package main

import (
	"fmt"
	"path"
	"sync"

	p9 "github.com/Harvey-OS/ninep/protocol"

	"git.samanthony.xyz/buth/back/auth"
)

const (
	_ uint64 = iota
	rootQidPath
	usersQidPath
	sessionsQidPath
)

type File interface {
	Qid() (p9.QID, error)
	// TODO
}

type Dir interface {
	File
	// TODO: walk, create
}

// Authfs is the root p9.NineServer.
type Authfs struct {
	*RootDir
	*UsersDir
	*SessionsDir

	mu    sync.Mutex // guards below
	files map[p9.FID]File
}

func NewAuthfs(rootPath string) (*Authfs, error) {
	root := NewRootDir()
	users, err := NewUsersDir(rootPath, root.Version)
	if err != nil {
		return nil, err
	}
	return &Authfs{
		root,
		users,
		NewSessionsDir(root.Version),
		sync.Mutex{},
		make(map[p9.FID]File),
	}, nil
}

func (fs *Authfs) Close() {
	fs.RootDir.Close()
	fs.UsersDir.Close()
	fs.SessionsDir.Close()
}

func (fs *Authfs) Rattach(fid, afid p9.FID, uname, aname string) (p9.QID, error) {
	if afid != p9.NOFID {
		return p9.QID{}, fmt.Errorf("authfs: no authentication required")
	}

	var (
		f   File
		err error
		ok  bool
	)

	aname = path.Clean(path.Join("/", aname))
	dir, file := path.Split(aname)
	switch dir {
	case "/":
		switch file {
		case "":
			f = fs.RootDir
		case "users":
			f = fs.UsersDir
		case "sessions":
			f = fs.SessionsDir
		default:
			return p9.QID{}, ErrFileNotExist
		}

	case "/users/":
		f, err = fs.UsersDir.Walk(file)
		if err != nil {
			return p9.QID{}, err
		}

	case "/sessions/":
		sessid, err := auth.ParseSessId(file)
		if err != nil {
			return p9.QID{}, err
		}
		f, ok = fs.SessionsDir.Get(sessid)
		if !ok {
			return p9.QID{}, ErrFileNotExist
		}

	default:
		return p9.QID{}, ErrFileNotExist
	}
	if f == nil {
		panic("unreachable")
	}

	qid, err := f.Qid()
	if err != nil {
		return p9.QID{}, err
	}
	if err := fs.attach(fid, f); err != nil {
		return p9.QID{}, err
	}
	return qid, nil
}

func (fs *Authfs) attach(fid p9.FID, f File) error {
	fs.mu.Lock()
	defer fs.mu.Unlock()

	if _, exists := fs.files[fid]; exists {
		return ErrFidExist
	}

	fs.files[fid] = f
	return nil
}