FirstTimeAuthXero

//(Only First time)THIS IS FIRST LEVEL AUTHENTICATION WHERE YOU WILL RECEIVE 'access_token' & 'refresh_token'..
	@future(callout = true)
	public static void authenticateUsingAuthCode() {
		XeroSettings xss = new XeroSettings();
		String authCode = xss.authCode;
		System.debug('MARK:==> authenticateUsingAuthCode() -- authenticating... using =' + authCode);
		//String encodeString = XeroConfig.Client_Id + ':'+ XeroConfig.Client_Secret;
		String encodeString = xss.clientId + ':' + xss.clientSecret;
		System.debug('MARK:==> authenticateUsingAuthCode() beforeEncoding =' + encodeString);
		String authorizationHeader = 'Basic ' + EncodingUtil.base64Encode(Blob.valueOf(encodeString));
		System.debug('MARK:==> authenticateUsingAuthCode() afterEncoding =' + authorizationHeader);
		String redirectUrl = 'https://www.zulu8.com';
		String body = 'grant_type=authorization_code&code=' + authCode + '&redirect_uri=' + redirectUrl;

		//--------------------
		HttpRequest request1 = new HttpRequest();
		request1.setEndpoint('https://identity.xero.com/connect/token');
		request1.setMethod('POST');
		request1.setHeader('Authorization', authorizationHeader);
		request1.setHeader('Content-Type', 'application/x-www-form-urlencoded');
		request1.setBody(body);
		request1.setHeader('Content-Length', String.valueOf(body.length()));
		//---------------------------
		Http h1 = new Http();
		HttpResponse res1 = h1.send(request1);
		System.debug('MARK:--> authenticateUsingAuthCode() =' + res1.getBody());
		AccessToken accessTokenRes = AccessToken.parse(res1.getBody());
		if (accessTokenRes != null && accessTokenRes.access_token.length() > 0) {
			System.debug('MARK:==> authenticateUsingAuthCode() -- finished....Access_Token =' + accessTokenRes.access_token + ' Refresh_Token =' + accessTokenRes.refresh_token);
			String token = accessTokenRes.access_token;
			String method = 'GET';
			String endpoint = 'https://api.xero.com/connections';
			HTTPRequest req = new HTTPRequest();
			req.setHeader('Content-Type', 'application/json'); //setHeader('Content-Type','application/x-www-form-urlencoded');
			req.setHeader('Authorization', 'Bearer ' + token);
			req.setMethod(method);
			req.setEndpoint(endpoint);
			HTTP h = new HTTP();
			HTTPResponse res = h.send(req);
			System.debug('MARK:==> getTenant() response =' + res.getBody());
			Tenant tnnt = Tenant.parse(res.getBody());
			if (tnnt != null) {
				xss.addTenant(tnnt);
				xss.accessToken = accessTokenRes.access_token;
				xss.refreshToken = accessTokenRes.refresh_token;
				xss.expirySeconds = accessTokenRes.expires_in;
				xss.authCode = authCode;
				xss.save();
			}
			return;
		}
		System.debug('MARK:==> authenticateUsingAuthCode() -- not finished.... Response =' + res1.getBody());
		return;
	}