ExtractClassHandler.java

/*
 * Copyright 2000-2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.refactoring.extractclass;

import com.intellij.lang.ContextAwareActionHandler;
import com.intellij.openapi.actionSystem.DataContext;
import com.intellij.openapi.editor.CaretModel;
import com.intellij.openapi.editor.Editor;
import com.intellij.openapi.editor.ScrollType;
import com.intellij.openapi.editor.ScrollingModel;
import com.intellij.openapi.project.Project;
import com.intellij.psi.*;
import com.intellij.psi.util.PsiTreeUtil;
import com.intellij.psi.util.PsiUtil;
import com.intellij.refactoring.HelpID;
import com.intellij.refactoring.RefactorJBundle;
import com.intellij.refactoring.lang.ElementsHandler;
import com.intellij.refactoring.util.CommonRefactoringUtil;
import org.jetbrains.annotations.NotNull;

public class ExtractClassHandler implements ElementsHandler, ContextAwareActionHandler {
  protected static String getHelpID() {
    return HelpID.ExtractClass;
  }

  @Override
  public boolean isAvailableForQuickList(@NotNull Editor editor, @NotNull PsiFile file, @NotNull DataContext dataContext) {
    return !PsiUtil.isModuleFile(file);
  }

  @Override
  public boolean isEnabledOnElements(PsiElement[] elements) {
    return elements.length == 1 && PsiTreeUtil.getParentOfType(elements[0], PsiClass.class, false) != null;
  }

  public void invoke(@NotNull Project project, Editor editor, PsiFile file, DataContext dataContext) {
    final ScrollingModel scrollingModel = editor.getScrollingModel();
    scrollingModel.scrollToCaret(ScrollType.MAKE_VISIBLE);
    final CaretModel caretModel = editor.getCaretModel();
    final int position = caretModel.getOffset();
    final PsiElement element = file.findElementAt(position);

    final PsiMember selectedMember = PsiTreeUtil.getParentOfType(element, PsiMember.class, true);
    if (selectedMember == null) {
      //todo
      return;
    }
    
    PsiClass containingClass = selectedMember.getContainingClass();

    if (containingClass == null && selectedMember instanceof PsiClass) {
      containingClass = (PsiClass)selectedMember;
    }

    final String cannotRefactorMessage = getCannotRefactorMessage(containingClass);
    if (cannotRefactorMessage != null)  {
      CommonRefactoringUtil.showErrorHint(project, editor, 
                                          RefactorJBundle.message("cannot.perform.the.refactoring") + cannotRefactorMessage, 
                                          ExtractClassProcessor.REFACTORING_NAME, getHelpID());
      return;
    }
    new ExtractClassDialog(containingClass, selectedMember).show();
  }

  private static String getCannotRefactorMessage(PsiClass containingClass) {
    if (containingClass == null) {
      return RefactorJBundle.message("the.caret.should.be.positioned.within.a.class.to.be.refactored");
    }
    if (containingClass.isInterface()) {
      return RefactorJBundle.message("the.selected.class.is.an.interface");
    }
    if (containingClass.isEnum()) {
      return RefactorJBundle.message("the.selected.class.is.an.enumeration");
    }
    if (containingClass.isAnnotationType()) {
      return RefactorJBundle.message("the.selected.class.is.an.annotation.type");
    }
    if (classIsInner(containingClass) && !containingClass.hasModifierProperty(PsiModifier.STATIC)) {
      return RefactorJBundle.message("the.refactoring.is.not.supported.on.non.static.inner.classes");
    }
    if (classIsTrivial(containingClass)) {
      return RefactorJBundle.message("the.selected.class.has.no.members.to.extract");
    }
    if (!containingClass.getManager().isInProject(containingClass)) {
      return "The selected class should belong to project sources";
    }
    return null;
  }

  private static boolean classIsInner(PsiClass aClass) {
    return PsiTreeUtil.getParentOfType(aClass, PsiClass.class, true) != null;
  }

  public void invoke(@NotNull Project project, @NotNull PsiElement[] elements, DataContext dataContext) {
    if (elements.length != 1) {
      return;
    }
    final PsiClass containingClass = PsiTreeUtil.getParentOfType(elements[0], PsiClass.class, false);

    final PsiMember selectedMember = PsiTreeUtil.getParentOfType(elements[0], PsiMember.class, false);
    if (containingClass == null) {
      return;
    }
    if (classIsTrivial(containingClass)) {
      return;
    }
    new ExtractClassDialog(containingClass, selectedMember).show();
  }

  private static boolean classIsTrivial(PsiClass containingClass) {
    if (containingClass.getFields().length == 0) {
      final PsiMethod[] methods = containingClass.getMethods();
      if (methods.length == 0) return true;
      for (PsiMethod method : methods) {
        if (method.getBody() != null) return false;
      }
      return true;
    }
    return false;
  }
}