Confirm Password UI implemented.

src/main/java/org/to/telegramfinalproject/UI/CheckPasswordController.java

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+package org.to.telegramfinalproject.UI;
+
+import javafx.application.Platform;
+import javafx.fxml.FXML;
+import javafx.scene.control.*;
+import javafx.scene.image.Image;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.Pane;
+import javafx.scene.layout.VBox;
+
+public class CheckPasswordController {
+
+    @FXML private VBox checkPasswordCard;
+    @FXML private Pane overlayBackground;
+    @FXML private Button backButton;
+    @FXML private Button closeButton;
+    @FXML private Button cancelButton;
+    @FXML private Button confirmButton;
+    @FXML private PasswordField passwordField;
+    @FXML private TextField visiblePasswordField;
+    @FXML private Button toggleVisibilityBtn;
+    @FXML private Label passwordLabel;
+
+    private boolean passwordVisible = false;
+
+
+    @FXML
+    public void initialize() {
+        // Set back button icon
+        ImageView backIcon = new ImageView(
+                new Image(getClass().getResourceAsStream("/org/to/telegramfinalproject/Icons/back_button_dark.png"))
+        );
+        backIcon.setFitWidth(18);
+        backIcon.setFitHeight(18);
+        backButton.setGraphic(backIcon);
+
+        cancelButton.setOnAction(e ->
+                MainController.getInstance().closeOverlay(checkPasswordCard.getParent())
+        );
+
+        closeButton.setOnAction(e ->
+                MainController.getInstance().closeOverlay(checkPasswordCard.getParent())
+        );
+
+        backButton.setOnAction(e ->
+                MainController.getInstance().goBack(checkPasswordCard)
+        );
+
+        overlayBackground.setOnMouseClicked(e ->
+                MainController.getInstance().closeOverlay(checkPasswordCard.getParent())
+        );
+
+        confirmButton.setOnAction(e -> validatePassword());
+
+        // Reset error state when user starts typing again
+        passwordField.textProperty().addListener((obs, oldVal, newVal) -> {
+            if (!newVal.trim().isEmpty()) {
+                passwordField.getStyleClass().remove("error");
+                passwordLabel.getStyleClass().remove("error");
+            }
+        });
+
+        // Reset error state when user starts typing again
+        visiblePasswordField.textProperty().addListener((obs, oldVal, newVal) -> {
+            if (!newVal.trim().isEmpty()) {
+                visiblePasswordField.getStyleClass().remove("error");
+                passwordLabel.getStyleClass().remove("error");
+            }
+        });
+
+        // Auto_focus password field when overlay opens
+        Platform.runLater(() -> passwordField.requestFocus());
+
+        // Keep fields in sync
+        visiblePasswordField.textProperty().bindBidirectional(passwordField.textProperty());
+
+        // Toggle button action
+        toggleVisibilityBtn.setOnAction(e -> togglePasswordVisibility());
+
+        // Register scene for ThemeManager → stylesheet swap will handle colors/icons
+        Platform.runLater(() -> {
+            if (checkPasswordCard.getScene() != null) {
+                ThemeManager.getInstance().registerScene(checkPasswordCard.getScene());
+            }
+        });
+
+        // Listener for theme change
+        ThemeManager.getInstance().darkModeProperty().addListener((obs, oldVal, newVal) -> {
+            updateBackIcon(newVal);
+        });
+
+        // Set initial state
+        updateBackIcon(ThemeManager.getInstance().isDarkMode());
+    }
+
+    private void validatePassword() {
+        String entered = passwordField.getText().trim();
+        String correct = "12345"; // demo only
+
+        if (entered.equals(correct)) {
+            // Success → reset error styles
+            passwordField.getStyleClass().remove("error");
+            visiblePasswordField.getStyleClass().remove("error");
+            passwordLabel.getStyleClass().remove("error");
+
+            // TODO: go to change credentials scene
+            System.out.println("Password OK → go to next scene");
+            // MainController.getInstance().showOverlay("/org/to/telegramfinalproject/Fxml/change_credentials.fxml");
+
+        } else {
+            // Error → add error styles
+            if (!passwordField.getStyleClass().contains("error"))
+                passwordField.getStyleClass().add("error");
+
+            if (!visiblePasswordField.getStyleClass().contains("error"))
+                visiblePasswordField.getStyleClass().add("error");
+
+            if (!passwordLabel.getStyleClass().contains("error"))
+                passwordLabel.getStyleClass().add("error");
+        }
+    }
+
+    private void togglePasswordVisibility() {
+        passwordVisible = !passwordVisible;
+
+        visiblePasswordField.setVisible(passwordVisible);
+        visiblePasswordField.setManaged(passwordVisible);
+
+        passwordField.setVisible(!passwordVisible);
+        passwordField.setManaged(!passwordVisible);
+
+        toggleVisibilityBtn.setText(passwordVisible ? "👁" : "👁");
+    }
+
+    private void updateBackIcon(boolean darkMode) {
+        String iconPath = darkMode
+                ? "/org/to/telegramfinalproject/Icons/back_button_light.png"
+                : "/org/to/telegramfinalproject/Icons/back_button_dark.png";
+
+        ImageView icon = new ImageView(new Image(getClass().getResourceAsStream(iconPath)));
+        icon.setFitWidth(16);
+        icon.setFitHeight(16);
+        backButton.setGraphic(icon);
+    }
+}

