package net.sven_eisenhauer.swa_prakt1;

public class ExpressionIterator implements ArithmeticIterator {
	private ArithmeticExpression baseNode;
	
	public ExpressionIterator(ArithmeticExpression baseNode) {
		this.baseNode = baseNode;
	}

	public void print() {
		if(baseNode instanceof ArithmeticVariable) {
			System.out.print(((ArithmeticVariable) baseNode).getName());
		} else {
			ArithmeticOperation actOperation = (ArithmeticOperation) baseNode;
			ArithmeticIterator leftIter = new ExpressionIterator(actOperation.getLeftOperand());
			ArithmeticIterator rightIter = new ExpressionIterator(actOperation.getRightOperand());
			System.out.print("(");
			leftIter.print();
			System.out.print(actOperation.getOperationSign());
			rightIter.print();
			System.out.print(")");
		}
	}
	
	public Number evaluate() {
		if(baseNode instanceof ArithmeticVariable) {
			return ((ArithmeticVariable) baseNode).getValue();
		} else {
			ArithmeticOperation actOperation = (ArithmeticOperation) baseNode;
			ArithmeticIterator leftIter = new ExpressionIterator(actOperation.getLeftOperand());
			ArithmeticIterator rightIter = new ExpressionIterator(actOperation.getRightOperand());
			Number leftVal = leftIter.evaluate();
			Number rightVal = rightIter.evaluate();
			if(actOperation instanceof ArithmeticAddition) {
				return leftVal.doubleValue() + rightVal.doubleValue();
			} else if(actOperation instanceof ArithmeticSubstraction) {
				return leftVal.doubleValue() - rightVal.doubleValue();
			} else if(actOperation instanceof ArithmeticDivision) {
				return leftVal.doubleValue() / rightVal.doubleValue();
			} else if(actOperation instanceof ArithmeticMultiplication) {
				return leftVal.doubleValue() * rightVal.doubleValue();
			} else {
				return null;
			}
		}
	}
}