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/*
 * Copyright 2003-2011 Dave Griffith, 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.ig.numeric;

import com.intellij.psi.*;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.util.ConstantExpressionUtil;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import org.jetbrains.annotations.NotNull;

public class DivideByZeroInspection extends BaseInspection {

  @NotNull
  public String getID() {
    return "divzero";
  }

  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message("divide.by.zero.display.name");
  }

  @NotNull
  protected String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message(
      "divide.by.zero.problem.descriptor");
  }

  public BaseInspectionVisitor buildVisitor() {
    return new DivisionByZeroVisitor();
  }

  private static class DivisionByZeroVisitor extends BaseInspectionVisitor {

    @Override
    public void visitBinaryExpression(
      @NotNull PsiBinaryExpression expression) {
      super.visitBinaryExpression(expression);
      final PsiExpression rhs = expression.getROperand();
      if (rhs == null) {
        return;
      }
      final IElementType tokenType = expression.getOperationTokenType();
      if (!tokenType.equals(JavaTokenType.DIV) &&
          !tokenType.equals(JavaTokenType.PERC)) {
        return;
      }
      final Object value =
        ConstantExpressionUtil.computeCastTo(rhs, PsiType.DOUBLE);
      if (!(value instanceof Double)) {
        return;
      }
      final double constantValue = ((Double)value).doubleValue();
      if (constantValue == 0.0 || constantValue == -0.0) {
        registerError(expression);
      }
    }

    @Override
    public void visitAssignmentExpression(
      PsiAssignmentExpression expression) {
      super.visitAssignmentExpression(expression);
      final PsiExpression rhs = expression.getRExpression();
      if (rhs == null) {
        return;
      }
      final IElementType tokenType = expression.getOperationTokenType();
      if (!tokenType.equals(JavaTokenType.DIVEQ)
          && !tokenType.equals(JavaTokenType.PERCEQ)) {
        return;
      }
      final Object value = ConstantExpressionUtil.computeCastTo(rhs,
                                                                PsiType.DOUBLE);
      if (!(value instanceof Double)) {
        return;
      }
      final double constantValue = ((Double)value).doubleValue();
      if (constantValue == 0.0 || constantValue == -0.0) {
        registerError(expression);
      }
    }
  }
}