/* PIA - Lenguajes Modernos de Programación
 * FACULTAD DE CIENCIAS FÍSICO MATEMÁTICAS
 * Luis Sebastián Martínez Vega - LCC */

#include "include/simplifier.hpp"
#include "include/expressions.hpp"
#include <cstddef>

void Simplifier::simplifyChildren(Expression *root, Expression *left, Expression *right) {
  left = root->getLeft()->simplify(root->getLeft(), this);
  right = root->getRight()->simplify(root->getRight(), this);
}

// Reglas de simplificación.
Expression *Simplifier::ruleEval(Expression *expr) {
  Literal *left = dynamic_cast <Literal *>(expr->getLeft());
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if(left != NULL && right != NULL) 
    return new Literal(expr->eval());

  return NULL;
}

Expression *Simplifier::ruleMultiplyByOne(MultiplicationExpression *expr) {
  Literal *left = dynamic_cast <Literal *>(expr->getLeft());
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if(left != NULL && left->getValue() == 1)
    return expr->getRight()->copy();

  if(right != NULL && right->getValue() == 1)
    return expr->getLeft()->copy();

  return NULL;
}

Expression *Simplifier::ruleDivideByOne(DivisionExpression *expr) {
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if (right != NULL && right->getValue() == 1)
    return expr->getLeft()->copy();

  return NULL;
}

Expression *Simplifier::ruleMultiplyByZero(MultiplicationExpression *expr) {
  Literal *left = dynamic_cast <Literal *>(expr->getLeft());
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if((left != NULL && left->getValue() == 0) || (right != NULL && right->getValue() == 0))
    return new Literal(0);

  return NULL;
}

Expression *Simplifier::ruleZeroDivision(DivisionExpression *expr) {
  Literal *left = dynamic_cast <Literal *>(expr->getLeft());

  if(left != NULL && left->getValue() == 0)
    return new Literal(0);

  return NULL;
}

Expression *Simplifier::ruleOnePower(PowerExpression *expr) {
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if(right != NULL && right->getValue() == 1)
    return expr->getLeft()->copy();

  return NULL;
}

Expression *Simplifier::ruleZeroPower(PowerExpression *expr) {
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if(right != NULL && right->getValue() == 0)
    return new Literal(1);

  return NULL;
}

Expression *Simplifier::addZero(AddExpression *expr) {
  Literal *left = dynamic_cast <Literal *>(expr->getLeft());
  Literal *right = dynamic_cast <Literal *>(expr->getRight());

  if(left != NULL && left->getValue() == 0)
    return expr->getRight()->copy();

  if(right != NULL && right->getValue() == 0)
    return expr->getLeft()->copy();

  return NULL;
}