package storage

import (
	"io/ioutil"
	"path"
)

// fileStore stores a cwtchPeer in an encrypted file
type fileStore struct {
	directory string
	filename  string
	password  string
}

// FileStore is a primitive around storing encrypted files
type FileStore interface {
	Save([]byte) error
	Load() ([]byte, error)
}

// NewFileStore instantiates a fileStore given a filename and a password
func NewFileStore(directory string, filename string, password string) FileStore {
	filestore := new(fileStore)
	filestore.password = password
	filestore.filename = filename
	filestore.directory = directory
	return filestore
}

// save serializes a cwtchPeer to a file
func (fps *fileStore) Save(data []byte) error {
	key, salt, _ := createKey(fps.password)
	encryptedbytes, err := encryptFileData(data, key)
	if err != nil {
		return err
	}

	// the salt for the derived key is appended to the front of  the file
	encryptedbytes = append(salt[:], encryptedbytes...)
	err = ioutil.WriteFile(path.Join(fps.directory, fps.filename), encryptedbytes, 0600)
	return err

}

func (fps *fileStore) Load() ([]byte, error) {
	return readEncryptedFile(fps.directory, fps.filename, fps.password)
}