plugins/IntentionPowerPak/src/com/siyeh/ipp/types/ReplaceLambdaWithAnonymousIntention.java

/*
 * Copyright 2011 Bas Leijdekkers
 *
 * 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.siyeh.ipp.types;

import com.intellij.codeInsight.ChangeContextUtil;
import com.intellij.codeInsight.generation.GenerateMembersUtil;
import com.intellij.codeInsight.generation.OverrideImplementUtil;
import com.intellij.codeInsight.generation.PsiGenerationInfo;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.editor.Editor;
import com.intellij.psi.*;
import com.intellij.psi.codeStyle.JavaCodeStyleManager;
import com.intellij.psi.util.PsiTreeUtil;
import com.intellij.refactoring.util.RefactoringChangeUtil;
import com.intellij.util.IncorrectOperationException;
import com.intellij.util.containers.HashMap;
import com.siyeh.ipp.base.Intention;
import com.siyeh.ipp.base.PsiElementPredicate;
import org.jetbrains.annotations.NotNull;

import java.util.List;
import java.util.Map;

public class ReplaceLambdaWithAnonymousIntention extends Intention {
  private static final Logger LOG = Logger.getInstance("#" + ReplaceLambdaWithAnonymousIntention.class.getName());

  @NotNull
  @Override
  protected PsiElementPredicate getElementPredicate() {
    return new LambdaPredicate();
  }

  @Override
  protected void processIntention(@NotNull PsiElement element) throws IncorrectOperationException {
  }

  @Override
  protected void processIntention(Editor editor, @NotNull PsiElement element) throws IncorrectOperationException {
    final PsiLambdaExpression lambdaExpression = PsiTreeUtil.getParentOfType(element, PsiLambdaExpression.class);
    LOG.assertTrue(lambdaExpression != null);
    final PsiParameter[] paramListCopy = ((PsiParameterList)lambdaExpression.getParameterList().copy()).getParameters();
    final PsiType functionalInterfaceType = lambdaExpression.getFunctionalInterfaceType();
    LOG.assertTrue(functionalInterfaceType != null);
    final PsiMethod method = LambdaUtil.getFunctionalInterfaceMethod(functionalInterfaceType);
    LOG.assertTrue(method != null);

    final String blockText = getBodyText(lambdaExpression);
    if (blockText == null) return;

    final PsiElementFactory psiElementFactory = JavaPsiFacade.getElementFactory(element.getProject());
    PsiCodeBlock blockFromText = psiElementFactory.createCodeBlockFromText(blockText, lambdaExpression);
    ChangeContextUtil.encodeContextInfo(blockFromText, true);
    PsiNewExpression newExpression = (PsiNewExpression)psiElementFactory.createExpressionFromText("new " + functionalInterfaceType.getCanonicalText() + "(){}", lambdaExpression);
    final PsiClass thisClass = RefactoringChangeUtil.getThisClass(lambdaExpression);
    final String thisClassName = thisClass != null ? thisClass.getName() : null;
    if (thisClassName != null) {
      final PsiThisExpression thisAccessExpr = thisClass instanceof PsiAnonymousClass ? null : RefactoringChangeUtil
        .createThisExpression(lambdaExpression.getManager(), thisClass);
      ChangeContextUtil.decodeContextInfo(blockFromText, thisClass, thisAccessExpr);
      final Map<PsiElement, PsiElement> replacements = new HashMap<PsiElement, PsiElement>();
      blockFromText.accept(new JavaRecursiveElementWalkingVisitor() {
        @Override
        public void visitClass(PsiClass aClass) {}

        @Override
        public void visitSuperExpression(PsiSuperExpression expression) {
          super.visitSuperExpression(expression);
          if (expression.getQualifier() == null) {
            replacements.put(expression, psiElementFactory.createExpressionFromText(thisClassName + "." + expression.getText(), expression));
          }
        }

