# frozen_string_literal: true

require "digest/sha2"

module Authlogic
  # The acts_as_authentic method has a crypto_provider option. This allows you
  # to use any type of encryption you like. Just create a class with a class
  # level encrypt and matches? method. See example below.
  #
  # === Example
  #
  #   class MyAwesomeEncryptionMethod
  #     def self.encrypt(*tokens)
  #       # the tokens passed will be an array of objects, what type of object
  #       # is irrelevant, just do what you need to do with them and return a
  #       # single encrypted string. for example, you will most likely join all
  #       # of the objects into a single string and then encrypt that string
  #     end
  #
  #     def self.matches?(crypted, *tokens)
  #       # return true if the crypted string matches the tokens. Depending on
  #       # your algorithm you might decrypt the string then compare it to the
  #       # token, or you might encrypt the tokens and make sure it matches the
  #       # crypted string, its up to you.
  #     end
  #   end
  module CryptoProviders
    # = Sha256
    #
    # Uses the Sha256 hash algorithm to encrypt passwords.
    class Sha256
      # V2 hashes the digest bytes in repeated stretches instead of hex characters.
      autoload :V2, File.join(__dir__, "sha256", "v2")

      class << self
        attr_accessor :join_token

        # The number of times to loop through the encryption.
        def stretches
          @stretches ||= 20
        end
        attr_writer :stretches

        # Turns your raw password into a Sha256 hash.
        def encrypt(*tokens)
          digest = tokens.flatten.join(join_token)
          stretches.times { digest = Digest::SHA256.hexdigest(digest) }
          digest
        end

        # Does the crypted password match the tokens? Uses the same tokens that
        # were used to encrypt.
        def matches?(crypted, *tokens)
          encrypt(*tokens) == crypted
        end
      end
    end
  end
end
