package com.ctrip.apollo.portal;

 import java.util.ArrayList;

 import java.util.HashMap;

 import java.util.LinkedList;

 import java.util.List;

 import java.util.Map;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.Executors;

 import java.util.concurrent.ScheduledExecutorService;

 import java.util.concurrent.TimeUnit;

 import javax.annotation.PostConstruct;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 import org.springframework.beans.factory.annotation.Autowired;

 import org.springframework.beans.factory.annotation.Value;

 import org.springframework.boot.actuate.health.Health;

 import org.springframework.context.ApplicationContext;

 import org.springframework.stereotype.Component;

 import com.ctrip.apollo.core.enums.Env;

 import com.ctrip.apollo.portal.api.AdminServiceAPI;

 @Component

 public class PortalSettings {

   private Logger logger = LoggerFactory.getLogger(PortalSettings.class);

   private static final int HEALTH_CHECK_INTERVAL = 5000;

   @Value("#{'${apollo.portal.env}'.split(',')}")

   private List<String> allStrEnvs;

   @Autowired

   ApplicationContext applicationContext;

   private List<Env> allEnvs = new ArrayList<Env>();

   private List<Env> activeEnvs;

   //mark env up or down

   private Map<Env, Boolean> envStatusMark = new ConcurrentHashMap<>();

   private ScheduledExecutorService healthCheckService;

   @PostConstruct

   private void postConstruct() {

     //init origin config envs

     for (String e : allStrEnvs) {

       allEnvs.add(Env.valueOf(e.toUpperCase()));

     }

     for (Env env : allEnvs) {

       envStatusMark.put(env, true);

     }

     healthCheckService = Executors.newScheduledThreadPool(1);

     healthCheckService

         .scheduleWithFixedDelay(new HealthCheckTask(applicationContext), 1000, HEALTH_CHECK_INTERVAL,

                                 TimeUnit.MILLISECONDS);

   }

   public List<Env> getActiveEnvs() {

     List<Env> activeEnvs = new LinkedList<>();

     for (Env env : allEnvs) {

       if (envStatusMark.get(env)) {

         activeEnvs.add(env);

       }

     }

     this.activeEnvs = activeEnvs;

     return activeEnvs;

   }

   public Env getFirstAliveEnv() {

     return activeEnvs.get(0);

   }

   class HealthCheckTask implements Runnable {

     private static final int ENV_DIED_THREADHOLD = 2;

     private Map<Env, Long> healthCheckFailCnt = new HashMap<>();

     private AdminServiceAPI.HealthAPI healthAPI;

     public HealthCheckTask(ApplicationContext context) {

       healthAPI = context.getBean(AdminServiceAPI.HealthAPI.class);

       for (Env env : allEnvs) {

         healthCheckFailCnt.put(env, 0l);

       }

     }

     public void run() {

       for (Env env : allEnvs) {

         try {

           if (isUp(env)) {

             //revive

             if (!envStatusMark.get(env)) {

               envStatusMark.put(env, true);

               healthCheckFailCnt.put(env, 0l);

               logger.info("env up again [env:{}]", env);

             }

           } else {

             //maybe meta server up but admin server down

             handleEnvDown(env);

           }

         } catch (Exception e) {

           //maybe meta server down

           logger.warn("health check fail. [env:{}]", env, e.getMessage());

           handleEnvDown(env);

         }

       }

     }

     private boolean isUp(Env env) {

       Health health = healthAPI.health(env);

       return "UP".equals(health.getStatus().getCode());

     }

     private void handleEnvDown(Env env) {

       long failCnt = healthCheckFailCnt.get(env);

       healthCheckFailCnt.put(env, ++failCnt);

       if (!envStatusMark.get(env)) {

         logger.warn("[env:{}] down yet.", env);

       } else {

         if (failCnt >= ENV_DIED_THREADHOLD) {

           envStatusMark.put(env, false);

           logger.error("env turn to down [env:{}]", env);

         } else {

           logger.warn("env health check fail first time. [env:{}]", env);

         }

       }

     }

   }

 }