        @Override
        public void visitMethodCallExpression(PsiMethodCallExpression expression) {
          super.visitMethodCallExpression(expression);
          if (thisAccessExpr != null) {
            final PsiMethod psiMethod = expression.resolveMethod();
            if (psiMethod != null && !psiMethod.hasModifierProperty(PsiModifier.STATIC) && expression.getMethodExpression().getQualifierExpression() == null) {
              replacements.put(expression, psiElementFactory.createExpressionFromText(thisAccessExpr.getText() + "." + expression.getText(), expression));
            }
          }
        }
      });
      for (PsiElement psiElement : replacements.keySet()) {
        psiElement.replace(replacements.get(psiElement));
      }
    }
    blockFromText = psiElementFactory.createCodeBlockFromText(blockFromText.getText(), null);
    newExpression = (PsiNewExpression)JavaCodeStyleManager.getInstance(lambdaExpression.getProject()).shortenClassReferences(lambdaExpression.replace(newExpression));

    final PsiAnonymousClass anonymousClass = newExpression.getAnonymousClass();
    LOG.assertTrue(anonymousClass != null);
    final List<PsiGenerationInfo<PsiMethod>> infos = OverrideImplementUtil.overrideOrImplement(anonymousClass, method);
    if (infos != null && infos.size() == 1) {
      final PsiMethod member = infos.get(0).getPsiMember();
      final PsiParameter[] parameters = member.getParameterList().getParameters();
      for (int i = 0; i < parameters.length; i++) {
        final PsiParameter parameter = parameters[i];
        final String lambdaParamName = paramListCopy[i].getName();
        if (lambdaParamName != null) {
          parameter.setName(lambdaParamName);
        }
      }
      PsiCodeBlock codeBlock = member.getBody();
      LOG.assertTrue(codeBlock != null);

      codeBlock = (PsiCodeBlock)codeBlock.replace(blockFromText);
      GenerateMembersUtil.positionCaret(editor, member, true);
    }
  }

  private static String getBodyText(PsiLambdaExpression lambdaExpression) {
    String blockText;
    final PsiElement body = lambdaExpression.getBody();
    if (body instanceof PsiExpression) {
      blockText = "{";
      blockText += ((PsiExpression)body).getType() == PsiType.VOID ? "" : "return ";
      blockText +=  body.getText() + ";}";
    } else if (body != null) {
      blockText = body.getText();
    } else {
      blockText = null;
    }
    return blockText;
  }

  private static class LambdaPredicate implements PsiElementPredicate {
    @Override
    public boolean satisfiedBy(PsiElement element) {
      final PsiLambdaExpression lambdaExpression = PsiTreeUtil.getParentOfType(element, PsiLambdaExpression.class);
      if (lambdaExpression != null && (element.getParent() == lambdaExpression && element instanceof PsiJavaToken && ((PsiJavaToken)element).getTokenType() == JavaTokenType.ARROW || 
                                       PsiTreeUtil.isAncestor(lambdaExpression.getParameterList(), element, false))) {
        final PsiClass thisClass = PsiTreeUtil.getParentOfType(lambdaExpression, PsiClass.class, true);
        if (thisClass == null || thisClass instanceof PsiAnonymousClass) {
          final PsiElement body = lambdaExpression.getBody();
          if (body == null) return false;
          final boolean [] disabled = new boolean[1];
          body.accept(new JavaRecursiveElementWalkingVisitor() {
            @Override
            public void visitThisExpression(PsiThisExpression expression) {
              disabled[0] = true;
            }

            @Override
            public void visitSuperExpression(PsiSuperExpression expression) {
              disabled[0] = true;
            }
          });
          if (disabled[0]) return false;
        }
        final PsiType functionalInterfaceType = lambdaExpression.getFunctionalInterfaceType();
        return functionalInterfaceType != null &&
               LambdaUtil.getFunctionalInterfaceMethod(functionalInterfaceType) != null &&
               LambdaUtil.isLambdaFullyInferred(lambdaExpression, functionalInterfaceType) &&
               LambdaUtil.isFunctionalType(functionalInterfaceType);
      }
      return false;
    }
  }
}