/*
    * Licensed under the GPL License. You may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *   https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
    *
    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
    * PURPOSE.
   */
  package psiprobe.beans.stats.collectors;
  
  import jakarta.inject.Inject;
  import jakarta.servlet.ServletContext;
  
  import org.apache.catalina.Context;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.web.context.ServletContextAware;
  
  import psiprobe.TomcatContainer;
  import psiprobe.beans.ContainerWrapperBean;
  import psiprobe.model.Application;
  import psiprobe.tools.ApplicationUtils;
  import psiprobe.tools.TimeExpression;
  
  /**
   * Collects application statistics.
   */
  public class AppStatsCollectorBean extends AbstractStatsCollectorBean
      implements ServletContextAware {
  
    /** The Constant logger. */
    private static final Logger logger = LoggerFactory.getLogger(AppStatsCollectorBean.class);
  
    /** The container wrapper. */
    @Inject
    private ContainerWrapperBean containerWrapper;
  
    /** The servlet context. */
    @Inject
    private ServletContext servletContext;
  
    /** The self ignored. */
    @Value("${psiprobe.beans.stats.collectors.app.selfIgnored}")
    private boolean selfIgnored;
  
    @Override
    public void collect() throws InterruptedException {
  
      long currentTime = System.currentTimeMillis();
  
      if (containerWrapper == null) {
        logger.error("Cannot collect application stats. Container wrapper is not set.");
      } else {
        TomcatContainer tomcatContainer = containerWrapper.getTomcatContainer();
  
        // check if the containerWtapper has been initialized
        if (tomcatContainer != null) {
          long totalReqDelta = 0;
          long totalErrDelta = 0;
          long totalAvgProcTime = 0;
          int participatingAppCount = 0;
  
          for (Context ctx : tomcatContainer.findContexts()) {
            if (ctx != null && ctx.getName() != null) {
              Application app = new Application();
              ApplicationUtils.collectApplicationServletStats(ctx, app);
  
              String appName = ctx.getName().isEmpty() ? "/" : ctx.getName();
  
              long reqDelta =
                  buildDeltaStats("app.requests." + appName, app.getRequestCount(), currentTime);
              long errDelta = buildDeltaStats("app.errors." + appName, app.getErrorCount());
              long procTimeDelta =
                  buildDeltaStats("app.proc_time." + appName, app.getProcessingTime(), currentTime);
  
              long avgProcTime = reqDelta == 0 ? 0 : procTimeDelta / reqDelta;
              buildAbsoluteStats("app.avg_proc_time." + appName, avgProcTime, currentTime);
  
              /*
               * make sure applications that did not serve any requests do not participate in average
               * response time equation thus diluting the value
               */
              if (reqDelta > 0 && !excludeFromTotal(ctx)) {
                totalReqDelta += reqDelta;
                totalErrDelta += errDelta;
                totalAvgProcTime += avgProcTime;
                participatingAppCount++;
              }
            }
          }
          // build totals for all applications
          buildAbsoluteStats("total.requests", totalReqDelta, currentTime);
          buildAbsoluteStats("total.errors", totalErrDelta, currentTime);
          buildAbsoluteStats("total.avg_proc_time",
              participatingAppCount == 0 ? 0 : totalAvgProcTime / participatingAppCount, currentTime);
        }
       logger.debug("app stats collected in {}ms", System.currentTimeMillis() - currentTime);
     }
   }
 
   /**
    * Exclude from total.
    *
    * @param ctx the ctx
    *
    * @return true, if successful
    */
   private boolean excludeFromTotal(Context ctx) {
     return selfIgnored && servletContext.equals(ctx.getServletContext());
   }
 
   /**
    * Reset.
    */
   public void reset() {
     if (containerWrapper == null) {
       logger.error("Cannot reset application stats. Container wrapper is not set.");
     } else {
       TomcatContainer tomcatContainer = containerWrapper.getTomcatContainer();
       if (tomcatContainer != null) {
         for (Context ctx : tomcatContainer.findContexts()) {
           if (ctx != null && ctx.getName() != null) {
             String appName = ctx.getName().isEmpty() ? "/" : ctx.getName();
             reset(appName);
           }
         }
       }
     }
     resetStats("total.requests");
     resetStats("total.errors");
     resetStats("total.avg_proc_time");
   }
 
   /**
    * Reset.
    *
    * @param appName the app name
    */
   public void reset(String appName) {
     resetStats("app.requests." + appName);
     resetStats("app.proc_time." + appName);
     resetStats("app.errors." + appName);
     resetStats("app.avg_proc_time." + appName);
   }
 
   /**
    * Sets the max series expression.
    *
    * @param period the period
    * @param span the span
    */
   public void setMaxSeries(@Value("${psiprobe.beans.stats.collectors.app.period}") String period,
       @Value("${psiprobe.beans.stats.collectors.app.span}") String span) {
     super.setMaxSeries((int) TimeExpression.dataPoints(period, span));
   }
 
   @Override
   public void setServletContext(ServletContext servletContext) {
     // Do not set servlet context as set via injection
   }
 
 }