/*
 * SonarQube Java
 * Copyright (C) 2012-2016 SonarSource SA
 * mailto:contact AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.java.checks;

import com.google.common.collect.ImmutableList;
import org.sonar.check.Rule;
import org.sonar.java.matcher.MethodMatcher;
import org.sonar.java.model.ModifiersUtils;
import org.sonar.plugins.java.api.semantic.Symbol;
import org.sonar.plugins.java.api.tree.ArrayAccessExpressionTree;
import org.sonar.plugins.java.api.tree.AssignmentExpressionTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.IdentifierTree;
import org.sonar.plugins.java.api.tree.MemberSelectExpressionTree;
import org.sonar.plugins.java.api.tree.MethodTree;
import org.sonar.plugins.java.api.tree.Modifier;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.Tree.Kind;
import org.sonar.plugins.java.api.tree.UnaryExpressionTree;

import java.util.Deque;
import java.util.LinkedList;
import java.util.List;

@Rule(key = "S2696")
public class StaticFieldUpateCheck extends AbstractInSynchronizeChecker {

  private static final Kind[] ASSIGNMENT_EXPRESSIONS = new Kind[]{
    Kind.AND_ASSIGNMENT,
    Kind.ASSIGNMENT,
    Kind.DIVIDE_ASSIGNMENT,
    Kind.LEFT_SHIFT_ASSIGNMENT,
    Kind.MINUS_ASSIGNMENT,
    Kind.MULTIPLY_ASSIGNMENT,
    Kind.OR_ASSIGNMENT,
    Kind.PLUS_ASSIGNMENT,
    Kind.REMAINDER_ASSIGNMENT,
    Kind.UNSIGNED_RIGHT_SHIFT_ASSIGNMENT,
    Kind.XOR_ASSIGNMENT};

  private static final Kind[] UNARY_EXPRESSIONS = new Kind[]{
    Kind.POSTFIX_DECREMENT,
    Kind.POSTFIX_INCREMENT,
    Kind.PREFIX_DECREMENT,
    Kind.PREFIX_INCREMENT};

  private Deque<Boolean> withinStaticMethod = new LinkedList<>();

  @Override
  public List<Kind> nodesToVisit() {
    ImmutableList.Builder<Kind> builder = ImmutableList.builder();
    builder.addAll(super.nodesToVisit());
    builder.add(Kind.STATIC_INITIALIZER);
    builder.add(ASSIGNMENT_EXPRESSIONS);
    builder.add(UNARY_EXPRESSIONS);
    return builder.build();
  }

  @Override
  public void visitNode(Tree tree) {
    // use AbstractInSynchronizeChecker logic to check synchronized blocks
    super.visitNode(tree);

    if (tree.is(Kind.METHOD)) {
      withinStaticMethod.push(isMethodStatic((MethodTree) tree));
    } else if (tree.is(Kind.STATIC_INITIALIZER)) {
      withinStaticMethod.push(true);
    } else if (hasSemantic() && isInInstanceMethod() && !hasAnyParentStatic() && !hasAnyParentSync()) {
      if (tree.is(ASSIGNMENT_EXPRESSIONS)) {
        checkVariableModification(((AssignmentExpressionTree) tree).variable());
      } else if (tree.is(UNARY_EXPRESSIONS)) {
        checkVariableModification(((UnaryExpressionTree) tree).expression());
      }
    }
  }

  private boolean hasAnyParentStatic() {
    return withinStaticMethod.contains(true);
  }

  private boolean isInInstanceMethod() {
    return !withinStaticMethod.isEmpty() && !withinStaticMethod.peek();
  }

  private static boolean isMethodStatic(MethodTree tree) {
    return ModifiersUtils.hasModifier(tree.modifiers(), Modifier.STATIC);
  }

  @Override
  public void leaveNode(Tree tree) {
    // use AbstractInSynchronizeChecker logic to keep updated synchronized blocks tracking
    super.leaveNode(tree);

    if (tree.is(Tree.Kind.METHOD, Kind.STATIC_INITIALIZER)) {
      withinStaticMethod.pop();
    }
  }

  private void checkVariableModification(ExpressionTree expression) {
    if (expression.is(Kind.IDENTIFIER)) {
      checkFieldModification((IdentifierTree) expression);
    } else if (expression.is(Kind.MEMBER_SELECT)) {
      checkFieldModification(((MemberSelectExpressionTree) expression).identifier());
    } else if (expression.is(Kind.ARRAY_ACCESS_EXPRESSION)) {
      checkVariableModification(((ArrayAccessExpressionTree) expression).expression());
    }
  }

  private void checkFieldModification(IdentifierTree identifier) {
    Symbol variable = identifier.symbol();
    if (isStaticField(variable)) {
      reportIssue(identifier, "Make the enclosing method \"static\" or remove this set.");
    }
  }

  private static boolean isStaticField(Symbol symbol) {
    return symbol.isVariableSymbol()
      && symbol.owner().isTypeSymbol()
      && symbol.isStatic();
  }

  @Override
  protected List<MethodMatcher> getMethodInvocationMatchers() {
    return ImmutableList.of();
  }
}