// Copyright 2015 CNI authors
//
// 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 disk

import (
	"github.com/alexflint/go-filemutex"
	"os"
	"path"
)

// FileLock wraps os.File to be used as a lock using flock
type FileLock struct {
	f *filemutex.FileMutex
}

// NewFileLock opens file/dir at path and returns unlocked FileLock object
func NewFileLock(lockPath string) (*FileLock, error) {
	fi, err := os.Stat(lockPath)
	if err != nil {
		return nil, err
	}

	if fi.IsDir() {
		lockPath = path.Join(lockPath, "lock")
	}

	f, err := filemutex.New(lockPath)
	if err != nil {
		return nil, err
	}

	return &FileLock{f}, nil
}

func (l *FileLock) Close() error {
	return l.f.Close()
}

// Lock acquires an exclusive lock
func (l *FileLock) Lock() error {
	return l.f.Lock()
}

// Unlock releases the lock
func (l *FileLock) Unlock() error {
	return l.f.Unlock()
}