package adal

// Copyright 2017 Microsoft Corporation

//

//  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.

import (

	"encoding/json"

	"fmt"

	"io/ioutil"

	"os"

	"path/filepath"

)

// LoadToken restores a Token object from a file located at 'path'.

func LoadToken(path string) (*Token, error) {

	file, err := os.Open(path)

	if err != nil {

		return nil, fmt.Errorf("failed to open file (%s) while loading token: %v", path, err)

	}

	defer file.Close()

	var token Token

	dec := json.NewDecoder(file)

	if err = dec.Decode(&token); err != nil {

		return nil, fmt.Errorf("failed to decode contents of file (%s) into Token representation: %v", path, err)

	}

	return &token, nil

}

// SaveToken persists an oauth token at the given location on disk.

// It moves the new file into place so it can safely be used to replace an existing file

// that maybe accessed by multiple processes.

func SaveToken(path string, mode os.FileMode, token Token) error {

	dir := filepath.Dir(path)

	err := os.MkdirAll(dir, os.ModePerm)

	if err != nil {

		return fmt.Errorf("failed to create directory (%s) to store token in: %v", dir, err)

	}

	newFile, err := ioutil.TempFile(dir, "token")

	if err != nil {

		return fmt.Errorf("failed to create the temp file to write the token: %v", err)

	}

	tempPath := newFile.Name()

	if err := json.NewEncoder(newFile).Encode(token); err != nil {

		return fmt.Errorf("failed to encode token to file (%s) while saving token: %v", tempPath, err)

	}

	if err := newFile.Close(); err != nil {

		return fmt.Errorf("failed to close temp file %s: %v", tempPath, err)

	}

	// Atomic replace to avoid multi-writer file corruptions

	if err := os.Rename(tempPath, path); err != nil {

		return fmt.Errorf("failed to move temporary token to desired output location. src=%s dst=%s: %v", tempPath, path, err)

	}

	if err := os.Chmod(path, mode); err != nil {

		return fmt.Errorf("failed to chmod the token file %s: %v", path, err)

	}

	return nil

}