tokio-tutorial-jbarszczewski: Implement actual balance data handling

[learn-rust.git] / tokio-tutorial-jbarszczewski / src / main.rs

diff --git a/tokio-tutorial-jbarszczewski/src/main.rs b/tokio-tutorial-jbarszczewski/src/main.rs
index e1c7800d242f5b87543562288221967a491d5208..f998acc288997a887307ef57b4eb129b85e7b540 100644 (file)
--- a/tokio-tutorial-jbarszczewski/src/main.rs
+++ b/tokio-tutorial-jbarszczewski/src/main.rs
@@ -1,18 +1,52 @@
-use tokio::io::AsyncWriteExt;
-use tokio::net::{TcpListener, TcpStream};
+use std::str;
+use std::sync::{ Arc, Mutex };
+
+use tokio::io::{ AsyncReadExt, AsyncWriteExt };
+use tokio::net::{ TcpListener, TcpStream };
 
 #[tokio::main]
 async fn main() {
+    let balance = Arc::new(Mutex::new(0.0f64));
     let listener = TcpListener::bind("127.0.0.1:8181").await.unwrap();
 
     loop {
         let (stream, _) = listener.accept().await.unwrap();
-        tokio::spawn(async move { handle_connection(stream).await });
+        let balance_ref = balance.clone();
+        tokio::spawn(async move { handle_connection(stream, balance_ref).await });
     }
 }
 
-async fn handle_connection(mut stream: TcpStream) {
-    let contents = "{\"balance\": 0.00}";
+async fn handle_connection(mut stream: TcpStream, balance: Arc<Mutex<f64>>) {
+    // Read the first 16 characters from the incoming stream
+    let mut buffer = [0; 16];
+    assert!(stream.read(&mut buffer).await.unwrap() >= 16);
+    // First 4 characters are used to detect HTTP method
+    let method_type = match str::from_utf8(&buffer[0..4]) {
+        Ok(v) => v,
+        Err(e) => panic!("Invalid UTF-8 sequence: {}", e),
+    };
+
+    let contents = match method_type {
+        "GET " => {
+            format!("{{\"balance\": {}}}", balance.lock().unwrap())
+        }
+        "POST" => {
+            // Take characters after 'POST /' until whitespace is detected.
+            let input: String = buffer[6..16]
+                .iter()
+                .take_while(|x| **x != 32u8)
+                .map(|x| *x as char)
+                .collect();
+            let balance_update = input.parse::<f64>().unwrap();
+            println!("got POST request to update by {}", balance_update);
+            let mut locked_balance = balance.lock().unwrap();
+            *locked_balance += balance_update;
+            format!("{{\"balance\": {}}}", locked_balance)
+        }
+        _ => {
+            panic!("Invalid HTTP method!")
+        }
+    };
 
     let response = format!(
         "HTTP/1.1 200 OK\r\nContent-Type: application/json\r\nContent-Length: {}\r\n\r\n{}",