1 files changed, 98 insertions, 0 deletions
diff --git a/src/proto/codec.rs b/src/proto/codec.rs
new file mode 100644
index 0000000..d8f9b10
--- /dev/null
+++ b/src/proto/codec.rs
@@ -0,0 +1,98 @@
+use bytes::{BufMut, BytesMut};
+use tokio_util::codec::{Decoder, Encoder};
+
+use crate::proto::error::CodecError;
+use crate::proto::message::IrcMessage;
+use crate::proto::parser::parse;
+use crate::proto::serializer::serialize;
+
+const MAX_LINE_LENGTH: usize = 512;
+
+pub struct IrcCodec {
+    max_line_length: usize,
+}
+
+impl IrcCodec {
+    pub fn new() -> Self {
+        Self {
+            max_line_length: MAX_LINE_LENGTH,
+        }
+    }
+
+    pub fn with_max_length(max_line_length: usize) -> Self {
+        Self { max_line_length }
+    }
+}
+
+impl Default for IrcCodec {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Decoder for IrcCodec {
+    type Item = IrcMessage;
+    type Error = CodecError;
+
+    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+        loop {
+            let newline_pos = src.iter().position(|&b| b == b'\n');
+
+            match newline_pos {
+                None => {
+                    if src.len() > self.max_line_length {
+                        return Err(CodecError::Parse(
+                            crate::proto::error::ParseError::MessageTooLong,
+                        ));
+                    }
+                    return Ok(None);
+                }
+                Some(pos) => {
+                    let line_bytes = src.split_to(pos + 1);
+
+                    let line = &line_bytes[..line_bytes.len() - 1]; // strip \n
+                    let line = if line.last() == Some(&b'\r') {
+                        &line[..line.len() - 1] // strip \r
+                    } else {
+                        line
+                    };
+
+                    // Skip empty lines silently
+                    if line.is_empty() {
+                        continue;
+                    }
+
+                    let line_str = std::str::from_utf8(line).map_err(|_| {
+                        CodecError::Io(std::io::Error::new(
+                            std::io::ErrorKind::InvalidData,
+                            "IRC message is not valid UTF-8",
+                        ))
+                    })?;
+
+                    let msg = parse(line_str)?;
+                    return Ok(Some(msg));
+                }
+            }
+        }
+    }
+}
+
+impl Encoder<IrcMessage> for IrcCodec {
+    type Error = CodecError;
+
+    fn encode(&mut self, msg: IrcMessage, dst: &mut BytesMut) -> Result<(), Self::Error> {
+        let line = serialize(&msg);
+
+        // +2 for \r\n
+        if line.len() + 2 > self.max_line_length {
+            return Err(CodecError::Parse(
+                crate::proto::error::ParseError::MessageTooLong,
+            ));
+        }
+
+        dst.reserve(line.len() + 2);
+        dst.put_slice(line.as_bytes());
+        dst.put_slice(b"\r\n");
+        Ok(())
+    }
+}