public interface Authentication extends Principal, Serializable {
    // 유저가 가진 권한 목록이 저장되어 있다. ex ROLE_USER, ROLE_ADMIN
    Collection<? extends GrantedAuthority> getAuthorities();

        Object getCredentials();

        Object getDetails();

        Object getPrincipal();

        boolean isAuthenticated();

        void setAuthenticated(boolean var1) throws IllegalArgumentException;
}

public interface AccessDecisionVoter<S> {
  int ACCESS_GRANTED = 1;
  int ACCESS_ABSTAIN = 0;
  int ACCESS_DENIED = -1;

  boolean supports(ConfigAttribute var1);

  boolean supports(Class<?> var1);

  /*
   * 인자 정보: Authentication: 인증 정보, S (Object): 보호받는 자원(Url로 표현되는 리소스), Collection<ConfigAttribute>: 보호받는 자원과 관련된 설정들
   * voter 구현체마다 구체적인 로직을 넣을 수 있고, 그 voter들을 Manager에 주입해서 사용하면 된다.
   */
  int vote(Authentication var1, S var2, Collection<ConfigAttribute> var3);
}

public interface AccessDecisionManager {
  void decide(Authentication var1, Object var2, Collection<ConfigAttribute> var3) throws AccessDeniedException, InsufficientAuthenticationException;

  boolean supports(ConfigAttribute var1);

  boolean supports(Class<?> var1);
}

public class AffirmativeBased extends AbstractAccessDecisionManager {
  public AffirmativeBased(List<AccessDecisionVoter<?>> decisionVoters) {
      super(decisionVoters);
    }

  public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException {
    int deny = 0;
    Iterator var5 = this.getDecisionVoters().iterator();

    while(var5.hasNext()) {
      AccessDecisionVoter voter = (AccessDecisionVoter)var5.next();
      int result = voter.vote(authentication, object, configAttributes); // voter가 투표한 결과
      if (this.logger.isDebugEnabled()) {
        this.logger.debug("Voter: " + voter + ", returned: " + result);
      }

      switch(result) {
      case -1:
        ++deny;
        break;
      case 1:
        return;
      }
    }

    if (deny > 0) {
      throw new AccessDeniedException(this.messages.getMessage("AbstractAccessDecisionManager.accessDenied", "Access is denied"));
    } else {
      this.checkAllowIfAllAbstainDecisions();
    }
  }
}

public class ConsensusBased extends AbstractAccessDecisionManager {
  public ConsensusBased(List<AccessDecisionVoter<?>> decisionVoters) {
    super(decisionVoters);
  }

  public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException {
    int grant = 0;
    int deny = 0;
    Iterator var6 = this.getDecisionVoters().iterator();

    while(var6.hasNext()) {
      AccessDecisionVoter voter = (AccessDecisionVoter)var6.next();
      int result = voter.vote(authentication, object, configAttributes);
      if (this.logger.isDebugEnabled()) {
        this.logger.debug("Voter: " + voter + ", returned: " + result);
      }

      switch(result) {
      case -1:
        ++deny;
        break;
      case 1:
        ++grant;
      }
    }

    if (grant <= deny) {
      if (deny > grant) {
        throw new AccessDeniedException(this.messages.getMessage("AbstractAccessDecisionManager.accessDenied", "Access is denied"));
      } else if (grant == deny && grant != 0) {
        if (!this.allowIfEqualGrantedDeniedDecisions) {
          throw new AccessDeniedException(this.messages.getMessage("AbstractAccessDecisionManager.accessDenied", "Access is denied"));
        }
      } else {
        this.checkAllowIfAllAbstainDecisions();
      }
    }
  }
   public void setAllowIfEqualGrantedDeniedDecisions(boolean allowIfEqualGrantedDeniedDecisions) {
    this.allowIfEqualGrantedDeniedDecisions = allowIfEqualGrantedDeniedDecisions;
  }
}

public class UnanimousBased extends AbstractAccessDecisionManager {
  public UnanimousBased(List<AccessDecisionVoter<?>> decisionVoters) {
    super(decisionVoters);
  }

  public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> attributes) throws AccessDeniedException {
    int grant = 0;
    List<ConfigAttribute> singleAttributeList = new ArrayList(1);
    singleAttributeList.add((Object)null);
    Iterator var6 = attributes.iterator();

    while(var6.hasNext()) {
      ConfigAttribute attribute = (ConfigAttribute)var6.next();
      singleAttributeList.set(0, attribute);
      Iterator var8 = this.getDecisionVoters().iterator();

      while(var8.hasNext()) {
        AccessDecisionVoter voter = (AccessDecisionVoter)var8.next();
        int result = voter.vote(authentication, object, singleAttributeList);
        if (this.logger.isDebugEnabled()) {
          this.logger.debug("Voter: " + voter + ", returned: " + result);
        }

        switch(result) {
        case -1:
          throw new AccessDeniedException(this.messages.getMessage("AbstractAccessDecisionManager.accessDenied", "Access is denied"));
        case 1:
          ++grant;
        }
      }
    }

    if (grant <= 0) {
      this.checkAllowIfAllAbstainDecisions();
    }
  }
}

@Configuration
@EnableWebSecurity
public class WebSecurityConfigure extends WebSecurityConfigurerAdapter {

  @Override
    protected void configure(HttpSecurity http) throws Exception {
      http
        .csrf()
          .disable()
        .headers()
          .disable()
        .exceptionHandling() // 예외 핸들러 등록
          .accessDeniedHandler(accessDeniedHandler) // accessDeniedHandler()는 권한 체크에서 실패할 때 수행되는 핸들러
          .authenticationEntryPoint(unauthorizedHandler)  // authenticationEntryPoint()는 인증되지 않은 사용자가 보호된 리소스에 접근했을 때 수행되는 핸들러
          .and()
        .sessionManagement()
          .sessionCreationPolicy(SessionCreationPolicy.STATELESS)
          .and()
        .authorizeRequests() // URL별 권한 관리 설정
          .antMatchers("/api/auth").permitAll()
          .antMatchers("/api/user/join").permitAll()
          .antMatchers("/api/**").hasRole(Role.USER.name())
          .accessDecisionManager(accessDecisionManager()) // 사용할 accessDecisionManager 주입 (커스터마이징)
          .anyRequest().permitAll()
          .and()
        .formLogin()
          .disable();
      http
        .addFilterBefore(jwtAuthenticationTokenFilter(), UsernamePasswordAuthenticationFilter.class); // 사용자 정의 필터
	}
}

@Bean
public AccessDecisionManager accessDecisionManager() {
  List<AccessDecisionVoter<?>> decisionVoters = new ArrayList<>();
  decisionVoters.add(new WebExpressionVoter());
  decisionVoters.add(connectionBasedVoter()); // 직접 구현한 voter
  return new UnanimousBased(decisionVoters);
}