refactor: enhance Application and Base classes for improved UI interaction and key handling

src/Application.java

@@ -1,25 +1,249 @@
 package src;
 
 import javafx.fxml.FXML;
+import javafx.scene.control.Label;
+
+import java.util.*;
 
 public class Application extends Base {
-    public Application() {
+    private String piBuffer = "";
-        super("Hello FXML", 675, 600);
-    }
-
     @FXML
-    private void sayHello() {
+    private Label label;
-        System.out.println("Hello from FXML!");
+    private String formula = "";
-    }
+    private boolean lastInputWasError = false;
 
-    protected void on_button_click(String label) {
+    public Application() {
-        System.out.println("Button clicked: " + label);
+        super("Calci UwU", 675, 600);
     }
 
-
     @Override
     public void initUi() {
-        loadUi("./hello.fxml");
+        loadUi("./hello.fxml", () -> {
+            label = getById("label");
+            label.setText("");
+        });
+    }
+
+    @Override
+    protected void on_key_press(javafx.scene.input.KeyEvent event) {
+        String key = event.getText();
+        javafx.scene.input.KeyCode code = event.getCode();
+
+        if (key.equalsIgnoreCase("p")) {
+            piBuffer = "p";
+            return;
+        } else if (piBuffer.equals("p") && key.equalsIgnoreCase("i")) {
+            on_button_click("PI");
+            piBuffer = "";
+            return;
+        } else {
+            piBuffer = "";
+        }
+
+        if (code == javafx.scene.input.KeyCode.ENTER) key = "=";
+        else if (code == javafx.scene.input.KeyCode.ESCAPE) key = "CLR";
+        else if (code == javafx.scene.input.KeyCode.ADD) key = "+";
+        else if (code == javafx.scene.input.KeyCode.SUBTRACT) key = "-";
+        else if (code == javafx.scene.input.KeyCode.MULTIPLY) key = "*";
+        else if (code == javafx.scene.input.KeyCode.DIVIDE) key = "/";
+        else if (code == javafx.scene.input.KeyCode.DECIMAL) key = ".";
+        else if (code.isKeypadKey()) {
+            switch (code) {
+                case NUMPAD0: key = "0"; break;
+                case NUMPAD1: key = "1"; break;
+                case NUMPAD2: key = "2"; break;
+                case NUMPAD3: key = "3"; break;
+                case NUMPAD4: key = "4"; break;
+                case NUMPAD5: key = "5"; break;
+                case NUMPAD6: key = "6"; break;
+                case NUMPAD7: key = "7"; break;
+                case NUMPAD8: key = "8"; break;
+                case NUMPAD9: key = "9"; break;
+                default: break;
+            }
+        }
+
+        if (code == javafx.scene.input.KeyCode.BACK_SPACE && event.isControlDown()) {
+            this.formula = "";
+            this.label.setText(formula);
+            return;
+        }
+
+       if (code == javafx.scene.input.KeyCode.BACK_SPACE || code == javafx.scene.input.KeyCode.DELETE) {
+            if (code == javafx.scene.input.KeyCode.DELETE) {
+                this.formula = "";
+                this.label.setText(formula);
+                return;
+            }
+            String trimmed = this.formula.trim();
+            if (trimmed.isEmpty()) {
+                this.label.setText(formula);
+                return;
+            }
+
+            String[] tokens = trimmed.split(" ");
+            if (tokens.length > 0) {
+                // remove last token
+                tokens = Arrays.copyOf(tokens, tokens.length - 1);
+                this.formula = String.join(" ", tokens);
+            } else {
+                this.formula = "";
+            }
+
+            this.label.setText(formula);
+            return;
+        }
+
+        if (key == null || key.isEmpty()) {
+            return;
+        }
+
+        if (!key.matches("[0-9\\+\\-\\*/=\\.]") && !"CLR".equals(key)) {
+            return;
+        }
+
+        on_button_click(key);
+    }
+
+    @Override
+    protected void on_button_click(String label) {
+        if ("PI".equals(label)) {
+            this.formula += " PI ";
+            this.label.setText(formula);
+            return;
+        }
+
+        if (lastInputWasError) {
+            this.formula = "";
+            lastInputWasError = false;
+        }
+
+        String trimmed = this.formula.trim();
+
+        if ("+/-".equals(label)) {
+            String[] tokens = trimmed.split(" ");
+            if (tokens.length == 0) return;
+            String last = tokens[tokens.length - 1];
+            if (last.matches("-?\\d+(\\.\\d+)?")) {
+                if (last.startsWith("-")) {
+                    tokens[tokens.length - 1] = last.substring(1);
+                } else {
+                    tokens[tokens.length - 1] = "-" + last;
+                }
+                this.formula = String.join(" ", tokens);
+                this.label.setText(formula);
+            }
+            return;
+        }
+
+        if ("+-*/".contains(label)) {
+            if (label.equals("-") && (trimmed.isEmpty() || trimmed.matches(".*[\\+\\-\\*/]$"))) {
+                this.formula += "-";
+                this.label.setText(formula);
+                return;
+            }
+            if (trimmed.isEmpty()) return;
+            if (trimmed.matches(".*[\\+\\-\\*/]$")) return;
+            this.formula += " " + label + " ";
+        } else if ("=".equals(label)) {
+            if (trimmed.isEmpty() || trimmed.matches(".*[\\+\\-\\*/]$")) return;
+            solve();
+        } else if ("CLR".equals(label)) {
+            this.formula = "";
+        } else if (".".equals(label)) {
+            String[] tokens = trimmed.split(" ");
+            String last = tokens.length > 0 ? tokens[tokens.length - 1] : "";
+            if (!last.contains(".") && last.matches("\\d+")) {
+                this.formula += ".";
+            }
+        } else {
+            this.formula += label;
+        }
+
+        this.label.setText(formula);
+    }
+
+    private void solve() {
+        String expr = this.formula.trim();
+        if (expr.isEmpty()) {
+            this.formula = "";
+            return;
+        }
+        try {
+            double result = eval(expr);
+            if (result == (long) result) {
+                this.formula = String.valueOf((long) result);
+            } else {
+                this.formula = String.valueOf(result);
+            }
+        } catch (Exception e) {
+            this.formula = "ERR";
+            lastInputWasError = true;
+        }
+    }
+
+    private double eval(String expr) {
+        String[] rawTokens = expr.split("\\s+");
+        List<String> tokens = new ArrayList<>();
+
+        for (int i = 0; i < rawTokens.length; i++) {
+            String t = rawTokens[i];
+            if (t.equals("-")) {
+                if (i == 0 || rawTokens[i - 1].matches("[\\+\\-\\*/]")) {
+                    if (i + 1 < rawTokens.length && rawTokens[i + 1].matches("[0-9.]+")) {
+                        tokens.add("-" + rawTokens[i + 1]);
+                        i++;
+                        continue;
+                    }
+                }
+            }
+            if (t.equals("PI")) {
+                tokens.add(String.valueOf(Math.PI));
+                continue;
+            }
+            tokens.add(t);
+        }
+
+        Queue<String> output = new LinkedList<>();
+        Stack<String> ops = new Stack<>();
+
+        Map<String, Integer> prec = Map.of(
+            "+", 1,
+            "-", 1,
+            "*", 2,
+            "/", 2
+        );
+
+        for (String t : tokens) {
+            if (t.matches("-?[0-9.]+")) {
+                output.add(t);
+            } else if (prec.containsKey(t)) {
+                while (!ops.isEmpty() && prec.containsKey(ops.peek())
+                        && prec.get(ops.peek()) >= prec.get(t)) {
+                    output.add(ops.pop());
+                }
+                ops.push(t);
+            }
+        }
+        while (!ops.isEmpty()) {
+            output.add(ops.pop());
+        }
+
+        Stack<Double> stack = new Stack<>();
+        for (String t : output) {
+            if (t.matches("-?[0-9.]+")) {
+                stack.push(Double.parseDouble(t));
+            } else {
+                double b = stack.pop();
+                double a = stack.pop();
+                switch (t) {
+                    case "+": stack.push(a + b); break;
+                    case "-": stack.push(a - b); break;
+                    case "*": stack.push(a * b); break;
+                    case "/": stack.push(a / b); break;
+                }
+            }
+        }
+        return stack.pop();
     }
 }
-

