package calculator.operations;
   
   import java.util.List;
   
   import calculator.Expression;
   import calculator.IllegalConstruction;
   import calculator.atoms.Complex;
   import calculator.atoms.IntegerAtom;
   import calculator.atoms.Rationnal;
  import calculator.atoms.Real;
  
  /**
   * This class represents the arithmetic multiplication operation "*".
   * The class extends an abstract superclass Operation.
   * Other subclasses of Operation represent other arithmetic operations.
   * 
   * @see Operation
   * @see Minus
   * @see Plus
   * @see Divides
   */
  public final class Times extends Operation {
  	/**
  	 * Class constructor specifying a number of Expressions to multiply.
  	 *
  	 * @param elist The list of Expressions to multiply
  	 * @throws IllegalConstruction If an empty list of expressions if passed as
  	 *                             parameter
  	 * @see #Times(List<Expression>)
  	 */
  	public Times(List<Expression> elist) throws IllegalConstruction {
  		super(elist);
  		symbol = "*";
  		neutral = 1;
  	}
  
  	/**
  	 * The actual computation of the (binary) arithmetic multiplication of two Reals
  	 * 
  	 * @param r1 The first Real
  	 * @param r2 The second Real
  	 * @return The (new) Real that is the result of the multiplication
  	 */
  	public Real op(Real r1, Real r2) {
  
  		if (r1.isNan() || r2.isNan()) // NaN * x = NaN
  			return Real.nan();
  
  		// case of inf * 0 = NaN
  		if (r1.getValue().doubleValue() == 0 && (r2.isPlusInf() || r2.isMinusInf()))
  			return Real.nan();
  
  		if (r2.getValue().doubleValue() == 0 && (r1.isPlusInf() || r1.isMinusInf()))
  			return Real.nan();
  
  		if (r1.isPlusInf() || r1.isMinusInf() || r2.isPlusInf() || r2.isMinusInf()) { // inf/x = +/- inf
  			// int whose sign is the resulting sign of the infinity
  			Double sign = r1.getValue().doubleValue() * r2.getValue().doubleValue();
  			if (sign > 0)
  				return Real.plusInf();
  			else
  				return Real.minusInf();
  		}
  		return new Real(r1.getValue().multiply(r2.getValue()));
  	}
  
  	/**
  	 * The actual computation of the (binary) arithmetic multiplication of two
  	 * Integers
  	 * 
  	 * @param i1 The first IntegerAtom
  	 * @param i2 The second IntegerAtom
  	 * @return The (new) IntegerAtom that is the result of the multiplication
  	 */
  	public IntegerAtom op(IntegerAtom i1, IntegerAtom i2) {
  		return new IntegerAtom(i1.getValue() * i2.getValue());
  	}
  
  	@Override
  	public Complex op(Complex c1, Complex c2) {
  		if (c1.isNaN() || c2.isNaN()) {
  			return Complex.nan();
  		}
  		org.apache.commons.numbers.complex.Complex result = c1.getValue().multiply(c2.getValue());
  		return new Complex(result);
  	}
  
  	@Override
  	public Rationnal op(Rationnal q1, Rationnal q2) {
  		org.apache.commons.numbers.fraction.Fraction result = q1.getValue().multiply(q2.getValue());
  		return new Rationnal(result);
  	}
  }