1 files changed, 81 insertions, 0 deletions
diff --git a/core/data.go b/core/data.go
index 0bd8200..7ccc4f9 100644
--- a/core/data.go
+++ b/core/data.go
@@ -1,5 +1,12 @@
 package core
 
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"strings"
+)
+
 type Marshaler interface {
 	Marshal() []any
 }
@@ -22,10 +29,84 @@ func (h Handshake) Marshal() []any {
 	return []any{h.Version}
 }
 
+func ReadHandshake(r io.Reader) (Handshake, error) {
+	var d Handshake
+	err := read(r, &d.Version)
+	return d, err
+}
+
 type Test struct {
 	Message string
 }
 
+func ReadTest(r io.Reader) (Test, error) {
+	var d Test
+	err := readString(r, &d.Message)
+	return d, err
+}
+
 func (h Test) Marshal() []any {
 	return []any{append([]byte(h.Message), 0x0)}
 }
+
+func Read(r io.Reader) (any, error) {
+	dType, err := ReadDataType(r)
+	if err != nil {
+		return nil, fmt.Errorf("cannot read data type", err)
+	}
+
+	switch dType {
+	case TypeUnknown:
+		return nil, fmt.Errorf("cannot read data type 0x00 (TypeUnknown)")
+	case TypeHandshake:
+		return ReadHandshake(r)
+	case TypeTest:
+		return ReadTest(r)
+	default:
+		return nil, fmt.Errorf("unsupported type: %v", dType)
+	}
+}
+
+func ReadDataType(r io.Reader) (DataType, error) {
+	var data uint8
+	if err := read(r, &data); err != nil {
+		return TypeUnknown, err
+	}
+
+	dType := DataType(data)
+
+	return dType, nil
+}
+
+func readString(r io.Reader, ptr *string) error {
+	var (
+		sb  strings.Builder
+		buf byte
+	)
+
+	for {
+		if err := read(r, &buf); err != nil {
+			return err
+		}
+
+		if buf == 0x0 {
+			break
+		}
+
+		if err := sb.WriteByte(buf); err != nil {
+			fmt.Errorf("cannot write byte to string buffer: %v", err)
+		}
+	}
+
+	*ptr = sb.String()
+	return nil
+}
+
+func read(r io.Reader, ptr any) error {
+	err := binary.Read(r, binary.BigEndian, ptr)
+	if err != nil {
+		return fmt.Errorf("cannot read: %v", err)
+	}
+
+	return nil
+}