/*
Progam: First Form - Basic Calculator

Function:   The purpose of the program is to add and subtract two numbers
            It also needs to have a clear button

Programmer: James Goudy ©2024

 */
package j2x_1_firstform;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.*;

// Class to create and manage a basic JFrame
class form1 {

    // remember that when a control is created
    // it has no dimensions, no location,
    // and its visibility is set to false.
    
    // create the frame
    JFrame jf1 = new JFrame("First Form");
    
    // create the lablels
    JLabel jlbl_Title = new JLabel();
    JLabel jlblBox1 = new JLabel();
    JLabel jlblBox2 = new JLabel();
    JLabel jlblAns = new JLabel();
    JLabel jlblAnsValue = new JLabel();
    
    // create the textfields
    JTextField jtxt1 = new JTextField();
    JTextField jtxt2 = new JTextField();
    
    // create the buttons
    JButton jbttnAdd = new JButton();
    JButton jbttnSub = new JButton();
    JButton jbttnClear = new JButton();
    
    // create a customize color
    Color myColor = new Color(210, 180, 140);
    
    // Constructor to initialize the form
    public form1() {
        
        int TitleSz = 24;       // Title Size
        int TextSz = 12;        // Text Size
             
        // Call the method to set up the JFrame
        setUpTheJFrame();

        // add Title label to the form
        setupLabelBox(jlbl_Title, 10, 10, "Calculator", TitleSz);
        
        // setup the first textfield with a lablel
        setupLabelBox(jlblBox1, 10, 50, "First Number",TextSz);
        setupTextFields(jtxt1, 150, 50,12);

        // setup the second textfield with a label
        setupLabelBox(jlblBox2, 10, 75, "Second Number", TextSz);
        setupTextFields(jtxt2, 150, 75,12);

        // setup the answer label and a labele to hold the answer
        setupLabelBox(jlblAns, 10, 100, "Answer",TextSz);
        setupLabelBox(jlblAnsValue, 150, 100, "---",TextSz);

        // setup the buttons
        setMathButtons(jbttnAdd, 10, 125, "+");
        setMathButtons(jbttnSub,60, 125,"-");
        setMathButtons(jbttnClear, 110, 125, "C");
    }

	// Private method to configure the JFrame's visual 
        // and behavioral properties
	private void setUpTheJFrame() {

		// Set the initial dimensions of the JFrame's window
		jf1.setSize(400, 250); 

		// Apply a custom background color to the content pane
                // The content pane is the area where items are added to 
                // the frame
		jf1.getContentPane().setBackground(myColor);  

		// Make the JFrame visible on the screen, 
                // allowing users to interact with it
		jf1.setVisible(true);

		// Center the JFrame on the user's screen for optimal visibility
		jf1.setLocationRelativeTo(null);

		// Specify the program's termination behavior 
                // when the JFrame is closed
		// Exit the program when the frame is closed
		jf1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  

		// Disable the default layout manager, allowing 
		// for manual component positioning
		 // Note: Manual layout can be more complex to manage
		jf1.setLayout(null); 
	}


    private void setupLabelBox(JLabel lbl, int xpos, int ypos, 
            String theText, float labelSize) {
        // Set the font size to 12 points
        // NOTE: Have to do this before we add the text
        lbl.setFont(lbl.getFont().deriveFont(labelSize));

        // Set the preferred size of the label
        lbl.setSize(150, (int)labelSize + 8);

        // Set the text content of the label
        lbl.setText(theText);

        // Make the label visible
        lbl.setVisible(true);

        // Position the label at coordinates (10, 10) within the window
        lbl.setLocation(xpos, ypos);

        // Add the label to the window's content pane
        jf1.add(lbl);  // Assuming jf1 is the main window object

        // Request the window to be redrawn, reflecting the added label
        jf1.repaint();
    }

    private void setupTextFields(JTextField jtxt, 
            int xpos, int ypos, float fsize) {
        // Set the font size to 12 points
        // NOTE: Have to do this before we add the text
        jtxt.setFont(jtxt.getFont().deriveFont(12f));

        // Set the preferred size of the label
        jtxt.setSize(100, (int)fsize + 8);

        // Set the text content of the label
        jtxt.setText("0");

        // Make the label visible
        jtxt.setVisible(true);

        // Position the label at coordinates (10, 10) within the window
        jtxt.setLocation(xpos, ypos);

        // Add the label to the window's content pane
        jf1.add(jtxt);  // Assuming jf1 is the main window object

        // Request the window to be redrawn, reflecting the added label
        jf1.repaint();
    }

    private void setMathButtons(JButton jbttnMath, int xpos, int ypos,
            String mathOp) {

        // Set the font size to 12 points
        // NOTE: Have to do this before we add the text
        jbttnMath.setFont(jbttnMath.getFont().deriveFont(12f));

        // Set the preferred size of the label
        jbttnMath.setSize(45, 45);

        // Set the text content of the label
        jbttnMath.setText(mathOp);

        // Make the label visible
        jbttnMath.setVisible(true);

        // Position the label at coordinates (xpos, ypos) within the window
        jbttnMath.setLocation(xpos, ypos);

        // This action listener listens for the mouse click
        jbttnMath.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
				// the string operator is passed to the function
                               
                mathCalc(mathOp);
                
                // in production, if there are complex operations
                // or many lines of code, then writing out
                // separate functions may be preferable
            }
        });

        // This key listener is for listening for the keyboard actions
        jbttnMath.addKeyListener(new KeyListener() {
            
            // For Reference
            @Override
            public void keyTyped(KeyEvent e) {

            }

            // listen only for the "Enter" key
            @Override
            public void keyPressed(KeyEvent e) {

                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    mathCalc(mathOp);
                }
            }

            // For Reference
            @Override
            public void keyReleased(KeyEvent e) {
                
            }
        });

        // Add the label to the window's content pane
        jf1.add(jbttnMath);  // Assuming jf1 is the main window object

        // Request the window to be redrawn, reflecting the added label
        jf1.repaint();

    }

    /**    Function to do the appropriate Math operation.
            Note that the operation sign is being passed to the function */
    private void mathCalc(String mathOp) {
        double ans = 0.0;

        try {
            switch (mathOp) {
                case "+" -> {
                    // Retreive the text from the textfield 
                    // and parse it into a double datatype
                    ans = Double.parseDouble(jtxt1.getText())
                            + Double.parseDouble(jtxt2.getText());
                    
                    // place the answer in the Answer Value label
                    jlblAnsValue.setText(String.valueOf(ans));
                }
                case "-" -> {
                    ans = Double.parseDouble(jtxt1.getText())
                            - Double.parseDouble(jtxt2.getText());
                    jlblAnsValue.setText(String.valueOf(ans));
                }
                case "C" -> {
                    // Clear the textfields by setting the 
                    // contents to an empty string
                    jtxt1.setText("");
                    jtxt2.setText("");
                    jlblAnsValue.setText(""); 
                    
                    // Place the cursor in the first textfield
                    // using the requestFocus command
                    jtxt1.requestFocus();
                }

            }
        } catch (Exception e) {
            jlblAnsValue.setText("You had an error");
            jtxt1.setText("");
            jtxt2.setText("");
            jtxt1.requestFocus();
        }
    }

}

public class J2x_1_firstform {

    public static void main(String[] args) {
        // create a frame window
        form1 myForm = new form1();
    }

}