#include "rekenmachine.h"
#include "ui_rekenmachine.h"

double currentValue = 0.0;
double prevValue = 0.0;
enum LastButton {plus, min, equals, multi, null};
LastButton lastButton = null;

Rekenmachine::Rekenmachine(QWidget *parent) : QMainWindow(parent), ui(new Ui::Rekenmachine)
{
    ui->setupUi(this);

    ui->Display->setText(QString::number(currentValue));
    QPushButton *buttons[3];
    for (int i = 0; i < 3; ++i)
    {
        QString buttonName = "Button" + QString::number(i);
        buttons[i] = Rekenmachine::findChild<QPushButton *>(buttonName);
        connect(buttons[i], SIGNAL(released()), this, SLOT(pressNumber()));
    }

    connect(ui->Add, SIGNAL(released()), this, SLOT(pressMath()));
    connect(ui->Subtract, SIGNAL(released()), this, SLOT(pressMath()));
    connect(ui->Multiply, SIGNAL(released()), this, SLOT(pressMath()));
    connect(ui->Result, SIGNAL(released()), this, SLOT(pressEqual()));
}

Rekenmachine::~Rekenmachine()
{
    delete ui;
}

void Rekenmachine::pressNumber()
{
    QPushButton *button = (QPushButton *)sender();
    QString buttonValue = button->text();
    QString displayValue= ui->Display->text();
    if (displayValue.toDouble() == 0 || displayValue.toDouble() == 0.0)
    {
        ui->Display->setText(buttonValue);
        currentValue = buttonValue.toDouble();
    }
    else
    {
        ui->Display->setText(QString::number((displayValue + buttonValue).toDouble()));
        currentValue = (displayValue + buttonValue).toDouble();
    }
}

void Rekenmachine::pressMath()
{
    lastButton = null;
    prevValue = currentValue;
    ui->lineEdit->setText(QString::number(prevValue));

    QPushButton *button = (QPushButton *)sender();
    if (button->text() == "+")
    {
        lastButton = plus;
    }
    if (button->text() == "-")
    {
        lastButton = min;
    }
    if (button->text() == "*")
    {
        lastButton = multi;
    }
    currentValue = 0;
    ui->Display->setText(QString::number(currentValue));
}

void Rekenmachine::pressEqual()
{
    if (lastButton = plus)
    {
        currentValue = prevValue + currentValue;
    }
    if (lastButton = min)
    {
        currentValue = prevValue - currentValue;
    }
    if (lastButton = multi)
    {
        currentValue = prevValue * currentValue;
    }
    ui->Display->setText(QString::number(currentValue));
}