package infixModel;
/**
 * Represents the calculator itself, without its GUI and separate from its states.
 * Copyright (C) 2004 Dung X. Nguyen. All rights Reserved.
 */
public class InfixCalc {
  /**
   * accumulated computation
   */
  private double _acc; 
  /**
   * current display string
   */
  private String _display;
  /**
   * Current pending operation
   */
  private IBinOp _pendingOp; 
  /**
   * A no-op
   */
  private final IBinOp _noOp = new IBinOp() {
    public double compute(double n1, double n2) {
      return Double.parseDouble(_display);
    }
  };
  
  /**
   * The current state
   */
  private ACalcState _curState; 
  
  
  
  /**
   * Inialize this Calculator to the "clear" state.
   */
  public InfixCalc() {
    clear();
  }
  
  
  /**
   * Enters a digit.
   * @param c '0' <= c <= '9'.
   * @return accumulated input.
   */
  public final String enterDigit(char c) {
    System.out.println("Infix Calc enter digit " + c + " : pre display " + _display);
    _curState.enterDigit(this, c);
    System.out.println("Infix Calc enter digit: post display " + _display);
    return _display;
  }
  
  /**
   * Enters a decimal point
   */
  public final String enterPoint() {
    _curState.enterPoint(this);
    System.out.println("Infix Calc enter point: post display " + _display);
    return _display;
  }
  
  /**
   * Perform the pending operation, and prepare to add whatever is computed so
   * far to the operand that will be entered next and return the resulting String.
   * @param op The new pending operation.
   */
  public final String enterOp(IBinOp op) {
    _curState.enterOp(this, op);
    System.out.println("Infix Calc enter op: post display " + _display);
    return _display;
  }
  
  /**
   * Compute the current operation and return the result String.
   */
  public final String enterEqual() {
    _curState.enterEqual(this);
    System.out.println("Infix Calc enter equal: post display " + _display);
    return _display;
  }
  
  /**
   * Set this Calculator to the "clear" state where all internal memories are
   * set to zero and the pending operation is a no-op.
   */
  public final String clear() {
    _acc = 0;
    _curState = StartState.Singleton;
    _pendingOp = _noOp;
    _display = "0";
    //        System.out.println("Clear All!");
    return _display;
  }
  
  /**
   * Gets the current accumulator value
   * @return The current accumulator value
   */
  final double getAcc() {
    return _acc;
  }
  
  /**
   * Sets the accumulator value
   * @param a The new accumulator value
   */
  final void setAcc(double a) {
    _acc = a;
  }
  
  /**
   * Sets the display string
   * @param d The new display string
   */
  final void setDisplay(String d) {
    _display = d;
  }
  
  /**
   * Get the current display string
   * @return The current display string
   */
  final String getDisplay() {
    return _display;
  }
  
  /**
   * Sets the pending operation
   * @param op The new pending operation
   */
  final void setPendingOp(IBinOp op) {
    _pendingOp = op;
  }
  
  /**
   * Get the pending operation
   * 
   * @return The pending operation
   */
  final IBinOp getPendingOp() {
    return _pendingOp;
  }
  
  /**
   * Sets the pending operation to a no-op
   */
  final void setNoOp() {
    _pendingOp = _noOp;
  }
  
  /**
   * Sets the current state.
   * @param curState The new current state 
   */
  final void setCurState(ACalcState curState) {
    _curState = curState;
  }
  
  /**
   * Get the current state
   * @return The current state
   */
  final ACalcState getCurState() {
    return _curState;
  }
}