public static int insertClassReference(
      PsiClass psiClass, PsiFile file, int startOffset, int endOffset) {
    final Project project = file.getProject();
    PsiDocumentManager documentManager = PsiDocumentManager.getInstance(project);
    documentManager.commitAllDocuments();

    final PsiManager manager = file.getManager();

    final Document document =
        FileDocumentManager.getInstance().getDocument(file.getViewProvider().getVirtualFile());

    final PsiReference reference = file.findReferenceAt(startOffset);
    if (reference != null) {
      final PsiElement resolved = reference.resolve();
      if (resolved instanceof PsiClass) {
        if (((PsiClass) resolved).getQualifiedName() == null
            || manager.areElementsEquivalent(psiClass, resolved)) {
          return endOffset;
        }
      }
    }

    String name = psiClass.getName();
    if (name == null) {
      return endOffset;
    }

    assert document != null;
    document.replaceString(startOffset, endOffset, name);

    int newEndOffset = startOffset + name.length();
    final RangeMarker toDelete = insertTemporary(newEndOffset, document, " ");

    documentManager.commitAllDocuments();

    PsiElement element = file.findElementAt(startOffset);
    if (element instanceof PsiIdentifier) {
      PsiElement parent = element.getParent();
      if (parent instanceof PsiJavaCodeReferenceElement
          && !((PsiJavaCodeReferenceElement) parent).isQualified()
          && !(parent.getParent() instanceof PsiPackageStatement)) {
        PsiJavaCodeReferenceElement ref = (PsiJavaCodeReferenceElement) parent;

        if (psiClass.isValid()
            && !psiClass.getManager().areElementsEquivalent(psiClass, resolveReference(ref))) {
          final boolean staticImport = ref instanceof PsiImportStaticReferenceElement;
          PsiElement newElement;
          try {
            newElement =
                staticImport
                    ? ((PsiImportStaticReferenceElement) ref).bindToTargetClass(psiClass)
                    : ref.bindToElement(psiClass);
          } catch (IncorrectOperationException e) {
            return endOffset; // can happen if fqn contains reserved words, for example
          }

          final RangeMarker rangeMarker = document.createRangeMarker(newElement.getTextRange());
          documentManager.doPostponedOperationsAndUnblockDocument(document);
          documentManager.commitDocument(document);

          newElement =
              CodeInsightUtilCore.findElementInRange(
                  file,
                  rangeMarker.getStartOffset(),
                  rangeMarker.getEndOffset(),
                  PsiJavaCodeReferenceElement.class,
                  JavaLanguage.INSTANCE);
          rangeMarker.dispose();
          if (newElement != null) {
            newEndOffset = newElement.getTextRange().getEndOffset();
            if (!(newElement instanceof PsiReferenceExpression)) {
              PsiReferenceParameterList parameterList =
                  ((PsiJavaCodeReferenceElement) newElement).getParameterList();
              if (parameterList != null) {
                newEndOffset = parameterList.getTextRange().getStartOffset();
              }
            }

            if (!staticImport
                && !psiClass
                    .getManager()
                    .areElementsEquivalent(psiClass, resolveReference((PsiReference) newElement))
                && !PsiUtil.isInnerClass(psiClass)) {
              final String qName = psiClass.getQualifiedName();
              if (qName != null) {
                document.replaceString(
                    newElement.getTextRange().getStartOffset(), newEndOffset, qName);
                newEndOffset = newElement.getTextRange().getStartOffset() + qName.length();
              }
            }
          }
        }
      }
    }

    if (toDelete.isValid()) {
      document.deleteString(toDelete.getStartOffset(), toDelete.getEndOffset());
    }

    return newEndOffset;
  }
  private static Map<MethodSignature, HierarchicalMethodSignature> buildMethodHierarchy(
      PsiClass aClass,
      PsiSubstitutor substitutor,
      final boolean includePrivates,
      final Set<PsiClass> visited,
      boolean isInRawContext) {
    Map<MethodSignature, HierarchicalMethodSignature> result =
        new LinkedHashMap<MethodSignature, HierarchicalMethodSignature>();
    final Map<MethodSignature, List<PsiMethod>> sameParameterErasureMethods =
        new THashMap<MethodSignature, List<PsiMethod>>(
            MethodSignatureUtil.METHOD_PARAMETERS_ERASURE_EQUALITY);

    Map<MethodSignature, HierarchicalMethodSignatureImpl> map =
        new THashMap<MethodSignature, HierarchicalMethodSignatureImpl>(
            new TObjectHashingStrategy<MethodSignature>() {
              @Override
              public int computeHashCode(MethodSignature signature) {
                return MethodSignatureUtil.METHOD_PARAMETERS_ERASURE_EQUALITY.computeHashCode(
                    signature);
              }

