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/*
 * SonarQube JavaScript Plugin
 * Copyright (C) 2011-2018 SonarSource SA
 * mailto:info 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.javascript.se.points;

import java.util.Optional;
import org.sonar.javascript.se.Constraint;
import org.sonar.javascript.se.ExpressionStack;
import org.sonar.javascript.se.ProgramState;
import org.sonar.javascript.se.SymbolicExecution;
import org.sonar.javascript.se.sv.IncDecSymbolicValue;
import org.sonar.javascript.se.sv.IncDecSymbolicValue.Sign;
import org.sonar.javascript.se.sv.SymbolicValue;
import org.sonar.javascript.se.sv.SymbolicValueWithConstraint;
import org.sonar.javascript.se.sv.UnaryMinusSymbolicValue;
import org.sonar.javascript.tree.KindSet;
import org.sonar.plugins.javascript.api.symbols.Symbol;
import org.sonar.plugins.javascript.api.tree.Tree;
import org.sonar.plugins.javascript.api.tree.Tree.Kind;
import org.sonar.plugins.javascript.api.tree.expression.UnaryExpressionTree;

public class UnaryNumericProgramPoint implements ProgramPoint {
  private UnaryExpressionTree element;
  private SymbolicExecution execution;

  private SymbolicValue expressionValue;
  private SymbolicValue assignedValue = null;

  public UnaryNumericProgramPoint(Tree element, SymbolicExecution execution) {
    this.element = (UnaryExpressionTree) element;
    this.execution = execution;
  }

  @Override
  public Optional execute(ProgramState state) {
    ExpressionStack stack = state.getStack();

    ExpressionStack stackAfterExecution = stack.apply(newStack -> {
      SymbolicValue operandValue = newStack.pop();
      Constraint operandConstraint = state.getConstraint(operandValue);

      execute(operandValue, operandConstraint);
      newStack.push(expressionValue);
    });


    ProgramState newPS = state.withStack(stackAfterExecution);
    newPS = executeAssignment(newPS);

    return Optional.of(newPS);
  }

  private void execute(SymbolicValue operandValue, Constraint operandConstraint) {
    if (element.is(Kind.PREFIX_INCREMENT, Kind.PREFIX_DECREMENT)) {
      Sign sign = element.is(Kind.PREFIX_INCREMENT) ? Sign.PLUS : Sign.MINUS;
      this.expressionValue = new IncDecSymbolicValue(sign, operandValue);
      this.assignedValue = this.expressionValue;
    }

    if (element.is(Kind.POSTFIX_INCREMENT, Kind.POSTFIX_DECREMENT)) {
      Sign sign = element.is(Kind.POSTFIX_INCREMENT) ? Sign.PLUS : Sign.MINUS;

      this.expressionValue = convertToNumber(operandValue, operandConstraint);
      this.assignedValue = new IncDecSymbolicValue(sign, operandValue);
    }

    if (element.is(Kind.UNARY_MINUS, Kind.UNARY_PLUS)) {
      this.assignedValue = null;

      if (element.is(Kind.UNARY_PLUS)) {
        this.expressionValue = convertToNumber(operandValue, operandConstraint);

      } else {
        this.expressionValue = new UnaryMinusSymbolicValue(operandValue);

      }
    }
  }

  private SymbolicValue convertToNumber(SymbolicValue operandValue, Constraint operandConstraint) {
    boolean requiresConversionToNumber = !operandConstraint.isStricterOrEqualTo(Constraint.NUMBER_PRIMITIVE);
    return requiresConversionToNumber ? new SymbolicValueWithConstraint(Constraint.NUMBER_PRIMITIVE) : operandValue;
  }

  private ProgramState executeAssignment(ProgramState state) {
    ProgramState newPS = state;

    if (assignedValue != null) {
      Symbol symbol = execution.trackedVariable(element.expression());
      if (symbol != null) {
        newPS = newPS.assignment(symbol, assignedValue);
      }
    }

    return newPS;
  }

  public static boolean originatesFrom(Tree element) {
    return element.is(
      Kind.UNARY_PLUS,
      Kind.UNARY_MINUS,
      KindSet.INC_DEC_KINDS);
  }
}