feat: cleanup old backups

cleanup.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"sort"
+)
+
+func cleanupOldBackups() error {
+	files, err := ioutil.ReadDir(config.Folder)
+	if err != nil {
+		return err
+	}
+
+	if len(files) < config.MaxBackups {
+		return nil
+	}
+
+	sort.Slice(files, func(i, j int) bool {
+		return files[i].ModTime().Unix() < files[j].ModTime().Unix()
+	})
+
+	oldest := files[:len(files)-config.MaxBackups]
+
+	for _, file := range oldest {
+		log.Printf("Removing old backup folder %s...\n", file.Name())
+		err = os.RemoveAll(config.Folder + file.Name())
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}