BREAKING CHANGE(core): replace the TypeScript database engine with a Rust-backed embedded server and bridge

rust/crates/rustdb-wire/src/codec.rs

@@ -0,0 +1,49 @@
+use bytes::{Buf, BytesMut};
+use tokio_util::codec::{Decoder, Encoder};
+
+use crate::error::WireError;
+use crate::parser::{parse_message, ParsedCommand};
+
+/// Tokio codec for framing wire protocol messages on a TCP stream.
+///
+/// The wire protocol is naturally length-prefixed:
+/// the first 4 bytes of each message contain the total message length.
+pub struct WireCodec;
+
+impl Decoder for WireCodec {
+    type Item = ParsedCommand;
+    type Error = WireError;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        if src.len() < 4 {
+            return Ok(None);
+        }
+
+        // Peek at message length
+        let msg_len = i32::from_le_bytes([src[0], src[1], src[2], src[3]]) as usize;
+
+        if src.len() < msg_len {
+            // Reserve space for the rest of the message
+            src.reserve(msg_len - src.len());
+            return Ok(None);
+        }
+
+        match parse_message(src)? {
+            Some((cmd, bytes_consumed)) => {
+                src.advance(bytes_consumed);
+                Ok(Some(cmd))
+            }
+            None => Ok(None),
+        }
+    }
+}
+
+/// Encoder for raw byte responses (already serialized by the command handlers).
+impl Encoder<Vec<u8>> for WireCodec {
+    type Error = WireError;
+
+    fn encode(&mut self, item: Vec<u8>, dst: &mut BytesMut) -> Result<(), Self::Error> {
+        dst.extend_from_slice(&item);
+        Ok(())
+    }
+}