package calculator.functions;
   
   import java.math.BigDecimal;
   
   import calculator.Expression;
   import calculator.IllegalConstruction;
   import calculator.atoms.Complex;
   import calculator.atoms.IntegerAtom;
   import calculator.atoms.Rationnal;
  import calculator.atoms.Real;
  import ch.obermuhlner.math.big.BigDecimalMath;
  
  /**
   * This class represents the arithmetic unary operation "atan".
   * The class extends an abstract superclass UnaryFunction.
   */
  public final class Arctangente extends UnaryFunction {
  
  	/**
  	 * Class constructor specifying an Expression to apply the arctangent function.
  	 *
  	 * @param arg The Expression to apply the operation on
  	 * @throws IllegalConstruction If a null argument is passed
  	 */
  	public Arctangente(Expression arg) throws IllegalConstruction {
  		super(arg);
  		symbol = "atan";
  	}
  
  	@Override
  	public Real op(Real r) {
  		if (r.isNan()) {
  			return Real.nan();
  		}
  		if (r.isPlusInf()) {
  			return new Real(new java.math.BigDecimal(Math.PI / 2));
  		}
  		if (r.isMinusInf()) {
  			return new Real(new java.math.BigDecimal(-Math.PI / 2));
  		}
  
  		BigDecimal val = BigDecimalMath.atan(r.getValue(), Real.context);
  		return new Real(val);
  	}
  
  	@Override
  	public IntegerAtom op(IntegerAtom i) {
  		double atanVal = Math.atan(i.getValue());
  		return new IntegerAtom((int) Math.round(atanVal));
  	}
  
  	@Override
  	public Complex op(Complex c) {
  		org.apache.commons.numbers.complex.Complex val = c.getValue().atan();
  		return new Complex(val);
  	}
  
  	@Override
  	public Rationnal op(Rationnal q) {
  		double atanVal = Math.atan(q.getValue().doubleValue());
  		org.apache.commons.numbers.fraction.Fraction result = org.apache.commons.numbers.fraction.Fraction
  				.from(atanVal);
  		return new Rationnal(result);
  	}
  }