// Copyright 2016 the Go-FUSE Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pathfs

import (
	"syscall"
	"time"

	"github.com/hanwen/go-fuse/fuse"
)

const _UTIME_NOW = ((1 << 30) - 1)
const _UTIME_OMIT = ((1 << 30) - 2)

// timeToTimeval - Convert time.Time to syscall.Timeval
//
// Note: This does not use syscall.NsecToTimespec because
// that does not work properly for times before 1970,
// see https://github.com/golang/go/issues/12777
func timeToTimeval(t *time.Time) syscall.Timeval {
	var tv syscall.Timeval
	tv.Usec = int32(t.Nanosecond() / 1000)
	tv.Sec = t.Unix()
	return tv
}

// OSX does not have the utimensat syscall neded to implement this properly.
// We do our best to emulate it using futimes.
func (fs *loopbackFileSystem) Utimens(path string, a *time.Time, m *time.Time, context *fuse.Context) fuse.Status {
	tv := make([]syscall.Timeval, 2)
	if a == nil {
		tv[0].Usec = _UTIME_OMIT
	} else {
		tv[0] = timeToTimeval(a)
	}

	if m == nil {
		tv[1].Usec = _UTIME_OMIT
	} else {
		tv[1] = timeToTimeval(m)
	}

	err := syscall.Utimes(fs.GetPath(path), tv)
	return fuse.ToStatus(err)
}