backups: implement maintenance sub command

.restic/restic-do

@@ -89,8 +89,32 @@ Stopped $backup_stopped
 $(cat ~/.restore-info/tmp/backup-log-${script_started}.txt)
 EOMAIL
 	;;
-	prune)
-		echo "not implemented yet" ;;
+	maintenance)
+		restic forget -r "$repo" -v --prune \
+			--keep-last 2 --keep-daily 7 --keep-weekly 5 --keep-monthly 6 --keep-yearly 3 \
+			> ~/.restore-info/tmp/maint-forget-log-${script_started}.txt
+		forget_exit_code="$?"
+
+		restic -r "$repo" check --read-data-subset=10% \
+			> ~/.restore-info/tmp/maint-check-log-${script_started}.txt
+		check_exit_code="$?"
+
+		maint_done=$(date +%k%M%S)
+
+		cat <<EOMAIL | msmtp --read-envelope-from $BACKUP_EMAIL_TO
+To: $BACKUP_EMAIL_TO
+From: $BACKUP_EMAIL_FROM
+Subject: Backup maintenance report: $script_started
+
+- Finished $maint_done
+- Forgetting exited $forget_exit_code
+- Checking exiting $check_exit_code
+
+$(cat ~/.restore-info/tmp/maint-forget-log-${script_started}.txt)
+
+$(cat ~/.restore-info/tmp/maint-check-log-${script_started}.txt)
+EOMAIL
+		;;
 	exec)
 		shift
 		restic -r "$repo" "$@" ;;