sendfile simple small files usermessage implementation

message.go

@@ -1,5 +1,42 @@
 package meowlib
 
-func (*UserMessage) addFile(filename string) {
+import (
+	"errors"
+	"os"
 
+	"github.com/google/uuid"
+)
+
+func (msg *UserMessage) AddFile(filename string, maxMessageSize int64) error {
+	fi, err := os.Stat(filename)
+	if err != nil {
+		return err
+	}
+	if fi.Size() > maxMessageSize {
+		return errors.New("Cannot add file, file bigger than messge size")
+	}
+	var totalsize int64
+	totalsize = 0
+	for _, f := range msg.Files {
+		totalsize += int64(f.Size)
+	}
+	totalsize += fi.Size()
+	if totalsize > maxMessageSize {
+		return errors.New("Cannot add file, too many files, max message size exceeded")
+	}
+	data, err := os.ReadFile(filename)
+	if err != nil {
+		return err
+	}
+
+	var file File
+	file.Filename = filename
+	file.Size = uint64(fi.Size())
+	file.Data = data
+	msg.Files = append(msg.Files, &file)
+
+	msg.Status = &UserMessage_ConversationStatus{}
+	msg.Status.LocalUuid = uuid.New().String()
+
+	return nil
 }