// Copyright © 2018 Steve Francia <spf@spf13.com>.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

package afero

import (

	"errors"

)

// Symlinker is an optional interface in Afero. It is only implemented by the

// filesystems saying so.

// It indicates support for 3 symlink related interfaces that implement the

// behaviors of the os methods:

//    - Lstat

//    - Symlink, and

//    - Readlink

type Symlinker interface {

	Lstater

	Linker

	LinkReader

}

// Linker is an optional interface in Afero. It is only implemented by the

// filesystems saying so.

// It will call Symlink if the filesystem itself is, or it delegates to, the os filesystem,

// or the filesystem otherwise supports Symlink's.

type Linker interface {

	SymlinkIfPossible(oldname, newname string) error

}

// ErrNoSymlink is the error that will be wrapped in an os.LinkError if a file system

// does not support Symlink's either directly or through its delegated filesystem.

// As expressed by support for the Linker interface.

var ErrNoSymlink = errors.New("symlink not supported")

// LinkReader is an optional interface in Afero. It is only implemented by the

// filesystems saying so.

type LinkReader interface {

	ReadlinkIfPossible(name string) (string, error)

}

// ErrNoReadlink is the error that will be wrapped in an os.Path if a file system

// does not support the readlink operation either directly or through its delegated filesystem.

// As expressed by support for the LinkReader interface.

var ErrNoReadlink = errors.New("readlink not supported")