package ch.qos.logback.classic.servlet;
   
   import static ch.qos.logback.core.CoreConstants.DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY;
   
   import java.util.Set;
   
   import jakarta.servlet.ServletContainerInitializer;
   import jakarta.servlet.ServletContext;
   import jakarta.servlet.ServletException;
  
  import ch.qos.logback.classic.util.StatusViaSLF4JLoggerFactory;
  import ch.qos.logback.core.util.OptionHelper;
  
  /**
   * Attaches a new instance of {@link LogbackServletContextListener} to the
   * current web-applications {@link ServletContext}.
   * 
   * @author Ceki Gulcu
   * @since 1.1.10
   */
  public class LogbackServletContainerInitializer implements ServletContainerInitializer {
  
      @Override
      public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException {
  
          if (isDisabledByConfiguration(ctx)) {
              StatusViaSLF4JLoggerFactory.addInfo("Due to deployment instructions will NOT register an instance of "
                      + LogbackServletContextListener.class + " to the current web-app", this);
  
              return;
          }
  
          StatusViaSLF4JLoggerFactory.addInfo(
                  "Adding an instance of  " + LogbackServletContextListener.class + " to the current web-app", this);
          LogbackServletContextListener lscl = new LogbackServletContextListener();
          ctx.addListener(lscl);
      }
  
      /**
       * Search for value of DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY in the web-app
       * first, then as a system property and as an environment variable last.
       *
       * @param ctx
       * @return True if value of DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY is
       *         available and set to "true", false otherwise.
       */
      boolean isDisabledByConfiguration(ServletContext ctx) {
          String disableAttributeStr = null;
          Object disableAttribute = ctx.getInitParameter(DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY);
          if (disableAttribute instanceof String) {
              disableAttributeStr = (String) disableAttribute;
          }
  
          if (OptionHelper.isNullOrEmptyOrAllSpaces(disableAttributeStr)) {
              disableAttributeStr = OptionHelper.getSystemProperty(DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY);
          }
  
          if (OptionHelper.isNullOrEmptyOrAllSpaces(disableAttributeStr)) {
              disableAttributeStr = OptionHelper.getEnv(DISABLE_SERVLET_CONTAINER_INITIALIZER_KEY);
          }
  
          return Boolean.parseBoolean(disableAttributeStr);
      }
  
  }