echo works, only external crate is serde

Cargo.lock

@@ -198,9 +198,8 @@ dependencies = [
 name = "gg-echo"
 version = "0.0.1"
 dependencies = [
- "async-trait",
- "maelstrom-node",
- "tokio",
+ "maelstrom-protocol",
+ "serde_json",
 ]
 
 [[package]]

gg-echo/Cargo.toml

@@ -5,6 +5,5 @@ version.workspace = true
 authors.workspace = true
 
 [dependencies]
-async-trait.workspace = true
-maelstrom-node.workspace = true
-tokio.workspace = true
+serde_json.workspace = true
+maelstrom-protocol = { path = "../maelstrom-protocol" }

gg-echo/src/main.rs

@@ -1,29 +1,56 @@
-use async_trait::async_trait;
-use maelstrom::protocol::Message;
-use maelstrom::{done, Node, Result, Runtime};
-use std::sync::Arc;
+use maelstrom_protocol as proto;
+use proto::{Body, Message};
+use std::io::{BufRead, Write};
 
-#[tokio::main]
-async fn main() {
-    let handler = Arc::new(Handler::default());
-    let _ = Runtime::new()
-        .with_handler(handler)
-        .run()
-        .await
-        .unwrap_or_default();
-}
+fn main() {
+    let mut out = std::io::stdout().lock();
+    let input = std::io::stdin().lock();
 
-#[derive(Clone, Default)]
-struct Handler {}
+    let mut mid = 1;
 
-#[async_trait]
-impl Node for Handler {
-    async fn process(&self, runtime: Runtime, req: Message) -> Result<()> {
-        if req.get_type() == "echo" {
-            let echo = req.body.clone().with_type("echo_ok");
-            return runtime.reply(req, echo).await;
+    let mut node_id: String = "".to_string();
+
+    for line in input.lines() {
+        match line {
+            Ok(line) => {
+                if let Ok(msg) = serde_json::from_str::<proto::Message>(&line) {
+                    let typ = &msg.body.typ;
+                    match typ.as_str() {
+                        "init" => {
+                            let body = proto::init_ok(mid, msg.body.msg_id);
+                            mid += 1;
+                            let resp = message(&msg.src, &msg.dest, body);
+                            node_id = msg.dest;
+                            let resp = serde_json::to_string(&resp).unwrap();
+                            out.write_all(resp.as_bytes()).unwrap();
+                            out.write_all("\n".as_bytes()).unwrap();
+                            let _ = &mut out.flush().unwrap();
+                        }
+                        "echo" => {
+                            let body = Body::from_type("echo_ok")
+                                .with_msg_id(mid)
+                                .with_in_reply_to(msg.body.msg_id)
+                                .with_payload(msg.body.payload);
+                            mid += 1;
+                            let resp = message(&msg.src, &node_id, body);
+                            let resp = serde_json::to_string(&resp).unwrap();
+                            out.write_all(resp.as_bytes()).unwrap();
+                            out.write_all("\n".as_bytes()).unwrap();
+                            let _ = &mut out.flush().unwrap();
+                        }
+                        _ => {}
+                    }
+                }
+            }
+            _ => {}
         }
-
-        done(runtime, req)
+    }
+}
+
+fn message(dest: &str, src: &str, body: Body) -> Message {
+    Message {
+        dest: dest.to_owned(),
+        src: src.to_owned(),
+        body,
     }
 }

maelstrom-protocol/src/lib.rs

@@ -6,12 +6,12 @@ pub type Payload = Map<String, Value>;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct Message {
-    src: String,
-    dest: String,
-    body: Body,
+    pub src: String,
+    pub dest: String,
+    pub body: Body,
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct Body {
     #[serde(rename = "type")]
     pub typ: String,
@@ -23,6 +23,39 @@ pub struct Body {
     pub payload: Payload,
 }
 
+impl Body {
+    pub fn from_type(typ: &str) -> Self {
+        Body {
+            typ: typ.to_string(),
+            ..Default::default()
+        }
+    }
+
+    pub fn with_msg_id(self, msg_id: u64) -> Self {
+        let mut b = self;
+        b.msg_id = msg_id;
+        b
+    }
+
+    pub fn with_in_reply_to(self, in_reply_to: u64) -> Self {
+        let mut b = self;
+        b.in_reply_to = in_reply_to;
+        b
+    }
+
+    pub fn with_payload(self, payload: Payload) -> Self {
+        let mut b = self;
+        b.payload = payload;
+        b
+    }
+}
+
+pub fn init_ok(msg_id: u64, in_reply_to: u64) -> Body {
+    Body::from_type("init_ok")
+        .with_msg_id(msg_id)
+        .with_in_reply_to(in_reply_to)
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(untagged)]
 pub enum ErrorCode {
@@ -51,15 +84,6 @@ pub enum IndefiniteError {
     Crash = 13,
 }
 
-pub fn init_ok(msg_id: u64, in_reply_to: u64) -> Body {
-    Body {
-        typ: "init_ok".to_string(),
-        msg_id,
-        in_reply_to,
-        payload: Payload::new(),
-    }
-}
-
 pub fn error(msg_id: u64, in_reply_to: u64, code: ErrorCode, text: Option<&str>) -> Body {
     Body {
         typ: "error".to_string(),