require 'base64'
require 'digest'
require 'openssl'
require 'optparse'

module EdgeCastToken
  class Token
    def self.encrypt(key, token)
      digest = Digest::SHA256.digest(key)
      cipher = OpenSSL::Cipher::AES.new(256, :GCM).encrypt
      iv = cipher.random_iv
      cipher.iv = iv
      cipher.key = digest
      cipher_text = cipher.update(token) + cipher.final
      cipher_with_iv = iv + cipher_text + cipher.auth_tag
      Base64.urlsafe_encode64(cipher_with_iv)
    end

    def self.decrypt(key, token)
      digest = Digest::SHA256.digest(key)
      decoded_token = Base64.urlsafe_decode64(token)
      iv = decoded_token[0..11]
      decipher_text = decoded_token[12..decoded_token.length-17]
      decipher = OpenSSL::Cipher::AES.new(256, :GCM).decrypt
      decipher.iv = iv
      decipher.key = digest
      decipher.update(decipher_text)
    end
  end
end