package ch.qos.logback.classic.joran.sanity;
   
   import ch.qos.logback.classic.model.LoggerModel;
   import ch.qos.logback.classic.model.RootLoggerModel;
   import ch.qos.logback.core.joran.sanity.Pair;
   import ch.qos.logback.core.joran.sanity.SanityChecker;
   import ch.qos.logback.core.model.AppenderModel;
   import ch.qos.logback.core.model.Model;
   import ch.qos.logback.core.model.conditional.IfModel;
  import ch.qos.logback.core.spi.ContextAwareBase;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static ch.qos.logback.core.CoreConstants.CODES_URL;
  
  public class IfNestedWithinSecondPhaseElementSC extends ContextAwareBase implements SanityChecker {
  
      static final public String NESTED_IF_WARNING_URL = CODES_URL+ "#nested_if_element";
  
      @Override
      public void check(Model model) {
          if (model == null)
              return;
  
          List<Model> secondPhaseModels = new ArrayList<>();
          deepFindAllModelsOfType(AppenderModel.class, secondPhaseModels, model);
          deepFindAllModelsOfType(LoggerModel.class, secondPhaseModels, model);
          deepFindAllModelsOfType(RootLoggerModel.class, secondPhaseModels, model);
  
          List<Pair<Model, Model>> nestedPairs = deepFindNestedSubModelsOfType(IfModel.class, secondPhaseModels);
  
          if (nestedPairs.isEmpty())
              return;
  
          addWarn("<if> elements cannot be nested within an <appender>, <logger> or <root> element");
          addWarn("See also " + NESTED_IF_WARNING_URL);
          for (Pair<Model, Model> pair : nestedPairs) {
              Model p = pair.first;
              int pLine = p.getLineNumber();
              Model s = pair.second;
              int sLine = s.getLineNumber();
              addWarn("Element <"+p.getTag()+"> at line " + pLine + " contains a nested <"+s.getTag()+"> element at line " +sLine);
          }
      }
  
      @Override
      public String toString() {
          return "IfNestedWithinSecondPhaseElementSC";
      }
  }