/*
 * 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.slicer;

import com.intellij.codeInsight.PsiEquivalenceUtil;
import com.intellij.openapi.application.ReadAction;
import com.intellij.openapi.util.Comparing;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiNamedElement;
import com.intellij.psi.impl.source.tree.AstBufferUtil;
import gnu.trove.TObjectHashingStrategy;
import org.jetbrains.annotations.NotNull;

public class SliceLeafEquality implements TObjectHashingStrategy<PsiElement> {
  @NotNull
  protected PsiElement substituteElement(@NotNull PsiElement element) {
    return element;
  }

  @Override
  public int computeHashCode(final PsiElement element) {
    if (element == null) return 0;
    String text = ReadAction.compute(() -> {
      PsiElement elementToCompare = substituteElement(element);
      return elementToCompare instanceof PsiNamedElement ? ((PsiNamedElement)elementToCompare).getName()
                                                         : AstBufferUtil.getTextSkippingWhitespaceComments(elementToCompare.getNode());
    });
    return Comparing.hashcode(text);
  }

  @Override
  public boolean equals(final PsiElement o1, final PsiElement o2) {
    return ReadAction
      .compute(() -> o1 != null && o2 != null && PsiEquivalenceUtil.areElementsEquivalent(o1, o2));
  }
}
