package com.personalproject.ui.scenes;

import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;
import com.personalproject.controller.MathLearningController;
import com.personalproject.model.DifficultyLevel;
import com.personalproject.ui.scenes.LoginScene;

/**
 * Scene for handling user registration.
 */
public class RegistrationScene extends BorderPane {

  private final Stage primaryStage;
  private final MathLearningController controller;
  private TextField usernameField;
  private TextField emailField;
  private ComboBox<DifficultyLevel> difficultyComboBox;
  private Button sendCodeButton;
  private TextField registrationCodeField;
  private Button verifyCodeButton;
  private PasswordField passwordField;
  private PasswordField confirmPasswordField;
  private Button setPasswordButton;
  private Button backButton;
  private VBox registrationForm;

  /**
   * Constructor for RegistrationScene.
   *
   * @param primaryStage The main stage of the application
   * @param controller The math learning controller
   */
  public RegistrationScene(Stage primaryStage, MathLearningController controller) {
    this.primaryStage = primaryStage;
    this.controller = controller;
    initializeUI();
  }

  /**
   * Initializes the UI components.
   */
  private void initializeUI() {
    // Create the main layout
    VBox mainLayout = new VBox(15);
    mainLayout.setAlignment(Pos.CENTER);
    mainLayout.setPadding(new Insets(20));
    
    // Title
    Label titleLabel = new Label("用户注册");
    titleLabel.setFont(Font.font("System", FontWeight.BOLD, 24));
    
    // Registration Form
    registrationForm = new VBox(15);
    registrationForm.setAlignment(Pos.CENTER);
    
    // Step 1: Basic Info
    GridPane basicInfoForm = new GridPane();
    basicInfoForm.setHgap(10);
    basicInfoForm.setVgap(10);
    basicInfoForm.setAlignment(Pos.CENTER);
    
    Label usernameLabel = new Label("用户名:");
    usernameField = new TextField();
    usernameField.setPrefWidth(200);
    
    Label emailLabel = new Label("邮箱:");
    emailField = new TextField();
    emailField.setPrefWidth(200);
    
    Label difficultyLabel = new Label("默认难度:");
    difficultyComboBox = new ComboBox<>();
    difficultyComboBox.getItems().addAll(DifficultyLevel.PRIMARY, DifficultyLevel.MIDDLE, DifficultyLevel.HIGH);
    difficultyComboBox.setValue(DifficultyLevel.PRIMARY);
    difficultyComboBox.setPrefWidth(200);
    
    basicInfoForm.add(usernameLabel, 0, 0);
    basicInfoForm.add(usernameField, 1, 0);
    basicInfoForm.add(emailLabel, 0, 1);
    basicInfoForm.add(emailField, 1, 1);
    basicInfoForm.add(difficultyLabel, 0, 2);
    basicInfoForm.add(difficultyComboBox, 1, 2);
    
    sendCodeButton = new Button("发送注册码");
    sendCodeButton.setPrefWidth(120);
    
    registrationForm.getChildren().addAll(basicInfoForm, sendCodeButton);
    
    // Step 2: Verification (hidden initially)
    VBox verificationSection = new VBox(10);
    verificationSection.setAlignment(Pos.CENTER);
    verificationSection.setVisible(false);
    verificationSection.setManaged(false);
    
    Label codeLabel = new Label("注册码:");
    registrationCodeField = new TextField();
    registrationCodeField.setPrefWidth(200);
    
    verifyCodeButton = new Button("验证注册码");
    verifyCodeButton.setPrefWidth(120);
    
    verificationSection.getChildren().addAll(codeLabel, registrationCodeField, verifyCodeButton);
    registrationForm.getChildren().add(verificationSection);
    
    // Step 3: Password Setting (hidden initially)
    VBox passwordSection = new VBox(10);
    passwordSection.setAlignment(Pos.CENTER);
    passwordSection.setVisible(false);
    passwordSection.setManaged(false);
    
    Label passwordLabel = new Label("设置密码 (6-10位，包含大小写字母和数字):");
    passwordField = new PasswordField();
    passwordField.setPrefWidth(200);
    
    Label confirmPasswordLabel = new Label("确认密码:");
    confirmPasswordField = new PasswordField();
    confirmPasswordField.setPrefWidth(200);
    
    setPasswordButton = new Button("设置密码");
    setPasswordButton.setPrefWidth(120);
    
    passwordSection.getChildren().addAll(passwordLabel, passwordField, confirmPasswordLabel, 
        confirmPasswordField, setPasswordButton);
    registrationForm.getChildren().add(passwordSection);
    
