package main

import (
	"log"
	"os"
    "context"
    "syscall"
	"github.com/hanwen/go-fuse/v2/fs"
	"github.com/hanwen/go-fuse/v2/fuse"
)

type ITNode struct {
	fs.Inode
	kind int
}

var _ = (fs.NodeReaddirer)((*ITNode)(nil))

// Readdir is part of the NodeReaddirer interface
func (n *ITNode) Readdir(ctx context.Context) (fs.DirStream, syscall.Errno) {
	if n.kind == 0 {
		// root folder
		r := make([]fuse.DirEntry, 2)
		r[0] = fuse.DirEntry{
			Name: "device",
			Ino:  0,
			Mode: fuse.S_IFDIR,
		}
		r[1] = fuse.DirEntry{
			Name: "fs",
			Ino:  1,
			Mode: fuse.S_IFDIR,
		}
		return fs.NewListDirStream(r), 0
	}
	r := make([]fuse.DirEntry, 0)
	return fs.NewListDirStream(r), 0
}

var _ = (fs.NodeLookuper)((*ITNode)(nil))
func (n *ITNode) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*fs.Inode, syscall.Errno) {
	if n.kind == 0 {
		if name == "device" {
			stable := fs.StableAttr{
				Mode: fuse.S_IFDIR,
				Ino: uint64(0),
			}
			operations := &ITNode{kind: 1}
			child := n.NewInode(ctx, operations, stable)
			return child, 0
		} else if name == "fs" {
			stable := fs.StableAttr{
				Mode: fuse.S_IFDIR,
				Ino: uint64(1),
			}
			operations := &ITNode{kind: 2}
			child := n.NewInode(ctx, operations, stable)
			return child, 0
		}
	}
	return nil, syscall.ENOENT
}


func main() {
	// This is where we'll mount the FS
	mntDir := "/tmp/x"
	os.Mkdir(mntDir, 0755)
	root := &ITNode{kind: 0}
	server, err := fs.Mount(mntDir, root, &fs.Options{
		MountOptions: fuse.MountOptions{
			// Set to true to see how the file system works.
			Debug: false,
		},
	})
	if err != nil {
		log.Panic(err)
	}

	log.Printf("Mounted on %s", mntDir)
	log.Printf("Unmount by calling 'fusermount -u %s'", mntDir)

	// Wait until unmount before exiting
	server.Wait()
}