DemoApplication.java

package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.UUID;
import java.util.function.Function;

@ComponentScan
@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

    @RestController
    @RequestMapping("/api")
    public static class ApiController {

        public AwesomeContext AwesomeAction(CallContext ctx) {
            System.out.println("log before ... " + ctx.request.getRequestURI());
            return new AwesomeContext(UUID.randomUUID().toString(), ctx);
        }

        @GetMapping("/hello")
        public String home() {
            return Actions.with(this::AwesomeAction).run(ctx -> {
                System.out.println(ctx.innerCtx.request.getMethod() + " method on " + ctx.innerCtx.request.getRequestURI());
                return "hello";
            });
        }
    }

    public static class AwesomeContext {
	    public final CallContext innerCtx;
	    public final String reqId;
        public AwesomeContext(String reqId, CallContext ctx) {
            this.reqId = reqId;
            this.innerCtx = ctx;
        }
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // API part  
    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    @Component
    static class Helper {

        private static WebApplicationContext webApplicationContext;

        static WebApplicationContext webApplicationContext() {
            return webApplicationContext;
        }

        @Autowired
        public void setWebApplicationContext(WebApplicationContext webApplicationContext) {
            Helper.webApplicationContext = webApplicationContext;
        }
    }

    public static class CallContext {
        public final HttpServletRequest request;
        public final HttpServletResponse response;
        public final WebApplicationContext webApplicationContext;

        public CallContext(HttpServletRequest request, HttpServletResponse response, WebApplicationContext webApplicationContext) {
            this.request = request;
            this.response = response;
            this.webApplicationContext = webApplicationContext;
        }
    }

    public static class ActionChain<In> {

	    private final Function<CallContext, In> chain;

        public ActionChain(Function<CallContext, In> chain) {
            this.chain = chain;
        }

        public <Ret> Ret run(Function<In, Ret> block) {
            RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
            if (requestAttributes instanceof ServletRequestAttributes) {
                ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) requestAttributes;
                HttpServletRequest request = servletRequestAttributes.getRequest();
                HttpServletResponse response = servletRequestAttributes.getResponse();
                return block.apply(chain.apply(new CallContext(request, response, Helper.webApplicationContext())));
            } else {
                throw new RuntimeException("WTF ???");
            }
        }
    }

    public static class Actions {
	    public static <Ret> ActionChain<Ret> with(Function<CallContext, Ret> action) {
            return new ActionChain<Ret>(action);
        }
        public static <Ret1, Ret2> ActionChain<Ret2> combine(
            Function<CallContext, Ret1> action1,
            Function<Ret1, Ret2> action2
        ) {
            return new ActionChain<Ret2>(action1.andThen(action2));
        }
        public static <Ret1, Ret2, Ret3> ActionChain<Ret3> combine(
                Function<CallContext, Ret1> action1,
                Function<Ret1, Ret2> action2,
                Function<Ret2, Ret3> action3
        ) {
            return new ActionChain<Ret3>(action1.andThen(action2).andThen(action3));
        }
        public static <Ret1, Ret2, Ret3, Ret4> ActionChain<Ret4> combine(
                Function<CallContext, Ret1> action1,
                Function<Ret1, Ret2> action2,
                Function<Ret2, Ret3> action3,
                Function<Ret3, Ret4> action4
        ) {
            return new ActionChain<Ret4>(action1.andThen(action2).andThen(action3).andThen(action4));
        }
        public static <Ret1, Ret2, Ret3, Ret4, Ret5> ActionChain<Ret5> combine(
                Function<CallContext, Ret1> action1,
                Function<Ret1, Ret2> action2,
                Function<Ret2, Ret3> action3,
                Function<Ret3, Ret4> action4,
                Function<Ret4, Ret5> action5
        ) {
            return new ActionChain<Ret5>(action1.andThen(action2).andThen(action3).andThen(action4).andThen(action5));
        }
    }
}