/**
   * Generates a new instance of an anonymous inner class that implements the PageNode interface.
   *
   * @param pageClass The class providing the widget content for the page.
   * @param pageName The name of the page (to be used in the URL history fragment).
   */
  private ObjectBuilder generateNewInstanceOfPageImpl(MetaClass pageClass, String pageName) {
    AnonymousClassStructureBuilder pageImplBuilder =
        ObjectBuilder.newInstanceOf(
                MetaClassFactory.parameterizedAs(
                    PageNode.class, MetaClassFactory.typeParametersOf(pageClass)))
            .extend();

    pageImplBuilder
        .publicMethod(String.class, "name")
        .append(Stmt.loadLiteral(pageName).returnValue())
        .finish()
        .publicMethod(Class.class, "contentType")
        .append(Stmt.loadLiteral(pageClass).returnValue())
        .finish()
        .publicMethod(
            void.class, "produceContent", Parameter.of(CreationalCallback.class, "callback"))
        .append(
            Stmt.nestedCall(Refs.get("bm"))
                .invoke("lookupBean", Stmt.loadLiteral(pageClass))
                .invoke("getInstance", Stmt.loadVariable("callback")))
        .finish();

    appendPageHidingMethod(pageImplBuilder, pageClass);
    appendPageHiddenMethod(pageImplBuilder, pageClass);

    appendPageShowingMethod(pageImplBuilder, pageClass);
    appendPageShownMethod(pageImplBuilder, pageClass);

    return pageImplBuilder.finish();
  }
  /**
   * Appends the method that calls the {@code @PageHiding} method of the widget.
   *
   * @param pageImplBuilder The class builder for the implementation of PageNode we are adding the
   *     method to.
   * @param pageClass The "content type" (Widget subclass) of the page. This is the type the user
   *     annotated with {@code @Page}.
   */
  private void appendPageHidingMethod(
      AnonymousClassStructureBuilder pageImplBuilder, MetaClass pageClass) {
    BlockBuilder<?> method =
        pageImplBuilder
            .publicMethod(
                void.class,
                createMethodNameFromAnnotation(PageHiding.class),
                Parameter.of(pageClass, "widget"),
                Parameter.of(NavigationControl.class, "control"))
            .body();
    final MetaMethod pageHidingMethod =
        checkMethodAndAddPrivateAccessors(
            pageImplBuilder,
            method,
            pageClass,
            PageHiding.class,
            NavigationControl.class,
            "control");

    /*
     * If the user did not provide a control parameter, we must proceed for them after the method is invoked.
     */
    if (pageHidingMethod == null || pageHidingMethod.getParameters().length != 1) {
      method.append(Stmt.loadVariable("control").invoke("proceed"));
    }

    method.finish();
  }
  /**
   * Appends the method that calls the {@code @PageHidden} method of the widget.
   *
   * @param pageImplBuilder The class builder for the implementation of PageNode we are adding the
   *     method to.
   * @param pageClass The "content type" (Widget subclass) of the page. This is the type the user
   *     annotated with {@code @Page}.
   */
  private void appendPageHiddenMethod(
      AnonymousClassStructureBuilder pageImplBuilder, MetaClass pageClass) {
    BlockBuilder<?> method =
        pageImplBuilder
            .publicMethod(
                void.class,
                createMethodNameFromAnnotation(PageHidden.class),
                Parameter.of(pageClass, "widget"))
            .body();
    checkMethodAndAddPrivateAccessors(
        pageImplBuilder, method, pageClass, PageHidden.class, HistoryToken.class, "state");

    if (pageClass.getAnnotation(Singleton.class) == null
        && pageClass.getAnnotation(ApplicationScoped.class) == null
        && pageClass.getAnnotation(EntryPoint.class) == null) {
      method.append(Stmt.loadVariable("bm").invoke("destroyBean", Stmt.loadVariable("widget")));
    }
    method.finish();
  }
  private void appendPageShowMethod(
      AnonymousClassStructureBuilder pageImplBuilder,
      MetaClass pageClass,
      Class<? extends Annotation> annotation,
      boolean addPrivateAccessors) {
    BlockBuilder<?> method =
        pageImplBuilder
            .publicMethod(
                void.class,
                createMethodNameFromAnnotation(annotation),
                Parameter.of(pageClass, "widget"),
                Parameter.of(HistoryToken.class, "state"))
            .body();

    int idx = 0;

    method.append(Stmt.declareFinalVariable("pageState", Map.class, new HashMap<String, Object>()));
    for (MetaField field : pageClass.getFieldsAnnotatedWith(PageState.class)) {
      PageState psAnno = field.getAnnotation(PageState.class);
      String fieldName = field.getName();
      String queryParamName = psAnno.value();
      if (queryParamName == null || queryParamName.trim().isEmpty()) {
        queryParamName = fieldName;
      }

      if (addPrivateAccessors) {
        PrivateAccessUtil.addPrivateAccessStubs(
            PrivateAccessType.Write, "jsni", pageImplBuilder, field, new Modifier[] {});
      }

