class Argon2::Engine

def self.argon2_verify(pwd, hash, secret)
  secretlen = secret.nil? ? 0 : secret.bytesize
  passwordlen = pwd.nil? ? 0 : pwd.bytesize
  ret = Ext.wrap_argon2_verify(hash, pwd, passwordlen, secret, secretlen)
  return false if ERRORS[ret.abs] == 'ARGON2_DECODING_FAIL'
  raise ArgonHashFail, ERRORS[ret.abs] unless ret.zero?
  true
end

def self.hash_argon2i(password, salt, t_cost, m_cost, out_len = nil)
  out_len = (out_len || Constants::OUT_LEN).to_i
  raise ArgonHashFail, "Invalid output length" if out_len < 1
  result = ''
  FFI::MemoryPointer.new(:char, out_len) do |buffer|
    ret = Ext.argon2i_hash_raw(t_cost, 1 << m_cost, 1, password,
                               password.length, salt, salt.length,
                               buffer, out_len)
    raise ArgonHashFail, ERRORS[ret.abs] unless ret.zero?
    result = buffer.read_string(out_len)
  end
  result.unpack('H*').join
end

def self.hash_argon2id(password, salt, t_cost, m_cost, p_cost, out_len = nil)
  out_len = (out_len || Constants::OUT_LEN).to_i
  raise ArgonHashFail, "Invalid output length" if out_len < 1
  result = ''
  FFI::MemoryPointer.new(:char, out_len) do |buffer|
    ret = Ext.argon2id_hash_raw(t_cost, 1 << m_cost, p_cost, password,
                                password.length, salt, salt.length,
                                buffer, out_len)
    raise ArgonHashFail, ERRORS[ret.abs] unless ret.zero?
    result = buffer.read_string(out_len)
  end
  result.unpack('H*').join
end

def self.hash_argon2id_encode(password, salt, t_cost, m_cost, p_cost, secret)
  result = ''
  secretlen = secret.nil? ? 0 : secret.bytesize
  passwordlen = password.nil? ? 0 : password.bytesize
  raise ArgonHashFail, "Invalid salt size" if salt.length != Constants::SALT_LEN
  FFI::MemoryPointer.new(:char, Constants::ENCODE_LEN) do |buffer|
    ret = Ext.argon2_wrap(buffer, password, passwordlen,
                          salt, salt.length, t_cost, (1 << m_cost),
                          p_cost, secret, secretlen)
    raise ArgonHashFail, ERRORS[ret.abs] unless ret.zero?
    result = buffer.read_string(Constants::ENCODE_LEN)
  end
  result.delete "\0"
end

def self.saltgen
  SecureRandom.random_bytes(Argon2::Constants::SALT_LEN)
end