class Epithet::Config

# File lib/epithet/config.rb, line 12
def initialize(opts = {})
  opts = opts.dup
  @separator = -String(opts.delete(:separator) { '_' })
  @context = -String(opts.delete(:context))
  alphabet = String(opts.delete(:alphabet) { Block58::Alphabet })
  @cipher = -(opts.delete(:cipher) || 'aes-256-ecb').downcase
  @digest = -(opts.delete(:digest) || 'sha256').downcase
  keygen, passphrase, scrypt = %i[keygen passphrase scrypt].map { opts.delete it }

  cipher = probe(OpenSSL::Cipher, @cipher)
  digest = probe(OpenSSL::Digest, @digest)

  raise ArgumentError, 'separator intersects alphabet' if @separator.bytes.intersect?(alphabet.bytes)
  raise ArgumentError, "#{@cipher} not a 128-bit block cipher" if cipher.block_size != 16
  raise ArgumentError, "#{@cipher} requires an IV/nonce" if cipher.iv_len != 0
  raise ArgumentError, "#{@digest} produces < 64-bit digest" if digest.digest_length < 8
  raise ArgumentError, 'use keygen: or passphrase:, not both' if keygen && (passphrase || scrypt)
  raise ArgumentError, 'one of passphrase: or keygen: is required' unless keygen || passphrase
  raise ArgumentError, "unused option(s) #{opts.keys}" unless opts.empty?

  @codec = Block58.build(cipher.block_size, alphabet:)
  @keygen = keygen || Keygen.new(passphrase:, digest: @digest, scrypt:)
  freeze
end