package zadanie4;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.HashMap;
import java.util.Map;

public class Calc {

    Map<String, Calculation> map = new HashMap<>();

    public Calc(){
        map.put("+", new AddCalculation());
        map.put("-", new SubtractCalc());
        map.put("*", new MultiplyCalc());
        map.put("/", new DivideCalc());
    }

    public String doCalc (String cmd) {
        try{
            String [] arr = cmd.split(" +");
            BigDecimal op1 = new BigDecimal(arr[0]);
            BigDecimal op2 = new BigDecimal(arr[2]);
            Calculation calculation = map.get(arr[1]);
            return calculation.calculate(op1, op2).toString();
        } catch(Exception ex){
            return "Invalid command to calc";
        }
    }

    interface Calculation {
        BigDecimal calculate (BigDecimal op1, BigDecimal op2);
    }

    class AddCalculation implements Calculation{
        public BigDecimal calculate (BigDecimal op1, BigDecimal op2){
            return op1.add(op2);
        }
    }

    class SubtractCalc implements Calculation{
        public BigDecimal calculate (BigDecimal op1, BigDecimal op2){
            return op1.subtract(op2);
        }
    }

    class DivideCalc implements Calculation{
        public BigDecimal calculate (BigDecimal op1, BigDecimal op2){
            return op1.divide(op2, 7, RoundingMode.HALF_UP);
        }
    }

    class MultiplyCalc implements Calculation{
        public BigDecimal calculate (BigDecimal op1, BigDecimal op2){
            return op1.multiply(op2);
        }
    }

}