Update auth.js

Fixes #7; Adds placeholder url to indicate the proper format for entering. Adds validation for empty string to doAuth. Tries to upgrade the protocol scheme from http to https when http was entered, tries to prefix https before if the url doesn't start with it.

src/auth.js

@@ -32,6 +32,25 @@ module.exports = function Auth({setOauth}) {
 	}, []);
 
 	function doAuth() {
+		if (typeof instance === "undefined" || instance === null) {
+			return;
+		}
+
+		let instanceUri = instance.trim();
+		if (!instanceUri.toLowerCase().startsWith("https://")) {
+			let inputUri = null;
+			try {
+				inputUri = new URL(instanceUri);
+				inputUri.protocol = "https";
+			} catch (e) {
+				inputUri = new URL("https://"+instanceUri);
+			}
+
+			if (inputUri instanceof URL) {
+				instanceUri = inputUri.toString();
+			}
+		}
+		
 		let oauth = oauthLib({
 			instance: instance,
 			client_name: "GoToSocial Admin Panel",
@@ -60,9 +79,9 @@ module.exports = function Auth({setOauth}) {
 			<h1>OAUTH Login:</h1>
 			<form onSubmit={(e) => e.preventDefault()}>
 				<label htmlFor="instance">Instance: </label>
-				<input value={instance} onChange={updateInstance} id="instance"/>
+				<input value={instance} onChange={updateInstance} id="instance" placeholder="https://gts.instance.xyz"/>
 				<button onClick={doAuth}>Authenticate</button>
 			</form>
 		</section>
 	);
-};
+};