],
			"client_secret": appSecret,
			"refresh_token": decoded.refreshtoken,
			"resource": decoded['appctxsender'].split('@')[0] + '/' + "<domain>.sharepoint.com" + '@' + decoded['appctxsender'].split('@')[1]
		}
	};

	console.log('\noptions\n', JSON.stringify(options));
	var callback = function (req, res, body) {
		console.log(JSON.stringify(body));
	}

	request.post(appctx.SecurityTokenServiceUri, options, callback)
}