      String injectorName = PrivateAccessUtil.getPrivateFieldInjectorName(field);

      MetaClass erasedFieldType = field.getType().getErased();
      if (erasedFieldType.isAssignableTo(Collection.class)) {
        MetaClass elementType =
            MarshallingGenUtil.getConcreteCollectionElementType(field.getType());
        if (elementType == null) {
          throw new UnsupportedOperationException(
              "Found a @PageState field with a Collection type but without a concrete type parameter. "
                  + "Collection-typed @PageState fields must specify a concrete type parameter.");
        }
        if (erasedFieldType.equals(MetaClassFactory.get(Set.class))) {
          method.append(Stmt.declareVariable(fieldName, Stmt.newObject(HashSet.class)));
        } else if (erasedFieldType.equals(MetaClassFactory.get(List.class))
            || erasedFieldType.equals(MetaClassFactory.get(Collection.class))) {
          method.append(Stmt.declareVariable(fieldName, Stmt.newObject(ArrayList.class)));
        } else {
          throw new UnsupportedOperationException(
              "Found a @PageState field which is a collection of type "
                  + erasedFieldType.getFullyQualifiedName()
                  + ". For collection-valued fields, only the exact types java.util.Collection, java.util.Set, and "
                  + "java.util.List are supported at this time.");
        }

        // for (String fv{idx} : state.get({fieldName}))
        method.append(
            Stmt.loadVariable("state")
                .invoke("getState")
                .invoke("get", queryParamName)
                .foreach("elem", Object.class)
                .append(
                    Stmt.declareVariable(
                        "fv" + idx, Stmt.castTo(String.class, Stmt.loadVariable("elem"))))
                .append(
                    Stmt.loadVariable(fieldName)
                        .invoke(
                            "add",
                            paramFromStringStatement(elementType, Stmt.loadVariable("fv" + idx))))
                .append(
                    Stmt.loadVariable("pageState")
                        .invoke("put", fieldName, Stmt.loadVariable(fieldName)))
                .finish());
        method.append(
            Stmt.loadVariable("this")
                .invoke(injectorName, Stmt.loadVariable("widget"), Stmt.loadVariable(fieldName)));
      } else {
        method.append(
            Stmt.declareFinalVariable(
                "fv" + idx,
                Collection.class,
                Stmt.loadVariable("state").invoke("getState").invoke("get", queryParamName)));
        method.append(
            If.cond(
                    Bool.or(
                        Bool.isNull(Stmt.loadVariable("fv" + idx)),
                        Stmt.loadVariable("fv" + idx).invoke("isEmpty")))
                .append(
                    Stmt.loadVariable("this")
                        .invoke(
                            injectorName,
                            Stmt.loadVariable("widget"),
                            defaultValueStatement(erasedFieldType)))
                .finish()
                .else_()
                .append(
                    Stmt.loadVariable("this")
                        .invoke(
                            injectorName,
                            Stmt.loadVariable("widget"),
                            paramFromStringStatement(
                                erasedFieldType,
                                Stmt.loadVariable("fv" + idx).invoke("iterator").invoke("next"))))
                .append(
                    Stmt.loadVariable("pageState")
                        .invoke(
                            "put",
                            fieldName,
                            Stmt.loadVariable("fv" + idx).invoke("iterator").invoke("next")))
                .finish());
      }
      idx++;
    }

    if (addPrivateAccessors) {
      method.append(
          Stmt.invokeStatic(
              CDI.class,
              "fireEvent",
              Stmt.newObject(NavigationEvent.class)
                  .withParameters(
                      Stmt.newObject(PageRequest.class)
                          .withParameters(
                              getPageName(pageClass), Stmt.loadVariable("pageState")))));
    }

    checkMethodAndAddPrivateAccessors(
        pageImplBuilder, method, pageClass, annotation, HistoryToken.class, "state");

    method.finish();
  }