//go:build linux

package fsutils

import (
	`os`
	`reflect`
	`unsafe`

	`golang.org/x/sys/unix`
	`r00t2.io/goutils/bitmask`
	`r00t2.io/sysutils/paths`
)

func GetAttrs(path string) (attrs *FsAttrs, err error) {

	var f *os.File
	var evalAttrs FsAttrs
	var attrVal fsAttr
	var attrValBit bitmask.MaskBit
	var reflectVal reflect.Value
	var field reflect.Value
	var myPath string = path

	if err = paths.RealPath(&myPath); err != nil {
		return
	}

	if f, err = os.Open(myPath); err != nil {
		return
	}
	defer f.Close()

	reflectVal = reflect.ValueOf(&evalAttrs).Elem()

	if attrVal, err = getAttrs(f); err != nil {
		return
	}
	attrValBit = bitmask.MaskBit(attrVal)

	for attrNm, attrInt := range AttrNameValueMap {
		field = reflectVal.FieldByName(attrNm)
		field.SetBool(attrValBit.HasFlag(bitmask.MaskBit(attrInt)))
	}

	attrs = new(FsAttrs)
	*attrs = evalAttrs

	return
}

// getAttrs is the unexported low-level syscall to get attributes.
func getAttrs(f *os.File) (attrVal fsAttr, err error) {

	var u uint
	var curFlags int
	// var errNo syscall.Errno

	/*
		if _, _, errNo = unix.Syscall(unix.SYS_IOCTL, f.Fd(), unix.FS_IOC_GETFLAGS, uintptr(unsafe.Pointer(&curFlags))); errNo != 0 {
			err = os.NewSyscallError("ioctl: FS_IOC_GETFLAGS", errNo)
			return
		}
	*/
	if curFlags, err = unix.IoctlGetInt(int(f.Fd()), unix.FS_IOC_GETFLAGS); err != nil {
		return
	}

	u = uint(curFlags)

	attrVal = fsAttr(u)

	return
}

// invertMap returns some handy consts remapping for easier lookups.
func invertMap(origMap map[string]fsAttr) (newMap map[fsAttr]string) {

	if origMap == nil {
		return
	}
	newMap = make(map[fsAttr]string)

	for k, v := range origMap {
		newMap[v] = k
	}

	return
}

// setAttrs is the unexported low-level syscall to set attributes. attrs may be OR'd.
func setAttrs(f *os.File, attrs fsAttr) (err error) {

	var curAttrs fsAttr
	var ab bitmask.MaskBit
	var errNo unix.Errno
	var val uint

	if curAttrs, err = getAttrs(f); err != nil {
		return
	}
	ab = bitmask.MaskBit(curAttrs)

	if ab.HasFlag(bitmask.MaskBit(attrs)) {
		return
	}

	ab.AddFlag(bitmask.MaskBit(attrs))

	val = ab.Value()

	/*
		if err = unix.IoctlSetInt(int(f.Fd()), unix.FS_IOC_SETFLAGS, int(ab.Value())); err != nil {
			return
		}
	*/
	if _, _, errNo = unix.Syscall(unix.SYS_IOCTL, f.Fd(), unix.FS_IOC_SETFLAGS, uintptr(unsafe.Pointer(&val))); errNo != 0 {
		err = os.NewSyscallError("ioctl: SYS_IOCTL", errNo)
		return
	}

	return
}

// unsetAttrs is the unexported low-level syscall to remove attributes. attrs may be OR'd.
func unsetAttrs(f *os.File, attrs fsAttr) (err error) {

	var curAttrs fsAttr
	var ab bitmask.MaskBit

	if curAttrs, err = getAttrs(f); err != nil {
		return
	}
	ab = bitmask.MaskBit(curAttrs)

	if !ab.HasFlag(bitmask.MaskBit(attrs)) {
		return
	}

	ab.ClearFlag(bitmask.MaskBit(attrs))

	/*
		if err = unix.IoctlSetInt(int(f.Fd()), unix.FS_IOC_SETFLAGS, int(ab.Value())); err != nil {
			return
		}
	*/

	return
}