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/*
 * SonarQube Java
 * Copyright (C) 2012 SonarSource
 * [email protected]
 *
 * 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  02
 */
package org.sonar.java.checks;

import com.google.common.collect.HashBasedTable;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Table;
import org.apache.commons.lang.BooleanUtils;
import org.sonar.api.server.rule.RulesDefinition;
import org.sonar.check.Priority;
import org.sonar.check.Rule;
import org.sonar.java.syntaxtoken.FirstSyntaxTokenFinder;
import org.sonar.java.tag.Tag;
import org.sonar.plugins.java.api.JavaFileScanner;
import org.sonar.plugins.java.api.JavaFileScannerContext;
import org.sonar.plugins.java.api.tree.AnnotationTree;
import org.sonar.plugins.java.api.tree.ArrayAccessExpressionTree;
import org.sonar.plugins.java.api.tree.AssignmentExpressionTree;
import org.sonar.plugins.java.api.tree.BaseTreeVisitor;
import org.sonar.plugins.java.api.tree.BinaryExpressionTree;
import org.sonar.plugins.java.api.tree.ConditionalExpressionTree;
import org.sonar.plugins.java.api.tree.ExpressionTree;
import org.sonar.plugins.java.api.tree.IfStatementTree;
import org.sonar.plugins.java.api.tree.LiteralTree;
import org.sonar.plugins.java.api.tree.MethodInvocationTree;
import org.sonar.plugins.java.api.tree.NewArrayTree;
import org.sonar.plugins.java.api.tree.NewClassTree;
import org.sonar.plugins.java.api.tree.ParenthesizedTree;
import org.sonar.plugins.java.api.tree.Tree;
import org.sonar.plugins.java.api.tree.UnaryExpressionTree;
import org.sonar.squidbridge.annotations.SqaleConstantRemediation;
import org.sonar.squidbridge.annotations.SqaleSubCharacteristic;

import java.util.Deque;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Set;

@Rule(
  key = "S864",
  name = "Limited dependence should be placed on operator precedence rules in expressions",
  priority = Priority.MAJOR,
  tags = {Tag.CERT, Tag.CWE, Tag.MISRA})
@SqaleSubCharacteristic(RulesDefinition.SubCharacteristics.READABILITY)
@SqaleConstantRemediation("2min")
public class OperatorPrecedenceCheck extends BaseTreeVisitor implements JavaFileScanner {

  private static final Table OPERATORS_RELATION_TABLE;

  private static final Set ARITHMETIC_OPERATORS = ImmutableSet.of(
    Tree.Kind.MINUS,
    Tree.Kind.REMAINDER,
    Tree.Kind.MULTIPLY,
    Tree.Kind.PLUS
    );

  private static final Set EQUALITY_RELATIONAL_OPERATORS = ImmutableSet.of(
    Tree.Kind.EQUAL_TO,
    Tree.Kind.GREATER_THAN,
    Tree.Kind.GREATER_THAN_OR_EQUAL_TO,
    Tree.Kind.LESS_THAN,
    Tree.Kind.LESS_THAN_OR_EQUAL_TO,
    Tree.Kind.NOT_EQUAL_TO
    );

  private static final Set SHIFT_OPERATORS = ImmutableSet.of(
    Tree.Kind.LEFT_SHIFT,
    Tree.Kind.RIGHT_SHIFT,
    Tree.Kind.UNSIGNED_RIGHT_SHIFT
    );

  private static final Tree.Kind[] CONDITIONAL_EXCLUSIONS = new Tree.Kind[]{
      Tree.Kind.METHOD_INVOCATION, Tree.Kind.IDENTIFIER, Tree.Kind.MEMBER_SELECT,
      Tree.Kind.PARENTHESIZED_EXPRESSION, Tree.Kind.TYPE_CAST, Tree.Kind.NEW_CLASS,
      Tree.Kind.ARRAY_ACCESS_EXPRESSION
  };

  private static void put(Iterable firstSet, Iterable secondSet) {
    for (Tree.Kind first : firstSet) {
      for (Tree.Kind second : secondSet) {
        OPERATORS_RELATION_TABLE.put(first, second, true);
      }
    }
  }

