LineInfoGUI.java

import javafx.application.*;
import javafx.geometry.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.scene.input.*;
import javafx.scene.layout.*;
import javafx.scene.paint.*;
import javafx.scene.shape.*;
import javafx.scene.text.*;
import javafx.stage.*;
import java.time.*;
import java.time.format.DateTimeFormatter;

public class LineInfoGUI extends Application {

    private Pane pane;
    private BorderPane borderPane;
    private Circle startPoint, endPoint;
    private Line line;
    private Button distanceButton, midpointButton, vertHorzButton;
    private Text distanceText, midpointText, vertHorzText, timeText;
    private LineInfoDisplayer lineInfoDisplayer;

    private static final int CIRCLE_RADIUS = 5;

    public void start(Stage primaryStage) {
        borderPane = new BorderPane();

        pane = new Pane();
        pane.setOnMouseClicked(this::handleMouseClicks);
        borderPane.setCenter(pane);

        distanceText = new Text("");
        distanceButton = new Button("Calculate Distance");
        distanceButton.setOnAction(event -> {
            if (line != null) {
                lineInfoDisplayer =
                        LineInfoDisplayer.createLineInfoDisplayer(LineInfoDisplayer.InfoType.DISTANCE);
                assert lineInfoDisplayer != null;
                distanceText.setText(lineInfoDisplayer.getInfo(line));

            }
        });

        midpointText = new Text("");
        midpointButton = new Button("Calculate Midpoint");
        midpointButton.setOnAction(event -> {
            if (line != null) {
                lineInfoDisplayer =
                        LineInfoDisplayer.createLineInfoDisplayer(LineInfoDisplayer.InfoType.MIDPOINT);
                assert lineInfoDisplayer != null;
                midpointText.setText(lineInfoDisplayer.getInfo(line));
            }
        });

        vertHorzText = new Text("");
        vertHorzButton = new Button("Determine Vertical/Horizontal");
        vertHorzButton.setOnAction(event -> {
            if (line != null) {
                lineInfoDisplayer =
                        LineInfoDisplayer.createLineInfoDisplayer(LineInfoDisplayer.InfoType.VERTHORZ);
                assert lineInfoDisplayer != null;
                vertHorzText.setText(lineInfoDisplayer.getInfo(line));
            }
        });

        timeText = new Text("");

        TilePane distancePane = new TilePane(distanceButton, distanceText);
        distancePane.setAlignment(Pos.CENTER);
        TilePane midpointPane = new TilePane(midpointButton, midpointText);
        midpointPane.setAlignment(Pos.CENTER);
        TilePane vertHorzPane = new TilePane(vertHorzButton, vertHorzText);
        vertHorzPane.setAlignment(Pos.CENTER);
        TilePane timePane = new TilePane(timeText);
        timePane.setAlignment(Pos.CENTER);

        VBox controlBox = new VBox(distancePane, midpointPane, vertHorzPane, timePane);
        controlBox.setAlignment(Pos.CENTER);
        controlBox.setSpacing(15);

        borderPane.setBottom(controlBox);

        Scene scene = new Scene(borderPane, 500, 500, Color.WHITE);
        primaryStage.setTitle("Line Information");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void handleMouseClicks(MouseEvent event) {
        double x = event.getX();
        double y = event.getY();

        if (startPoint == null) { // no start point yet, set the start point
            startPoint = new Circle(x, y, CIRCLE_RADIUS);
            pane.getChildren().add(startPoint);
            createCoordinates(x, y);
            line = null;
        } else if (endPoint == null) { // start point, but not end point yet
            // set the end point
            endPoint = new Circle(x, y, CIRCLE_RADIUS);
            pane.getChildren().add(endPoint);
            createCoordinates(x, y);

            line = new Line(startPoint.getCenterX(), startPoint.getCenterY(), endPoint.getCenterX(), endPoint.getCenterY());
            pane.getChildren().add(line);
            timeStampGenerator();

        } else { // startPoint != null && endPoint !=null
            // both start and end are there, so this is starting a new line;
            // set a new start point
            pane.getChildren().clear();
            endPoint = null;
            line = null;
            distanceText.setText("");
            midpointText.setText("");
            vertHorzText.setText("");

            startPoint = new Circle(x, y, CIRCLE_RADIUS);
            pane.getChildren().add(startPoint);
            createCoordinates(x, y);
        }

    }

    private void createCoordinates(double x, double y) {
        String coordinateString = "(" + x + ", " + y + ")";
        Text coordinates = new Text(x - CIRCLE_RADIUS, y - CIRCLE_RADIUS - 2, coordinateString);
        pane.getChildren().add(coordinates);
    }

    private void timeStampGenerator() {
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("MMM dd, yyyy EEE " +
                "HH:mm:ss a");
        LocalDateTime currentLDT = LocalDateTime.now();
        String localDateTimeString = dateTimeFormatter.format(currentLDT);
        timeText.setText("Line created on " + localDateTimeString);
    }

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

}