// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later

package btrfsitem

import (
	"encoding/binary"

	"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
)

// A UUIDMap item goes in the UUID_TREE and maps from a UUID to a
// btrfsprim.ObjID.
//
// The Key for this item is a UUID, and the item is a subvolume ID
// that UUID maps to.
//
// Key:
//
//	key.objectid = first half of UUID
//	key.offset   = second half of UUID
type UUIDMap struct { // trivial UUID_SUBVOL=251 UUID_RECEIVED_SUBVOL=252
	ObjID         btrfsprim.ObjID `bin:"off=0, siz=8"`
	binstruct.End `bin:"off=8"`
}

func KeyToUUID(key btrfsprim.Key) btrfsprim.UUID {
	var uuid btrfsprim.UUID
	binary.LittleEndian.PutUint64(uuid[:8], uint64(key.ObjectID))
	binary.LittleEndian.PutUint64(uuid[8:], key.Offset)
	return uuid
}

func UUIDToKey(uuid btrfsprim.UUID) btrfsprim.Key {
	return btrfsprim.Key{
		ObjectID: btrfsprim.ObjID(binary.LittleEndian.Uint64(uuid[:8])),
		ItemType: UUID_SUBVOL_KEY,
		Offset:   binary.LittleEndian.Uint64(uuid[8:]),
	}
}