// Copyright 2019 Drone.IO Inc. All rights reserved.
// Use of this source code is governed by the Drone Non-Commercial License
// that can be found in the LICENSE file.

package encrypt

import (
	"crypto/aes"
	"errors"
)

// indicates key size is too small.
var errKeySize = errors.New("encryption key must be 32 bytes")

// Encrypter provides database field encryption and decryption.
// Encrypted values are currently limited to strings, which is
// reflected in the interface design.
type Encrypter interface {
	Encrypt(plaintext string) ([]byte, error)
	Decrypt(ciphertext []byte) (string, error)
}

// New provides a new database field encrypter.
func New(key string) (Encrypter, error) {
	if key == "" {
		return &none{}, nil
	}
	if len(key) != 32 {
		return nil, errKeySize
	}
	b := []byte(key)
	block, err := aes.NewCipher(b)
	if err != nil {
		return nil, err
	}
	return &aesgcm{block: block}, nil
}