package fr.umlv.calc;

import static java.util.Objects.requireNonNull;

public record OpOrValue(int operator, int value, OpOrValue left, OpOrValue right) {
  public static final int OP_NONE = 0;
  public static final int OP_ADD = 1;
  public static final int OP_SUB = 2;

  public OpOrValue(int value) {
    this(OP_NONE, value, null, null);
  }
  public OpOrValue(int operator, OpOrValue left, OpOrValue right) {
    this(operator, 0, left, right);
    requireNonNull(left);
    requireNonNull(right);
    if (operator != OP_ADD && operator != OP_SUB) {
      throw new IllegalArgumentException("bad operator");
    }
  }

  public int eval() {
    return switch (operator) {
      case OP_ADD -> left.eval() + right.eval();
      case OP_SUB -> left.eval() - right.eval();
      // case OP_NONE:
      default -> value;
    };
  }

  public static void main(String[] args) {
    OpOrValue expression = new OpOrValue(OP_ADD,
        new OpOrValue(2),
        new OpOrValue(3)
    );
    System.out.println(expression.eval());
  }
}