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 natural logarithm unary operation "ln".
   * The class extends an abstract superclass UnaryFunction.
   */
  public final class Ln extends UnaryFunction {
  
  	public Ln(Expression arg) throws IllegalConstruction {
  		super(arg);
  		symbol = "ln";
  	}
  
  	@Override
  	public Real op(Real r) {
  		if (r.isNan() || r.isMinusInf() || r.getValue().doubleValue() < 0) {
  			throw new IllegalArgumentException("Logarithm of negative number");
  		}
  		if (r.getValue().doubleValue() == 0) {
  			return Real.minusInf();
  		}
  		if (r.isPlusInf()) {
  			return Real.plusInf();
  		}
  
  		BigDecimal val = BigDecimalMath.log(r.getValue(), Real.context);
  		return new Real(val);
  	}
  
  	@Override
  	public IntegerAtom op(IntegerAtom i) {
  		if (i.getValue() < 0) {
  			throw new IllegalArgumentException("Logarithm of negative number");
  		}
  		double lnVal = Math.log(i.getValue());
  		return new IntegerAtom((int) Math.round(lnVal));
  	}
  
  	@Override
  	public Complex op(Complex c) {
  		org.apache.commons.numbers.complex.Complex val = c.getValue().log();
  		return new Complex(val);
  	}
  
  	@Override
  	public Rationnal op(Rationnal q) {
  		if (q.getValue().doubleValue() < 0) {
  			throw new IllegalArgumentException("Logarithm of negative number");
  		}
  		double lnVal = Math.log(q.getValue().doubleValue());
  		org.apache.commons.numbers.fraction.Fraction result = org.apache.commons.numbers.fraction.Fraction.from(lnVal);
  		return new Rationnal(result);
  	}
  }