package calculator;

public class CalcModel {
  private int calcValue;

  /**
   * Creates a model with no user values and a calculated value of zero.
   * 
   */
  public CalcModel() {
    this.calcValue = 0;
  }


  /**
   * Clears the user values and the calculated value.
   */
  public void clear() {
    this.calcValue = 0;
  }

  /**
   * Adds the calculated value by a user value.
   * 
   * @param userValue
   *          The value to add to the current calculated value by.
   */
  public void sum(int userValue) {
    this.calcValue += userValue;
  }

  /**
   * Subtracts the calculated value by a user value.
   * 
   * @param userValue
   *          The value to subtract from the current calculated value by.
   */
  public void subtract(int userValue) {
    this.calcValue -= userValue;
  }

  /**
   * Multiplies the calculated value by a user value.
   * 
   * @param userValue
   *          The value to multiply the current calculated value by.
   */
  public void multiply(int userValue) {
    this.calcValue *= userValue;
  }

  /**
   * Divides the calculated value by a user value.
   * 
   * @param userValue
   *          The value to multiply the current calculated value by.
   * @pre. userValue is not equivalent to zero.
   */
  public void divide(int userValue) {
    this.calcValue /= userValue;
  }

  /**
   * Get the current calculated value.
   * 
   * @return The current calculated value.
   */
  public int getCalcValue() {
    return this.calcValue;
  }

}