start implementing ovserver

src/gateway.rs

@@ -1,4 +1,41 @@
 #[derive(Debug)]
-pub struct Gateway {
-    url: String,
+pub struct Gateway {}
+
+pub trait Observer {
+    fn update(&self, data: &str);
+}
+
+pub struct GatewayEvent<'a> {
+    observers: Vec<&'a dyn Observer>,
+    test_content: String,
+}
+
+impl<'a> GatewayEvent<'a> {
+    pub fn new(test_content: String) -> Self {
+        Self {
+            observers: Vec::new(),
+            test_content,
+        }
+    }
+
+    pub fn subscribe(&mut self, observable: &'a dyn Observer) {
+        self.observers.push(observable)
+    }
+
+    pub fn unsubscribe(&mut self, observable: &'a dyn Observer) {
+        if let Some(index) = self.observers.iter().position(|&o| o == observable) {
+            self.observers.remove(index);
+        }
+    }
+
+    pub fn update_data(&mut self, test_content: String) {
+        self.test_content = test_content;
+        self.notify();
+    }
+
+    pub fn notify(&self) {
+        for observer in &self.observers {
+            observer.update(&self.test_content);
+        }
+    }
 }