  static {
    OPERATORS_RELATION_TABLE = HashBasedTable.create();
    put(ARITHMETIC_OPERATORS, Iterables.concat(SHIFT_OPERATORS, ImmutableSet.of(Tree.Kind.AND, Tree.Kind.XOR, Tree.Kind.OR)));
    put(SHIFT_OPERATORS, Iterables.concat(ARITHMETIC_OPERATORS, ImmutableSet.of(Tree.Kind.AND, Tree.Kind.XOR, Tree.Kind.OR)));
    put(ImmutableSet.of(Tree.Kind.AND), Iterables.concat(ARITHMETIC_OPERATORS, SHIFT_OPERATORS, ImmutableSet.of(Tree.Kind.XOR, Tree.Kind.OR)));
    put(ImmutableSet.of(Tree.Kind.XOR), Iterables.concat(ARITHMETIC_OPERATORS, SHIFT_OPERATORS, ImmutableSet.of(Tree.Kind.AND, Tree.Kind.OR)));
    put(ImmutableSet.of(Tree.Kind.OR), Iterables.concat(ARITHMETIC_OPERATORS, SHIFT_OPERATORS, ImmutableSet.of(Tree.Kind.AND, Tree.Kind.XOR)));
    put(ImmutableSet.of(Tree.Kind.CONDITIONAL_AND), ImmutableSet.of(Tree.Kind.CONDITIONAL_OR));
    put(ImmutableSet.of(Tree.Kind.CONDITIONAL_OR), ImmutableSet.of(Tree.Kind.CONDITIONAL_AND));
  }

  private JavaFileScannerContext context;
  private Deque stack = new LinkedList<>();
  private Set reportedLines = new HashSet<>();

  @Override
  public void scanFile(JavaFileScannerContext context) {
    this.context = context;
    reportedLines.clear();
    scan(context.getTree());
    reportedLines.clear();
  }

  @Override
  public void visitAnnotation(AnnotationTree tree) {
    stack.push(null);
    for (ExpressionTree argument : tree.arguments()) {
      if (argument.is(Tree.Kind.ASSIGNMENT)) {
        scan(((AssignmentExpressionTree) argument).expression());
      } else {
        scan(argument);
      }
    }
    stack.pop();
  }

  @Override
  public void visitArrayAccessExpression(ArrayAccessExpressionTree tree) {
    scan(tree.expression());
    stack.push(null);
    scan(tree.dimension());
    stack.pop();
  }

  @Override
  public void visitBinaryExpression(BinaryExpressionTree tree) {
    Tree.Kind peek = stack.peek();
    Tree.Kind kind = tree.kind();
    if (requiresParenthesis(peek, kind)) {
      raiseIssue(tree.operatorToken().line(), tree);
    }
    stack.push(kind);
    super.visitBinaryExpression(tree);
    stack.pop();
  }

  private static boolean requiresParenthesis(Tree.Kind kind1, Tree.Kind kind2) {
    return BooleanUtils.isTrue(OPERATORS_RELATION_TABLE.get(kind1, kind2));
  }

  @Override
  public void visitIfStatement(IfStatementTree tree) {
    super.visitIfStatement(tree);
    ExpressionTree condition = tree.condition();
    if (condition.is(Tree.Kind.ASSIGNMENT) && EQUALITY_RELATIONAL_OPERATORS.contains(((AssignmentExpressionTree) condition).expression().kind())) {
      raiseIssue(((AssignmentExpressionTree) condition).operatorToken().line(), tree);
    }
  }

  @Override
  public void visitMethodInvocation(MethodInvocationTree tree) {
    scan(tree.methodSelect());
    scan(tree.typeArguments());
    for (ExpressionTree argument : tree.arguments()) {
      stack.push(null);
      scan(argument);
      stack.pop();
    }
  }

  @Override
  public void visitNewArray(NewArrayTree tree) {
    stack.push(null);
    super.visitNewArray(tree);
    stack.pop();
  }

  @Override
  public void visitNewClass(NewClassTree tree) {
    stack.push(null);
    super.visitNewClass(tree);
    stack.pop();
  }

  @Override
  public void visitParenthesized(ParenthesizedTree tree) {
    stack.push(null);
    super.visitParenthesized(tree);
    stack.pop();
  }

  @Override
  public void visitConditionalExpression(ConditionalExpressionTree tree) {
    checkConditionalOperand(tree.trueExpression());
    checkConditionalOperand(tree.falseExpression());
    super.visitConditionalExpression(tree);
  }

  private void checkConditionalOperand(ExpressionTree tree) {
    if(!(tree.is(CONDITIONAL_EXCLUSIONS) || tree instanceof LiteralTree || tree instanceof UnaryExpressionTree)) {
      raiseIssue(FirstSyntaxTokenFinder.firstSyntaxToken(tree).line(), tree);
    }
  }

  private void raiseIssue(int line, Tree tree) {
    if (reportedLines.add(line)) {
      context.addIssue(tree, this, "Add parentheses to make the operator precedence explicit.");
    }
  }

}