Facti13.Web.Backend.Java.V2/src/main/java/app/annotations/impl/ClusterMethodAspect.java

package app.annotations.impl;

import app.updates.BaseUpdater;
import jakarta.annotation.PostConstruct;
import jakarta.servlet.http.HttpServletRequest;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.event.EventListener;
import org.springframework.core.env.Environment;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.web.client.RestTemplate;

import java.io.ByteArrayInputStream;
import java.io.ObjectInputStream;
import java.time.Instant;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.function.Supplier;

@Aspect
@Configuration
public class ClusterMethodAspect extends BaseUpdater {

    @Autowired
    private HttpServletRequest httpServletRequest;
    private final HashMap<String, Long> lastClusterPulse = new HashMap<>();

    private final RestTemplate restTemplate;
    private final String[] clusters;
    private final Logger logger = LoggerFactory.getLogger(getClass());
    private final Long max_range = 15L;

    @Autowired
    public ClusterMethodAspect(Environment environment) {
        this.restTemplate = new RestTemplate();
        this.clusters = environment.getProperty("CLUSTERS","").isEmpty() ? new String[0] : environment.getProperty("CLUSTERS","").split(",");
        if (this.clusters.length > 0) {
            for (int i = 0; i < this.clusters.length; i++) {
                this.logger.info("[Clusters init] found {} host", this.clusters[i]);
            }
        } else {
            this.logger.warn("[Clusters init] not found clusters");
        }
    }

    @After("@annotation(app.annotations.interfaces.ClusterMethod)")
    public void after() {
        try {
            this.sendData(httpServletRequest);
        } catch (Exception e) {
            logger.error("Cannot create data to send to other clusters", e);
        }
    }

    private void sendData(HttpServletRequest request) {
        if (clusters.length > 0) {
            ExecutorService executor = Executors.newFixedThreadPool(clusters.length);
            Set<Callable<Supplier>> callables = new HashSet<>(clusters.length);

            ClusterRequest clusterRequest = new ClusterRequest(request);

            for(int i = 0; i < clusters.length; i++) {
                int finalI = i;
                callables.add(() -> {
                    if (lastClusterPulse.containsKey(clusters[finalI]) && Instant.now().getEpochSecond() - lastClusterPulse.get(clusters[finalI]) > max_range) {
                        this.logger.warn("Cannot redirect packet to cluster {}, he is ded more {} seconds", clusters[finalI], max_range);
                        return null;
                    }

                    try {
                        restTemplate.exchange("http://" + clusters[finalI] + clusterRequest.getUrl(), clusterRequest.getHttpMethod(), clusterRequest.getHttpEntity(clusters[finalI]), byte[].class);
                    } catch (Exception e) {
                        logger.error("Cannot send info to cluster {}", clusters[finalI], e);
                    }

                    return null;
                });
            }

            try {
                executor.invokeAll(callables);
            } catch (InterruptedException ie) {}
            finally {
                executor.shutdown();
            }
        }
    }

    @EventListener(ApplicationReadyEvent.class)
    private void createClustersChecker() {
        for(int i = 0; i < clusters.length; i++) {
            int finalI = i;
            this.logger.info("Create cluster pulse check on {}", clusters[finalI]);
            CreateTaskUpdater(() -> checkCluster(clusters[finalI]), 1000, getClass().getName());
        }
    }

    private boolean checkCluster(String address) {
        try {
            restTemplate.getForEntity("http://" + address + "/api/pulse/db", Long.class).getBody();
            lastClusterPulse.put(address, Instant.now().getEpochSecond());
            return true;
        } catch (Exception err) {
            this.logger.error("Cannot pulse {}", address);
            return false;
        } finally {
            if (lastClusterPulse.containsKey(address)) {
                long range = Instant.now().getEpochSecond() - lastClusterPulse.get(address);
                if (range > max_range) {
                    this.logger.warn("Cannot pulse {} more {} seconds", address, range);
                }
            }
        }
    }

    class ClusterRequest {
        private final String url;
        private final HttpHeaders httpHeaders;
        private Object body;
        private final HttpMethod httpMethod;

        public ClusterRequest(HttpServletRequest httpServletRequest) {
            StringBuilder url = new StringBuilder();
            url.append(httpServletRequest.getRequestURI());
            if (httpServletRequest.getQueryString() != null) {
                url.append("?");
                url.append(httpServletRequest.getQueryString());
            }
            this.url = url.toString();

            httpHeaders = new HttpHeaders();
            httpServletRequest.getHeaderNames().asIterator().forEachRemaining(
                    (headerName) -> httpHeaders.set(headerName, httpServletRequest.getHeader(headerName))
            );

            try (ObjectInputStream is = new ObjectInputStream(httpServletRequest.getInputStream())) {
                body = is.readObject();
            } catch (Exception e) {}

            httpMethod = HttpMethod.valueOf(httpServletRequest.getMethod());
        }

        public String getUrl() {
            return url;
        }

        public Object getBody() {
            return body;
        }

        public HttpMethod getHttpMethod() {
            return httpMethod;
        }

        public HttpEntity getHttpEntity(String cluster) {
            httpHeaders.set("F13-TO-CLUSTER", cluster);
            return new HttpEntity(body, httpHeaders);
        }
    }
}