add timestamp endpoint

I LOVE AI!!!!!!!!!!!!!!

main.js

@@ -9,6 +9,7 @@ require('console-stamp')(console);
 class DoorInfo {
   state = null;
   opener = null;
+  lastChange = null;
 }
 
 const web_host = process.env.HTTP_BIND;
@@ -49,6 +50,8 @@ const update_door_state = (door, state) => {
     return;
   }
 
+  const oldState = doors[door].state;
+  
   switch (state) {
     case "ON":
       console.log(`Door ${door} opened!`);
@@ -62,7 +65,12 @@ const update_door_state = (door, state) => {
 
     default:
       console.log(`Unknown message received for door ${door}`);
-      break;
+      return;
+  }
+
+  // Only update lastChange if the state actually changed
+  if (oldState !== doors[door].state) {
+    doors[door].lastChange = new Date().toISOString();
   }
 };
 
@@ -225,6 +233,39 @@ const server = http.createServer((req, res) => {
     return send_file(res, 200, './static/darkmode.js', 'text/javascript');
   }
 
+  if (req.url === '/state/ucc/lastchange') {
+    if (doors['ucc-door'].lastChange === null) {
+      return send_json(res, 500, null);
+    }
+
+    return send_json(res, 200, {
+      lastChange: doors['ucc-door'].lastChange,
+      state: doors['ucc-door'].state
+    });
+  }
+
+  if (req.url === '/state/unisfa/lastchange') {
+    if (doors['unisfa-door'].lastChange === null) {
+      return send_json(res, 500, null);
+    }
+
+    return send_json(res, 200, {
+      lastChange: doors['unisfa-door'].lastChange,
+      state: doors['unisfa-door'].state
+    });
+  }
+
+  if (req.url === '/state/uwaes/lastchange') {
+    if (doors['uwaes-door'].lastChange === null) {
+      return send_json(res, 500, null);
+    }
+
+    return send_json(res, 200, {
+      lastChange: doors['uwaes-door'].lastChange,
+      state: doors['uwaes-door'].state
+    });
+  }
+
   return send_error(res, 404);
 });