    // Back button
    backButton = new Button("返回");
    backButton.setPrefWidth(100);
    
    // Add components to main layout
    mainLayout.getChildren().addAll(titleLabel, registrationForm, backButton);
    
    setCenter(mainLayout);
    
    // Add event handlers
    addEventHandlers(sendCodeButton, verificationSection, verifyCodeButton, passwordSection);
  }

  /**
   * Adds event handlers to UI components.
   */
  private void addEventHandlers(Button sendCodeButton, VBox verificationSection, 
      Button verifyCodeButton, VBox passwordSection) {
    sendCodeButton.setOnAction(e -> handleSendCode(verificationSection));
    verifyCodeButton.setOnAction(e -> handleVerifyCode(passwordSection));
    setPasswordButton.setOnAction(e -> handleSetPassword());
    backButton.setOnAction(e -> handleBack());
  }

  /**
   * Handles sending registration code.
   */
  private void handleSendCode(VBox verificationSection) {
    String username = usernameField.getText().trim();
    String email = emailField.getText().trim();
    DifficultyLevel difficultyLevel = difficultyComboBox.getValue();

    if (username.isEmpty() || email.isEmpty()) {
      showAlert(Alert.AlertType.WARNING, "警告", "请输入用户名和邮箱");
      return;
    }

    if (!controller.isValidEmail(email)) {
      showAlert(Alert.AlertType.ERROR, "邮箱格式错误", "请输入有效的邮箱地址");
      return;
    }

    // Initiate registration
    boolean success = controller.initiateRegistration(username, email, difficultyLevel);

    if (success) {
      showAlert(Alert.AlertType.INFORMATION, "注册码已发送", "注册码已发送至您的邮箱，请查收。");
      verificationSection.setVisible(true);
      verificationSection.setManaged(true);
    } else {
      showAlert(Alert.AlertType.ERROR, "注册失败", "用户名或邮箱可能已存在，请重试。");
    }
  }

  /**
   * Handles verification of registration code.
   */
  private void handleVerifyCode(VBox passwordSection) {
    String username = usernameField.getText().trim();
    String registrationCode = registrationCodeField.getText().trim();

    if (registrationCode.isEmpty()) {
      showAlert(Alert.AlertType.WARNING, "警告", "请输入注册码");
      return;
    }

    boolean verified = controller.verifyRegistrationCode(username, registrationCode);

    if (verified) {
      showAlert(Alert.AlertType.INFORMATION, "验证成功", "注册码验证成功！");
      passwordSection.setVisible(true);
      passwordSection.setManaged(true);
    } else {
      showAlert(Alert.AlertType.ERROR, "验证失败", "注册码验证失败，请检查后重试。");
    }
  }

  /**
   * Handles setting the user password.
   */
  private void handleSetPassword() {
    String username = usernameField.getText().trim();
    String password = passwordField.getText();
    String confirmPassword = confirmPasswordField.getText();

    if (password.isEmpty() || confirmPassword.isEmpty()) {
      showAlert(Alert.AlertType.WARNING, "警告", "请输入并确认密码");
      return;
    }

    if (!password.equals(confirmPassword)) {
      showAlert(Alert.AlertType.ERROR, "密码不匹配", "两次输入的密码不一致");
      return;
    }

    if (!controller.isValidPassword(password)) {
      showAlert(Alert.AlertType.ERROR, "密码不符合要求", 
          "密码长度必须为6-10位，且包含大小写字母和数字");
      return;
    }

    boolean success = controller.setPassword(username, password);

    if (success) {
      showAlert(Alert.AlertType.INFORMATION, "注册成功", "注册成功！请登录。");
      handleBack(); // Go back to login screen
    } else {
      showAlert(Alert.AlertType.ERROR, "设置密码失败", "设置密码失败，请重试。");
    }
  }

  /**
   * Handles the back button action.
   */
  private void handleBack() {
    LoginScene loginScene = new LoginScene(primaryStage, controller);
    primaryStage.getScene().setRoot(loginScene);
  }

  /**
   * Shows an alert dialog.
   *
   * @param alertType Type of alert
   * @param title Title of the alert
   * @param message Message to display
   */
  private void showAlert(Alert.AlertType alertType, String title, String message) {
    Alert alert = new Alert(alertType);
    alert.setTitle(title);
    alert.setHeaderText(null);
    alert.setContentText(message);
    alert.showAndWait();
  }
}