class Dry::Schema::KeyValidator

def call(result)
  input = result.to_h
  input_paths = key_paths(input)
  key_paths = key_map.to_dot_notation
  input_paths.each do |path|
    error_path =
      if path[INDEX_REGEX]
        key = path.gsub(INDEX_REGEX, BRACKETS)
        unless key_paths.include?(key)
          arr = path.gsub(INDEX_REGEX) { |m| ".#{m[1]}" }
          arr.split(DOT).map { |s| DIGIT_REGEX.match?(s) ? s.to_i : s.to_sym }
        end
      elsif !key_paths.include?(path)
        path
      end
    next unless error_path
    result.add_error([:unexpected_key, [error_path, input]])
  end
  result
end

def key_paths(hash)
  hash.flat_map { |key, _|
    case (value = hash[key])
    when Hash
      [key].product(key_paths(hash[key])).map { |keys| keys.join(DOT) }
    when Array
      value.flat_map.with_index { |el, idx|
        key_paths(el).map { |path| ["#{key}[#{idx}]", *path].join(DOT) }
      }
    else
      key.to_s
    end
  }
end