src/main/resources/org/to/telegramfinalproject/Fxml/check_password.fxml

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+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.layout.*?>
+<?import javafx.scene.control.*?>
+<?import javafx.scene.image.ImageView?>
+<?import javafx.geometry.Insets?>
+
+<StackPane fx:id="overlayRoot" xmlns:fx="http://javafx.com/fxml"
+           fx:controller="org.to.telegramfinalproject.UI.CheckPasswordController"
+           styleClass="overlay-root">
+
+    <!-- Dimmed background -->
+    <Pane fx:id="overlayBackground" styleClass="overlay-background"/>
+
+    <!-- Password card -->
+    <VBox fx:id="checkPasswordCard"
+          styleClass="privacy-card"
+          spacing="16"
+          alignment="CENTER"
+          prefWidth="350" maxWidth="350"
+          prefHeight="200" maxHeight="200">
+
+        <!-- ===== Header ===== -->
+        <HBox alignment="CENTER_LEFT" spacing="10" styleClass="privacy-header">
+            <!-- Back -->
+            <Button fx:id="backButton" styleClass="icon-button"/>
+            <Label text="Confirm Password" styleClass="privacy-title"/>
+            <Pane HBox.hgrow="ALWAYS"/>
+            <!-- Close -->
+            <Button fx:id="closeButton" styleClass="icon-button" text="✕"/>
+        </HBox>
+
+        <Separator/>
+
+        <!-- ===== Form ===== -->
+        <VBox spacing="10" alignment="CENTER_LEFT" styleClass="privacy-form">
+            <Label fx:id="passwordLabel" text="Enter your current password"
+                   styleClass="password-label"/>
+            <HBox alignment="CENTER_LEFT" spacing="4" styleClass="privacy-item">
+                <PasswordField fx:id="passwordField"
+                               promptText="Current password"
+                               styleClass="privacy-input"
+                               HBox.hgrow="ALWAYS"/>
+                <TextField fx:id="visiblePasswordField"
+                           promptText="Current password"
+                           styleClass="privacy-input"
+                           visible="false"
+                           managed="false"
+                           HBox.hgrow="ALWAYS"/>
+                <Button fx:id="toggleVisibilityBtn"
+                        text="👁"
+                        styleClass="toggle-visibility-btn"/>
+            </HBox>
+        </VBox>
+
+        <!-- ===== Actions ===== -->
+        <HBox alignment="CENTER_RIGHT" spacing="10">
+            <Button fx:id="cancelButton" text="Cancel" styleClass="footer-button"/>
+            <Button fx:id="confirmButton" text="Next" styleClass="action-button"/>
+        </HBox>
+    </VBox>
+</StackPane>