# frozen_string_literal: true

require 'safe_yaml'

SafeYAML::OPTIONS[:default_mode] = :safe

module NoradBeacon
  class ContainerOptions
    CONTAINERS_FILE_URI = '/containers.yml.enc'
    AES_KEY_SIZE = 128
    attr_reader :values

    def initialize
      @values = File.exist?(CONTAINERS_FILE_URI) ? decrypt_and_load : {}
    end

    private

    # Reads encrypted credentials from disk, decrypts the
    # credentials, and loads and returns the YAML.
    # @return [Hash]
    def decrypt_and_load
      aes_key = load_key_from_env
      symbolize YAML.safe_load(decrypt_containers_file(aes_key))
    rescue Psych::SyntaxError
      raise NoradBeaconError, e.message
    end

    # Load the Base64 encoded key from the environment
    # @return [String] AES Key
    def load_key_from_env
      Base64.strict_decode64(ENV.fetch('NORAD_CONTAINERS_FILE_KEY'))
    rescue ArgumentError => e
      raise NoradBeaconError, e.message
    end

    # Decrypt the contents of the containers options file
    # @param aes_key [String]
    # @return [String] decrypted contents of the file
    def decrypt_containers_file(aes_key)
      decipher = OpenSSL::Cipher::AES.new(AES_KEY_SIZE, :CBC)
      decipher.decrypt
      decipher.key = aes_key
      encrypted_data = File.read(CONTAINERS_FILE_URI, mode: 'rb')
      decipher.iv = encrypted_data[0..16] # First 16 bytes of this file is the IV
      decipher.update(encrypted_data[16..-1]) + decipher.final
    rescue Errno::ENOENT, OpenSSL::Cipher::CipherError => e
      raise NoradBeaconError, e.message
    end

    # Symbolize the keys for a deeply nested array
    # Adapted from ActiveSupport's implementation
    #
    # @param object [Object] some value we wish to symbolize
    # @return [Hash] a hash with symbolized keys
    def symbolize(object)
      case object
      when Hash
        object.each_with_object({}) do |(k, v), result|
          result[k.respond_to?(:to_sym) ? k.to_sym : k] = symbolize(v)
        end
      when Array
        object.map { |el| symbolize(el) }
      else
        object
      end
    end
  end
end