add exchanges to internal model

haesli_messaging/src/routing.rs

@@ -0,0 +1,30 @@
+use haesli_core::{
+    exchange::{Exchange, ExchangeType},
+    queue::Queue,
+};
+
+pub fn bind(exchange: &mut Exchange, routing_key: String, queue: Queue) {
+    match &mut exchange.kind {
+        ExchangeType::Direct { bindings } => {
+            bindings.insert(routing_key, queue);
+        }
+        ExchangeType::Fanout { bindings } => bindings.push(queue),
+        ExchangeType::Topic { bindings } => bindings.push((routing_key, queue)),
+        ExchangeType::Headers => {} // unsupported
+        ExchangeType::System => {}  // unsupported
+    }
+}
+
+/// Route a message to a queue. Returns the queue to send it to, or `None` if it can't be matched
+pub fn route_message(exchange: &Exchange, routing_key: &str) -> Option<Queue> {
+    match &exchange.kind {
+        ExchangeType::Direct { bindings } => {
+            // 3.1.3.1 - routing-key = routing-key
+            bindings.get(routing_key).cloned()
+        }
+        ExchangeType::Fanout { .. } => None,
+        ExchangeType::Topic { .. } => None,
+        ExchangeType::Headers => None, // unsupported
+        ExchangeType::System => None,  // unsupported
+    }
+}