package jisuanji;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class CalculatorGUI extends JFrame {
    private JTextField display;
    private Calculator calculator = new Calculator();
    private double firstNumber = 0;
    private double secondNumber = 0;
    private String operation = "";
    private boolean isOperationClicked = false;

    public CalculatorGUI() {
        setTitle("简易计算器");
        setSize(400, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);

        display = new JTextField();
        display.setEditable(false);
        display.setFont(new Font("Arial", Font.PLAIN, 40));
        display.setHorizontalAlignment(JTextField.RIGHT);
        display.setBorder(BorderFactory.createLineBorder(Color.BLACK));

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(4, 4, 10, 10));

        String[] buttons = {
                "7", "8", "9", "/",
                "4", "5", "6", "*",
                "1", "2", "3", "-",
                "0", ".", "=", "+"
        };

        for (String buttonText : buttons) {
            JButton button = new JButton(buttonText);
            button.setFont(new Font("Arial", Font.PLAIN, 24));
            button.addActionListener(new ButtonClickListener());
            panel.add(button);
        }

        add(display, BorderLayout.NORTH);
        add(panel, BorderLayout.CENTER);

        setVisible(true);
    }

    private class ButtonClickListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            String command = e.getActionCommand();

            if ("0123456789.".indexOf(command) >= 0) {
                display.setText(display.getText() + command);
                isOperationClicked = false;
            } else if ("+*/-=".indexOf(command) >= 0) {
                if (!isOperationClicked) {
                    firstNumber = Double.parseDouble(display.getText());
                    operation = command;
                    isOperationClicked = true;
                    display.setText("");
                } else if (command.equals("=")) {
                    secondNumber = Double.parseDouble(display.getText());
                    double result = 0;
                    switch (operation) {
                        case "+":
                            result = calculator.add(firstNumber, secondNumber);
                            break;
                        case "-":
                            result = calculator.subtract(firstNumber, secondNumber);
                            break;
                        case "*":
                            result = calculator.multiply(firstNumber, secondNumber);
                            break;
                        case "/":
                            result = calculator.divide(firstNumber, secondNumber);
                            break;
                    }
                    display.setText(String.valueOf(result));
                    isOperationClicked = false;
                }
            }
        }
    }

    public static void main(String[] args) {
        new CalculatorGUI();
    }
}