From e8d917fcef21d606a8b48a2f8cc397daac3e4017 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20Krzy=C5=BCanowski?= <krzmaciek@gmail.com>
Date: Sat, 28 Dec 2024 03:31:45 +0100
Subject: [PATCH] Finish frameconn

---
 frameconn.go | 67 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 58 insertions(+), 9 deletions(-)

diff --git a/frameconn.go b/frameconn.go
index 0c77807..ccc8f6d 100644
--- a/frameconn.go
+++ b/frameconn.go
@@ -1,6 +1,9 @@
 package main
 
-import "io"
+import (
+	"encoding/binary"
+	"io"
+)
 
 type Typed interface {
 	Type() uint32
@@ -16,26 +19,72 @@ type Frame interface {
 }
 
 type frame struct {
-	TypeID     uint32
-	ValueBytes []byte
+	typeID     uint32
+	valueBytes []byte
 }
 
 func (f frame) Type() uint32 {
-	return f.TypeID
+	return f.typeID
 }
 
 func (f frame) Value() []byte {
-	return f.ValueBytes
+	return f.valueBytes
 }
 
+// FrameReadWriter is a struct encapsulating io.ReadWriter, which provides additional methods for reading and
+// writing frames -- messages which have their own type and value byte buffer.
+// Data sent or received using this socket is expected to be encoded in LTV format, which means:
+// L - 4 bytes of frame length, big endian encoded
+// T - 4 bytes of frame type, big endian encoded
+// V - L bytes of frame data bytes
 type FrameReadWriter struct {
-	rw io.ReadWriter
+	io.ReadWriter
 }
 
-func (FrameReadWriter) ReadFrame() (Frame, error) {
-	return nil, nil
+func (frw FrameReadWriter) ReadFrame() (Frame, error) {
+	lengthBytes := make([]byte, 4)
+	_, err := io.ReadFull(frw, lengthBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	frameLength := binary.BigEndian.Uint32(lengthBytes)
+
+	typeBytes := make([]byte, 4)
+	_, err = io.ReadFull(frw, typeBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	frameType := binary.LittleEndian.Uint32(typeBytes)
+	frameBytes := make([]byte, frameLength)
+	_, err = io.ReadFull(frw, frameBytes)
+	if err != nil {
+		return nil, err
+	}
+
+	result := frame{typeID: frameType, valueBytes: frameBytes}
+
+	return result, nil
 }
 
-func (FrameReadWriter) WriteFrame(f Frame) error {
+func (frw FrameReadWriter) WriteFrame(f Frame) error {
+	frameLength := len(f.Value())
+	lengthBytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(lengthBytes, uint32(frameLength))
+
+	typeBytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(typeBytes, f.Type())
+
+	result := make([]byte, 0)
+	result = append(result, lengthBytes...)
+	result = append(result, typeBytes...)
+	result = append(result, f.Value()...)
+
+	_, err := frw.Write(result)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }