/****************************************************************************
**
** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
** information about Qt Commercial License Agreements.
** See http://www.trolltech.com/gpl/ for GPL licensing information.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include <QtGui>

#include <math.h>

#include "button.h"
#include "calculator.h"

Calculator::Calculator(QWidget *parent)
    : QDialog(parent)
{
    sumInMemory = 0.0;
    sumSoFar = 0.0;
    factorSoFar = 0.0;
    waitingForOperand = true;

    display = new QLineEdit("0");
    display->setReadOnly(true);
    display->setAlignment(Qt::AlignRight);
    display->setMaxLength(15);
    display->installEventFilter(this);

    QFont font = display->font();
    font.setPointSize(font.pointSize() + 8);
    display->setFont(font);

    QColor digitColor(150, 205, 205);
    QColor backspaceColor(225, 185, 135);
    QColor memoryColor(100, 155, 155);
    QColor operatorColor(155, 175, 195);

    for (int i = 0; i < NumDigitButtons; ++i) {
	digitButtons[i] = createButton(QString::number(i), digitColor,
                                       SLOT(digitClicked()));
    }

    pointButton = createButton(tr("."), digitColor, SLOT(pointClicked()));
    changeSignButton = createButton(tr("±"), digitColor, SLOT(changeSignClicked()));

    backspaceButton = createButton(tr("Backspace"), backspaceColor,
                                   SLOT(backspaceClicked()));
    clearButton = createButton(tr("Clear"), backspaceColor, SLOT(clear()));
    clearAllButton = createButton(tr("Clear All"), backspaceColor.light(120),
                                  SLOT(clearAll()));

    clearMemoryButton = createButton(tr("MC"), memoryColor,
                                     SLOT(clearMemory()));
    readMemoryButton = createButton(tr("MR"), memoryColor, SLOT(readMemory()));
    setMemoryButton = createButton(tr("MS"), memoryColor, SLOT(setMemory()));
    addToMemoryButton = createButton(tr("M+"), memoryColor,
                                     SLOT(addToMemory()));

    divisionButton = createButton(tr("÷"), operatorColor,
                                  SLOT(multiplicativeOperatorClicked()));
    timesButton = createButton(tr("×"), operatorColor,
                               SLOT(multiplicativeOperatorClicked()));
    minusButton = createButton(tr("-"), operatorColor,
                               SLOT(additiveOperatorClicked()));
    plusButton = createButton(tr("+"), operatorColor,
                              SLOT(additiveOperatorClicked()));

    squareRootButton = createButton(tr("Sqrt"), operatorColor,
                                    SLOT(unaryOperatorClicked()));
    powerButton = createButton(tr("x²"), operatorColor,
                               SLOT(unaryOperatorClicked()));
    reciprocalButton = createButton(tr("1/x"), operatorColor,
                                    SLOT(unaryOperatorClicked()));
    equalButton = createButton(tr("="), operatorColor.light(120),
                               SLOT(equalClicked()));

    QGridLayout *mainLayout = new QGridLayout;
    mainLayout->setSizeConstraint(QLayout::SetFixedSize);

    mainLayout->addWidget(display, 0, 0, 1, 6);
    mainLayout->addWidget(backspaceButton, 1, 0, 1, 2);
    mainLayout->addWidget(clearButton, 1, 2, 1, 2);
    mainLayout->addWidget(clearAllButton, 1, 4, 1, 2);

    mainLayout->addWidget(clearMemoryButton, 2, 0);
    mainLayout->addWidget(readMemoryButton, 3, 0);
    mainLayout->addWidget(setMemoryButton, 4, 0);
    mainLayout->addWidget(addToMemoryButton, 5, 0);

    for (int i = 1; i < NumDigitButtons; ++i) {
        int row = ((9 - i) / 3) + 2;
        int column = ((i - 1) % 3) + 1;
        mainLayout->addWidget(digitButtons[i], row, column);
    }

    mainLayout->addWidget(digitButtons[0], 5, 1);
    mainLayout->addWidget(pointButton, 5, 2);
    mainLayout->addWidget(changeSignButton, 5, 3);

    mainLayout->addWidget(divisionButton, 2, 4);
    mainLayout->addWidget(timesButton, 3, 4);
    mainLayout->addWidget(minusButton, 4, 4);
    mainLayout->addWidget(plusButton, 5, 4);

    mainLayout->addWidget(squareRootButton, 2, 5);
    mainLayout->addWidget(powerButton, 3, 5);
    mainLayout->addWidget(reciprocalButton, 4, 5);
    mainLayout->addWidget(equalButton, 5, 5);
    setLayout(mainLayout);

    setWindowTitle(tr("Calculator"));
}

bool Calculator::eventFilter(QObject *target, QEvent *event)
{
    if (target == display) {
        if (event->type() == QEvent::MouseButtonPress
                || event->type() == QEvent::MouseButtonDblClick
                || event->type() == QEvent::MouseButtonRelease
                || event->type() == QEvent::ContextMenu) {
            QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
            if (mouseEvent->buttons() & Qt::LeftButton) {
                QPalette newPalette = palette();
                newPalette.setColor(QPalette::Base,
                                    display->palette().color(QPalette::Text));
                newPalette.setColor(QPalette::Text,
                                    display->palette().color(QPalette::Base));
                display->setPalette(newPalette);
            } else {
                display->setPalette(palette());
            }
            return true;
        }
    }
    return QDialog::eventFilter(target, event);
}

void Calculator::digitClicked()
{
    Button *clickedButton = qobject_cast<Button *>(sender());
    int digitValue = clickedButton->text().toInt();
    if (display->text() == "0" && digitValue == 0.0)
        return;

    if (waitingForOperand) {
        display->clear();
	waitingForOperand = false;
    }
    display->setText(display->text() + QString::number(digitValue));
}

void Calculator::unaryOperatorClicked()
{
    Button *clickedButton = qobject_cast<Button *>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();
    double result;

    if (clickedOperator == tr("Sqrt")) {
        if (operand < 0.0) {
            abortOperation();
            return;
        }
        result = sqrt(operand);
    } else if (clickedOperator == tr("x²")) {
        result = pow(operand, 2.0);
    } else if (clickedOperator == tr("1/x")) {
        if (operand == 0.0) {
	    abortOperation();
	    return;
        }
        result = 1.0 / operand;
    }
    display->setText(QString::number(result));
    waitingForOperand = true;
}

void Calculator::additiveOperatorClicked()
{
    Button *clickedButton = qobject_cast<Button *>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();

    if (!pendingMultiplicativeOperator.isEmpty()) {
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
	    return;
        }
        display->setText(QString::number(factorSoFar));
        operand = factorSoFar;
        factorSoFar = 0.0;
        pendingMultiplicativeOperator.clear();
    }

    if (!pendingAdditiveOperator.isEmpty()) {
        if (!calculate(operand, pendingAdditiveOperator)) {
            abortOperation();
	    return;
        }
        display->setText(QString::number(sumSoFar));
    } else {
        sumSoFar = operand;
    }

    pendingAdditiveOperator = clickedOperator;
    waitingForOperand = true;
}

void Calculator::multiplicativeOperatorClicked()
{
    Button *clickedButton = qobject_cast<Button *>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();

    if (!pendingMultiplicativeOperator.isEmpty()) {
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
	    return;
        }
        display->setText(QString::number(factorSoFar));
    } else {
        factorSoFar = operand;
    }

    pendingMultiplicativeOperator = clickedOperator;
    waitingForOperand = true;
}

void Calculator::equalClicked()
{
    double operand = display->text().toDouble();

    if (!pendingMultiplicativeOperator.isEmpty()) {
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
	    return;
        }
        operand = factorSoFar;
        factorSoFar = 0.0;
        pendingMultiplicativeOperator.clear();
    }
    if (!pendingAdditiveOperator.isEmpty()) {
        if (!calculate(operand, pendingAdditiveOperator)) {
            abortOperation();
	    return;
        }
        pendingAdditiveOperator.clear();
    } else {
        sumSoFar = operand;
    }

    display->setText(QString::number(sumSoFar));
    sumSoFar = 0.0;
    waitingForOperand = true;
}

void Calculator::pointClicked()
{
    if (waitingForOperand)
        display->setText("0");
    if (!display->text().contains("."))
        display->setText(display->text() + tr("."));
    waitingForOperand = false;
}

void Calculator::changeSignClicked()
{
    QString text = display->text();
    double value = text.toDouble();

    if (value > 0.0) {
        text.prepend(tr("-"));
    } else if (value < 0.0) {
        text.remove(0, 1);
    }
    display->setText(text);
}

void Calculator::backspaceClicked()
{
    if (waitingForOperand)
        return;

    QString text = display->text();
    text.chop(1);
    if (text.isEmpty()) {
        text = "0";
        waitingForOperand = true;
    }
    display->setText(text);
}

void Calculator::clear()
{
    if (waitingForOperand)
        return;

    display->setText("0");
    waitingForOperand = true;
}

void Calculator::clearAll()
{
    sumSoFar = 0.0;
    factorSoFar = 0.0;
    pendingAdditiveOperator.clear();
    pendingMultiplicativeOperator.clear();
    display->setText("0");
    waitingForOperand = true;
}

void Calculator::clearMemory()
{
    sumInMemory = 0.0;
}

void Calculator::readMemory()
{
    display->setText(QString::number(sumInMemory));
    waitingForOperand = true;
}

void Calculator::setMemory()
{
    equalClicked();
    sumInMemory = display->text().toDouble();
}

void Calculator::addToMemory()
{
    equalClicked();
    sumInMemory += display->text().toDouble();
}

Button *Calculator::createButton(const QString &text, const QColor &color,
                                 const char *member)
{
    Button *button = new Button(text, color);
    connect(button, SIGNAL(clicked()), this, member);
    return button;
}

void Calculator::abortOperation()
{
    clearAll();
    display->setText(tr("####"));
}

bool Calculator::calculate(double rightOperand, const QString &pendingOperator)
{
    if (pendingOperator == tr("+")) {
        sumSoFar += rightOperand;
    } else if (pendingOperator == tr("-")) {
        sumSoFar -= rightOperand;
    } else if (pendingOperator == tr("×")) {
        factorSoFar *= rightOperand;
    } else if (pendingOperator == tr("÷")) {
	if (rightOperand == 0.0)
	    return false;
	factorSoFar /= rightOperand;
    }
    return true;
}
