package fs

import (
	"io/ioutil"
	"os"
	"path/filepath"
)

// FileSystem defines the methods of an abstract filesystem.
type FileSystem interface {

	// ReadDir reads the directory named by dirname and returns a
	// list of directory entries.
	ReadDir(dirname string) ([]os.FileInfo, error)

	// Lstat returns a FileInfo describing the named file. If the file is a
	// symbolic link, the returned FileInfo describes the symbolic link. Lstat
	// makes no attempt to follow the link.
	Lstat(name string) (os.FileInfo, error)

	// Join joins any number of path elements into a single path, adding a
	// separator if necessary. The result is Cleaned; in particular, all
	// empty strings are ignored.
	//
	// The separator is FileSystem specific.
	Join(elem ...string) string
}

// fs represents a FileSystem provided by the os package.
type fs struct{}

func (f *fs) ReadDir(dirname string) ([]os.FileInfo, error) { return ioutil.ReadDir(dirname) }

func (f *fs) Lstat(name string) (os.FileInfo, error) { return os.Lstat(name) }

func (f *fs) Join(elem ...string) string { return filepath.Join(elem...) }