SpringSecurity authorize tag support for Handlebars

Authorize.hbs

{{#partial "content" }}
<div class="lc-block">
		<h1>Hello World!</h1>
		<div>
			Click <a href="/hello">here</a> to see a greeting.
			{{#authorize "hasRole('ROLE_USER')"}}
			This is login user!!
			{{/authorize}}
			{{#authorize "isAnonymous()"}}
			now anonymous
			{{/authorize}}
		</div>
	</div>
{{/partial}}

SpringSecurityHelper.java

import com.github.jknack.handlebars.Helper;
import com.github.jknack.handlebars.Options;
import com.github.jknack.handlebars.Options.Buffer;
import lombok.extern.slf4j.Slf4j;
import org.jetbrains.annotations.NotNull;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.core.GenericTypeResolver;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.ParseException;
import org.springframework.security.access.expression.ExpressionUtils;
import org.springframework.security.access.expression.SecurityExpressionHandler;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.web.FilterInvocation;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.annotation.PostConstruct;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import java.util.Map;

@Component
@Slf4j
public class SpringSecurityHelper implements Helper<Object> {
    public static final String NAME = "authorize";

    @Autowired
    private ApplicationContext context;

    private SecurityExpressionHandler securityExpressionHandler;

    @PostConstruct
    public void init() throws IOException {
        securityExpressionHandler = getExpressionHandler();
    }

    @Override
    public Object apply(Object context, Options options) throws IOException {
        LOGGER.debug("context : {}", context);

        Buffer buffer = options.buffer();

        if (evaluateAuthority(context.toString())) {
            buffer.append(options.fn());
        } else {
            buffer.append(options.inverse());
        }

        return buffer;
    }

    private boolean evaluateAuthority(String access) throws IOException {
        if (SecurityContextHolder.getContext().getAuthentication() == null) {
            return false;
        }

        return ExpressionUtils.evaluateAsBoolean(getAccessExpression(access), createExpressionEvaluationContext());
    }

    private EvaluationContext createExpressionEvaluationContext() {
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        FilterInvocation invocation = new FilterInvocation(attributes.getRequest(), attributes.getResponse(), new FilterChain() {
            @Override
            public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {
                throw new UnsupportedOperationException();
            }
        });

        return securityExpressionHandler.createEvaluationContext(SecurityContextHolder.getContext().getAuthentication(), invocation);
    }

    @NotNull
    private Expression getAccessExpression(String access) throws IOException {
        Expression accessExpression = null;

        try {
            accessExpression = securityExpressionHandler.getExpressionParser().parseExpression(access);
        } catch (ParseException e) {
            IOException ioException = new IOException();
            ioException.initCause(e);

            throw ioException;
        }

        return accessExpression;
    }

    private SecurityExpressionHandler<FilterInvocation> getExpressionHandler() throws IOException {
        Map<String, SecurityExpressionHandler> handlerMap = context.getBeansOfType(SecurityExpressionHandler.class);

        for (SecurityExpressionHandler handler : handlerMap.values()) {
            if (FilterInvocation.class.equals(GenericTypeResolver.resolveTypeArgument(handler.getClass(), SecurityExpressionHandler.class))) {
                return handler;
            }
        }

        throw new IOException("No visible WebSecurityExpressionHandler instance could be found in the application");
    }
}

WebMVCConfig.java

@Configuration
@ConditionalOnClass(HandlebarsViewResolver.class)
public class WebMVCConfig {
    @Configuration
    @ConditionalOnClass(SpringSecurityHelper.class)
    static class SpringSecurityHelperAutoConfiguration {
        @Autowired
        private HandlebarsViewResolver handlebarsViewResolver;

        @Autowired
        private SpringSecurityHelper springSecurityHelper;

        @PostConstruct
        public void registerHelper() {
            handlebarsViewResolver.registerHelper(SpringSecurityHelper.NAME, springSecurityHelper);
        }
    }
}