Basic login functionality

owe.js

@@ -55,6 +55,29 @@ async function loadConfig() {
 	});
 }
 
+function getUsernameFromCookie() {
+    // Split the document.cookie string into individual cookie key-value pairs
+    var cookies = document.cookie.split(';').map(cookie => cookie.trim());
+
+    // Loop through the cookies to find the 'owe_user' cookie
+    for (var i = 0; i < cookies.length; i++) {
+        var cookie = cookies[i];
+        if (cookie.startsWith('owe_user=')) {
+            // Extract the username from the 'owe_user' cookie
+            return decodeURIComponent(cookie.substring('owe_user='.length));
+        }
+    }
+
+    // Return null if the 'owe_user' cookie is not set
+    return null;
+}
+
+function deleteUsernameCookie() {
+    // Set the 'owe_user' cookie to expire by setting its expiration date to a time in the past
+    document.cookie = 'owe_user=; expires=Thu, 01 Jan 1970 00:00:00 UTC; path=.;';
+}
+
+
 function onReloadClicked() {
 	loadSentences();
 	document.querySelector("#but-reload").style.visibility = "hidden";
@@ -228,16 +251,34 @@ async function getLastTimeFromArchive(archiveFileUrl) {
     }
 }
 
+function logoutUser() {
+    deleteUsernameCookie();
+    initializeLoginArea(); // Reload everything in the login area 
+}
 
 async function initializeLoginArea() {
     var loginArea = document.getElementById('login_area');
 
+    var sendButton = document.getElementById('sendbut');
+    sendButton.style.display = "unset"
+    var wordInput = document.getElementById('wordinput');
+    wordInput.disabled = false;
+
     // Use async/await to wait for the result of getNextPlayer
     try {
+        var loggedInPlayer = getUsernameFromCookie();
         var nextPlayer = await getNextPlayer();
         var relative_time = await getTimeSinceLast();
     	// Clear the login area
     	loginArea.innerHTML = "";
+        if (loggedInPlayer != null) {
+            loginArea.innerHTML += "Du bist angemeldet als " + loggedInPlayer + "."
+            loginArea.innerHTML += " <button onclick='logoutUser()'>abmelden</button><br>\n";
+            if (loggedInPlayer != nextPlayer) {
+                sendButton.style.display = "none";
+                wordInput.disabled = true;
+            }
+        }
         loginArea.innerHTML += nextPlayer + " ist dran!<br>\n";
 
         var days = Math.floor(relative_time / (3600 * 24));