src/Base.java

@@ -20,6 +20,9 @@ public abstract class Base {
     private final int height;
     private final String title;
 
+    // 🔹 keep a reference so getById works
+    protected Scene scene;
+
     public Base(String title, int width, int height) {
         this.title = title;
         this.width = width;
@@ -39,8 +42,8 @@ public abstract class Base {
     }
 
     public abstract void initUi();
-
     protected abstract void on_button_click(String label);
+    protected abstract void on_key_press(javafx.scene.input.KeyEvent event);
 
     @FXML
     protected void button_click(MouseEvent e) {
@@ -49,7 +52,15 @@ public abstract class Base {
         }
     }
 
-    protected void loadUi(String fxmlPath) {
+    protected void addKeyListener() {
+        if (scene == null) {
+            throw new IllegalStateException("Scene not loaded yet");
+        }
+        scene.setOnKeyPressed(this::on_key_press);
+    }
+
+
+    protected void loadUi(String fxmlPath, Runnable onLoaded) {
         SwingUtilities.invokeLater(() -> {
             try {
                 String resolvedPath;
@@ -66,17 +77,37 @@ public abstract class Base {
                     throw new IllegalStateException("FXML not found: " + resolvedPath);
                 }
 
-                FXMLLoader loader = new FXMLLoader(url);
-                loader.setController(this);
-                Parent root = loader.load();
-
                 javafx.application.Platform.runLater(() -> {
-                    Scene scene = new Scene(root, width, height);
+                    try {
-                    fxPanel.setScene(scene);
+                        FXMLLoader loader = new FXMLLoader(url);
+                        loader.setController(this);
+                        Parent root = loader.load();
+
+                        this.scene = new Scene(root, width, height);
+                        fxPanel.setScene(this.scene);
+                        frame.setResizable(false);
+                        if (onLoaded != null) onLoaded.run();
+                        addKeyListener();
+                    } catch (IOException e) {
+                        e.printStackTrace();
+                    }
                 });
-            } catch (IOException e) {
+            } catch (Exception e) {
                 e.printStackTrace();
             }
         });
     }
+
+    @SuppressWarnings("unchecked")
+    protected <T extends javafx.scene.Node> T getById(String id) {
+        if (this.scene == null) {
+            throw new IllegalStateException("Scene not loaded yet");
+        }
+        T node = (T) this.scene.lookup("#" + id);
+        if (node == null) {
+            throw new IllegalArgumentException("No node with id '" + id + "' found");
+        }
+        return node;
+    }
 }
+