[기타] enum 활용법

Spring Security / JWT 에 대한 자료를 찾아보다 아래와 같은 코드를 발견

public enum OAuthAttributes {
    GITHUB("github", (attributes) -> {
        return new UserProfile(
                String.valueOf(attributes.get("id")),
                (String) attributes.get("name"),
                (String) attributes.get("email"),
                (String) attributes.get("avatar_url")
        );
    }),
    GOOGLE("google", (attributes) -> {
        return new UserProfile(
                String.valueOf(attributes.get("sub")),
                (String) attributes.get("name"),
                (String) attributes.get("email"),
                (String) attributes.get("picture")
        );
    }),
    NAVER("naver", (attributes) -> {
        Map<String, Object> response = (Map<String, Object>) attributes.get("response");
        return new UserProfile(
                (String) response.get("id"),
                (String) response.get("name"),
                (String) response.get("email"),
                (String) response.get("profile_image")
        );
    });

    private final String registrationId;
    private final Function<Map<String, Object>, UserProfile> of;

    OAuthAttributes(String registrationId, Function<Map<String, Object>, UserProfile> of) {
        this.registrationId = registrationId;
        this.of = of;
    }

    public static UserProfile extract(String registrationId, Map<String, Object> attributes) {
        return Arrays.stream(values())
                     .filter(provider -> registrationId.equals(provider.registrationId))
                     .findFirst()
                     .orElseThrow(IllegalArgumentException::new)
                .of.apply(attributes);
    }
}