/***************************************************************************
                          kmymoneycalculator.h  -  description
                             -------------------
    begin                : Sat Oct 19 2002
    copyright            : (C) 2000-2002 by Michael Edwardes
    email                : mte@users.sourceforge.net
                           Javier Campos Morales <javi_c@users.sourceforge.net>
                           Felix Rodriguez <frodriguez@users.sourceforge.net>
                           John C <thetacoturtle@users.sourceforge.net>
                           Thomas Baumgart <ipwizard@users.sourceforge.net>
                           Kevin Tambascio <ktambascio@users.sourceforge.net>
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef KMYMONEYCALCULATOR_H
#define KMYMONEYCALCULATOR_H

// ----------------------------------------------------------------------------
// QT Includes

#include <QWidget>
#include <QLayout>
#include <QLabel>
#include <QKeyEvent>

// ----------------------------------------------------------------------------
// KDE Includes

#include <kpushbutton.h>

// ----------------------------------------------------------------------------
// Project Includes

#include "kmm_widgets_export.h"

/**
  *@author Thomas Baumgart
  */

/**
  * This class implements a simple electronic calculator with the
  * ability of addition, subtraction, multiplication and division
  * and percentage calculation. Memory locations are not available.
  *
  * The first operand and operation can be loaded from an external
  * source to switch from an edit-widget to the calculator widget
  * without having the user to re-type the data. See setInitialValues()
  * for details.
  */
class KMM_WIDGETS_EXPORT kMyMoneyCalculator : public QFrame
{
  Q_OBJECT
public:
  kMyMoneyCalculator(QWidget* parent = 0);
  ~kMyMoneyCalculator();

  /**
    * This methods is used to extract the result of the last
    * calculation. The fractional part is separated from the
    * integral part by the character setup using setComma().
    *
    * @return QString representing the result of the
    *         last operation
    */
  const QString result() const;

  /**
    * This method is used to set the character to be used
    * as the separator between the integer and fractional part
    * of an operand. Upon creation of the object, m_comma is
    * set to the current locale setting of KDE's decimalSymbol.
    *
    * @param ch QChar representing the character to be used
    */
  void setComma(const QChar ch) {
    m_comma = ch;
  };

  /**
    * This method is used to preset the first operand and start
    * execution of an operation. This method is currently used
    * by kMyMoneyEdit. If @p ev is 0, then no operation will be
    * started.
    *
    * @param value reference to QString representing the operands value
    * @param ev    pointer to QKeyEvent representing the operation's key
    */
  void setInitialValues(const QString& value, QKeyEvent* ev);

signals:
  /**
    * This signal is emitted, when a new result is available
    */
  void signalResultAvailable();

protected:
  void keyPressEvent(QKeyEvent* ev);

  /**
    * This method is used to transform a double into a QString
    * and removing any trailing 0's and decimal separators
    *
    * @param val reference to double value to be converted
    * @return QString object containing the converted value
    */
  QString normalizeString(const double& val);

protected slots:
  /**
    * This method appends the digit represented by the parameter
    * to the current operand
    *
    * @param button integer value of the digit to be added in the
    *               range [0..9]
    */
  void digitClicked(int button);

  /**
    * This methods starts the operation contained in the parameter
    *
    * @param button The Qt::Keycode for the button pressed or clicked
    */
  void calculationClicked(int button);

  /**
    * This method appends a period (comma) to initialize the fractional
    * part of an operand. The period is only appended once.
    */
  void commaClicked();

  /**
    * This method reverses the sign of the current operand
    */
  void plusminusClicked();

  /**
    * This method clears the current operand
    */
  void clearClicked();

  /**
    * This method clears all registers
    */
  void clearAllClicked();

  /**
    * This method executes the percent operation
    */
  void percentClicked();

  /**
    * This method updates the display of the calculator with
    * the text passed as argument
    *
    * @param str reference to QString containing the new display contents
    */
  void changeDisplay(const QString& str);

private:
  /**
    * This member variable stores the current (second) operand
    */
  QString operand;

  /**
    * This member variable stores the last result
    */
  QString m_result;

  /**
    * This member variable stores the representation of the
    * character to be used to separate the integer and fractional
    * part of numbers. The internal representation is always a period.
    */
  QChar m_comma;

  /**
    * The numeric representation of a stacked first operand
    */
  double op0;

  /**
    * The numeric representation of the first operand
    */
  double op1;

  /**
    * This member stores the operation to be performed between
    * the first and the second operand.
    */
  int op;

  /**
   * This member stores a pending addition operation
   */
  int stackedOp;

  /**
    * This member stores a pointer to the display area
    */
  QLabel *display;

  /**
    * This member array stores the pointers to the various
    * buttons of the calculator. It is setup during the
    * constructor of this object
    */
  KPushButton *buttons[20];

  /**
    * This enumeration type stores the values used for the
    * various keys internally
    */
  enum {
    /* 0-9 are used by digits */
    COMMA = 10,
    /*
     * make sure, that PLUS through EQUAL remain in
     * the order they are. Otherwise, check the calculation
     * signal mapper
     */
    PLUS,
    MINUS,
    SLASH,
    STAR,
    EQUAL,
    PLUSMINUS,
    PERCENT,
    CLEAR,
    CLEARALL,
    /* insert new buttons before this line */
    MAX_BUTTONS
  };

  /**
    * This flag signals, if the operand should be replaced upon
    * a digit key pressure. Defaults to false and will be set, if
    * setInitialValues() is called without an operation.
    */
  bool m_clearOperandOnDigit;
};

#endif
