restructure and error logging

src/topic.rs

@@ -0,0 +1,63 @@
+use crate::device::Device;
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum Topic {
+    LWT(Device),
+    Power(Device),
+    State(Device),
+    Sensor(Device),
+    Result(Device),
+    Other(String),
+}
+
+impl From<&str> for Topic {
+    fn from(raw: &str) -> Self {
+        let mut parts = raw.split('/');
+        if let (Some(prefix), Some(topic), Some(hostname), Some(cmd)) =
+            (parts.next(), parts.next(), parts.next(), parts.next())
+        {
+            let device = Device {
+                topic: topic.to_string(),
+                hostname: hostname.to_string(),
+            };
+            match (prefix, cmd) {
+                ("tele", "LWT") => Topic::LWT(device),
+                ("tele", "STATE") => Topic::State(device),
+                ("stat", "POWER") => Topic::Power(device),
+                ("tele", "SENSOR") => Topic::Sensor(device),
+                ("stat", "RESULT") => Topic::Result(device),
+                _ => Topic::Other(raw.to_string()),
+            }
+        } else {
+            Topic::Other(raw.to_string())
+        }
+    }
+}
+
+#[test]
+fn parse_topic() {
+    let device = Device {
+        hostname: "hostname".to_string(),
+        topic: "foo".to_string(),
+    };
+    assert_eq!(
+        Topic::LWT(device.clone()),
+        Topic::from("tele/foo/hostname/LWT")
+    );
+    assert_eq!(
+        Topic::Power(device.clone()),
+        Topic::from("stat/foo/hostname/POWER")
+    );
+    assert_eq!(
+        Topic::State(device.clone()),
+        Topic::from("tele/foo/hostname/STATE")
+    );
+    assert_eq!(
+        Topic::Sensor(device.clone()),
+        Topic::from("tele/foo/hostname/SENSOR")
+    );
+    assert_eq!(
+        Topic::Result(device.clone()),
+        Topic::from("stat/foo/hostname/RESULT")
+    );
+}