// CalcModel.java
// Fred Swartz - December 2004
// Paolo Bucci -- November 2009 (modified)
// Model
//     This model is completely independent of the user interface.
//     It could as easily be used by a command line or web interface.

import java.math.BigInteger;

public class CalcModel {
    //... Constants
    private static final String INITIAL_VALUE = "1"; // identity for multiply

    //... Member variable defining state of calculator.
    private BigInteger m_total;  // The total current value state.

    //============================================================== constructor
    /** Constructor */
    CalcModel() {
        reset();
    }

    //==================================================================== reset
    /** Reset to initial value. */
    public void reset() {
        m_total = new BigInteger(INITIAL_VALUE);
    }

    //=============================================================== multiplyBy
    /** Multiply current total by a number.
    *@param operand Number (as string) to multiply total by.
    */
    public void multiplyBy(String operand) {
        m_total = m_total.multiply(new BigInteger(operand));
    }

    //================================================================= setValue
    /** Set the total value.
    *@param value New value that should be used for the calculator total.
    */
    public void setValue(String value) {
        m_total = new BigInteger(value);
    }

    //================================================================= getValue
    /** Return current calculator total. */
    public String getValue() {
        return m_total.toString();
    }
}