Revert "Unconditionally redirect everyone to the common landing page"

This reverts commit 20ea792.

extra-assets/js/login.js

@@ -1,6 +1,32 @@
+function redirectIfNeeded() {
+    // Only redirect utoronto.2i2c.cloud, lets us keep staging at staging.utoronto.2i2c.cloud
+    if (window.location.hostname === 'utoronto.2i2c.cloud') {
+        // Let's give users an indication that something is happening
+        document.write("Redirecting you to jupyter.utoronto.ca");
+        window.location.hostname = 'jupyter.utoronto.ca';
+    }
+}
+function setInterface(interfaceUrl) {
+    let loginUrl = new URL($('#home').data('authenticator-login-url'), document.location.origin);
+    loginUrl.searchParams.set('next', '/hub/user-redirect/' + interfaceUrl)
+    $('#login-button').attr(
+        'href',
+        loginUrl.toString()
+    );
+}
 $(function() {
-    // The 'unified' home page for all the hubs is at https://datatools.utoronto.ca,
-    // so anyone landing on the home page should just be redirected.
-    document.write("Redirecting you to datatools.utoronto.ca");
-    window.location.replace("https://datatools.utoronto.ca");
+    redirectIfNeeded();
+    // if next query param is presentm just do nothing
+    const nextPresent = new URL(document.location).searchParams.get('next');
+    // /hub/ being next should be treated same as no next present
+    if (!nextPresent || nextPresent === "/hub/") {
+        setInterface($("input[name='interface']:checked").val());
+
+        $("input[name='interface']").change(function() {
+            if (this.checked) {
+                setInterface(this.value)
+            }
+        });
+    }
+
 })