              @Override
              public boolean equals(MethodSignature o1, MethodSignature o2) {
                if (!MethodSignatureUtil.METHOD_PARAMETERS_ERASURE_EQUALITY.equals(o1, o2))
                  return false;
                List<PsiMethod> list = sameParameterErasureMethods.get(o1);
                boolean toCheckReturnType = list != null && list.size() > 1;
                if (!toCheckReturnType) return true;
                PsiType returnType1 =
                    ((MethodSignatureBackedByPsiMethod) o1).getMethod().getReturnType();
                PsiType returnType2 =
                    ((MethodSignatureBackedByPsiMethod) o2).getMethod().getReturnType();
                if (returnType1 == null && returnType2 == null) return true;
                if (returnType1 == null || returnType2 == null) return false;

                PsiType erasure1 =
                    TypeConversionUtil.erasure(o1.getSubstitutor().substitute(returnType1));
                PsiType erasure2 =
                    TypeConversionUtil.erasure(o2.getSubstitutor().substitute(returnType2));
                return erasure1.equals(erasure2);
              }
            });

    for (PsiMethod method : aClass.getMethods()) {
      if (!method.isValid()) {
        throw new PsiInvalidElementAccessException(
            method, "class.valid=" + aClass.isValid() + "; name=" + method.getName());
      }
      if (!includePrivates && method.hasModifierProperty(PsiModifier.PRIVATE)) continue;
      final MethodSignatureBackedByPsiMethod signature =
          MethodSignatureBackedByPsiMethod.create(method, substitutor, isInRawContext);
      HierarchicalMethodSignatureImpl newH = new HierarchicalMethodSignatureImpl(signature);

      List<PsiMethod> list = sameParameterErasureMethods.get(signature);
      if (list == null) {
        list = new SmartList<PsiMethod>();
        sameParameterErasureMethods.put(signature, list);
      }
      list.add(method);

      LOG.assertTrue(newH.getMethod().isValid());
      result.put(signature, newH);
      map.put(signature, newH);
    }

    for (PsiClassType superType : aClass.getSuperTypes()) {
      PsiClassType.ClassResolveResult superTypeResolveResult = superType.resolveGenerics();
      PsiClass superClass = superTypeResolveResult.getElement();
      if (superClass == null) continue;
      if (!visited.add(superClass)) continue; // cyclic inheritance
      final PsiSubstitutor superSubstitutor = superTypeResolveResult.getSubstitutor();
      PsiSubstitutor finalSubstitutor =
          obtainFinalSubstitutor(superClass, superSubstitutor, substitutor, isInRawContext);

      final boolean isInRawContextSuper =
          (isInRawContext || PsiUtil.isRawSubstitutor(superClass, superSubstitutor))
              && superClass.getTypeParameters().length != 0;
      Map<MethodSignature, HierarchicalMethodSignature> superResult =
          buildMethodHierarchy(superClass, finalSubstitutor, false, visited, isInRawContextSuper);
      visited.remove(superClass);

      List<Pair<MethodSignature, HierarchicalMethodSignature>> flattened =
          new ArrayList<Pair<MethodSignature, HierarchicalMethodSignature>>();
      for (Map.Entry<MethodSignature, HierarchicalMethodSignature> entry : superResult.entrySet()) {
        HierarchicalMethodSignature hms = entry.getValue();
        MethodSignature signature = entry.getKey();
        PsiClass containingClass = hms.getMethod().getContainingClass();
        List<HierarchicalMethodSignature> supers =
            new ArrayList<HierarchicalMethodSignature>(hms.getSuperSignatures());
        for (HierarchicalMethodSignature aSuper : supers) {
          PsiClass superContainingClass = aSuper.getMethod().getContainingClass();
          if (containingClass != null
              && superContainingClass != null
              && !containingClass.isInheritor(superContainingClass, true)) {
            // methods must be inherited from unrelated classes, so flatten hierarchy here
            // class C implements SAM1, SAM2 { void methodimpl() {} }
            // hms.getSuperSignatures().remove(aSuper);
            flattened.add(
                new Pair<MethodSignature, HierarchicalMethodSignature>(signature, aSuper));
          }
        }
        putInMap(aClass, result, map, hms, signature);
      }
      for (Pair<MethodSignature, HierarchicalMethodSignature> pair : flattened) {
        putInMap(aClass, result, map, pair.second, pair.first);
      }
    }

    for (Map.Entry<MethodSignature, HierarchicalMethodSignatureImpl> entry : map.entrySet()) {
      HierarchicalMethodSignatureImpl hierarchicalMethodSignature = entry.getValue();
      MethodSignature methodSignature = entry.getKey();
      if (result.get(methodSignature) == null
          && PsiUtil.isAccessible(
              aClass.getProject(), hierarchicalMethodSignature.getMethod(), aClass, aClass)) {
        LOG.assertTrue(hierarchicalMethodSignature.getMethod().isValid());
        result.put(methodSignature, hierarchicalMethodSignature);
      }
    }

    return result;
  }