Fix save-loop and add clean-up

Now the `save-loop` will clean up all sessions except the last.
It is also possible to call the clean up by `clean-up` command.

main.go

@@ -24,9 +24,6 @@ func main() {
 		t.Must(s.Save())
 
 	case "save-loop":
-		s, err := session.New()
-		t.Must(err)
-
 		durationInterval := time.Duration(60)
 		if len(os.Args) >= 3 {
 			interval, err := strconv.Atoi(os.Args[2])
@@ -35,14 +32,20 @@ func main() {
 		}
 
 		for {
+			s, err := session.New()
+			t.Must(err)
 			time.Sleep(durationInterval * time.Second)
 			t.Must(s.Save())
+			session.CleanUp()
 		}
 
 	case "restore":
 		s, err := session.LoadNewest()
 		t.Must(err)
 
 		t.Must(s.Restore())
+
+	case "clean-up":
+		t.Must(session.CleanUp())
 	}
 }

session/session.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"io/ioutil"
 	"log"
+	"os"
 	"path"
 	"path/filepath"
 	"sort"
@@ -107,3 +108,34 @@ func (s *Session) Restore() (err error) {
 
 	return
 }
+
+// CleanUp delete all session files except the last
+func CleanUp() (err error) {
+	files, err := ioutil.ReadDir(sessionsPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if len(files) == 0 {
+		return
+	}
+
+	sort.Slice(files, func(i, j int) bool {
+		iUnix := timestampFromFilename(files[i].Name())
+		jUnix := timestampFromFilename(files[j].Name())
+		return iUnix > jUnix
+	})
+
+	for i, file := range files {
+		if i == 0 {
+			continue
+		}
+
+		err = os.Remove(path.Join(sessionsPath, file.Name()))
+		if err != nil {
+			return
+		}
+	}
+
+	return
+}