Files
go-cart-actor/message.go
matst80 65a969443a stuff
2024-11-08 21:58:28 +01:00

146 lines
3.0 KiB
Go

package main
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"time"
messages "git.tornberg.me/go-cart-actor/proto"
"google.golang.org/protobuf/proto"
)
type StorableMessage interface {
Write(w io.Writer) error
}
type Message struct {
Type uint16
TimeStamp *int64
Content interface{}
}
type MessageWriter struct {
io.Writer
}
type StorableMessageHeader struct {
Version uint16
Type uint16
TimeStamp int64
DataLength uint64
}
func GetData(fn func(w io.Writer) error) ([]byte, error) {
var buf bytes.Buffer
err := fn(&buf)
if err != nil {
return nil, err
}
b := buf.Bytes()
return b, nil
}
// func (w *MessageWriter) WriteUint64(value uint64) (int, error) {
// bytes := make([]byte, 8)
// binary.LittleEndian.PutUint64(bytes, value)
// return w.Write(bytes)
// }
// func (w *MessageWriter) WriteInt64(value int64) (int, error) {
// return w.WriteUint64(uint64(value))
// }
// func (w *MessageWriter) WriteMessage(m *Message) (int, error) {
// var i, l int
// var err error
// i, err = w.WriteUint64(m.Type)
// l += i
// i, err = w.WriteInt64(*m.TimeStamp)
// l += i
// var messageBytes []byte
// var err error
// if m.Type == AddRequestType {
// messageBytes, err = proto.Marshal(m.Content.(*messages.AddRequest))
// } else if m.Type == AddItemType {
// messageBytes, err = proto.Marshal(m.Content.(*messages.AddItem))
// } else {
// return fmt.Errorf("unknown message type")
// }
// if err != nil {
// return err
// }
// if err := w.WriteUint64(uint64(len(messageBytes))); err != nil {
// return err
// }
// _, err = w.Write(messageBytes)
// return err
// }
func (m Message) Write(w io.Writer) error {
data, err := GetData(func(wr io.Writer) error {
if m.Type == AddRequestType {
messageBytes, err := proto.Marshal(m.Content.(*messages.AddRequest))
if err != nil {
return err
}
wr.Write(messageBytes)
} else if m.Type == AddItemType {
messageBytes, err := proto.Marshal(m.Content.(*messages.AddItem))
if err != nil {
return err
}
wr.Write(messageBytes)
}
return nil
})
if err != nil {
return err
}
ts := time.Now().Unix()
if m.TimeStamp != nil {
ts = *m.TimeStamp
}
err = binary.Write(w, binary.LittleEndian, StorableMessageHeader{
Version: 1,
Type: m.Type,
TimeStamp: ts,
DataLength: uint64(len(data)),
})
w.Write(data)
return err
}
func MessageFromReader(reader io.Reader, m *Message) error {
header := StorableMessageHeader{}
err := binary.Read(reader, binary.LittleEndian, &header)
if err != nil {
return err
}
messageBytes := make([]byte, header.DataLength)
_, err = reader.Read(messageBytes)
if err != nil {
return err
}
switch header.Type {
case AddRequestType:
msg := &messages.AddRequest{}
err = proto.Unmarshal(messageBytes, msg)
m.Content = msg
case AddItemType:
msg := &messages.AddItem{}
err = proto.Unmarshal(messageBytes, msg)
m.Content = msg
default:
return fmt.Errorf("unknown message type")
}
if err != nil {
return err
}
return nil
}