package com.personalproject.ui.views;

import com.personalproject.controller.MathLearningController;
import com.personalproject.model.ExamSession;
import com.personalproject.model.QuizQuestion;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;

/**
 * 提供答题界面以及题目与选项的呈现.
 */
public class ExamView extends BorderPane {

  private final Stage primaryStage;
  private final MathLearningController controller;
  private final ExamSession examSession;
  private Label questionNumberLabel;
  private Label questionTextLabel;
  private ToggleGroup answerToggleGroup;
  private VBox optionsBox;
  private Button nextButton;
  private Button previousButton;
  private Button finishButton;
  private HBox buttonBox;

  /**
   * ExamView 的构造函数.
   *
   * @param primaryStage 应用程序的主舞台
   * @param controller   数学学习控制器
   * @param examSession  当前的考试会话
   */
  public ExamView(Stage primaryStage, MathLearningController controller, ExamSession examSession) {
    this.primaryStage = primaryStage;
    this.controller = controller;
    this.examSession = examSession;
    initializeUi();
  }

  /**
   * 初始化界面组件.
   */
  private void initializeUi() {
    // 创建主布局
    VBox mainLayout = new VBox(20);
    mainLayout.setAlignment(Pos.CENTER);
    mainLayout.setPadding(new Insets(20));

    // 题号
    questionNumberLabel = new Label();
    questionNumberLabel.setFont(Font.font("System", FontWeight.BOLD, 16));

    // 题目文本
    questionTextLabel = new Label();
    questionTextLabel.setWrapText(true);
    questionTextLabel.setFont(Font.font("System", FontWeight.NORMAL, 14));
    questionTextLabel.setMaxWidth(500);

    // 选项容器
    optionsBox = new VBox(10);
    optionsBox.setPadding(new Insets(10));
    answerToggleGroup = new ToggleGroup();

    // 按钮区域
    buttonBox = new HBox(15);
    buttonBox.setAlignment(Pos.CENTER);

    previousButton = new Button("上一题");
    nextButton = new Button("下一题");
    finishButton = new Button("完成考试");

    // 设置按钮尺寸
    previousButton.setPrefSize(100, 35);
    nextButton.setPrefSize(100, 35);
    finishButton.setPrefSize(120, 35);

    buttonBox.getChildren().addAll(previousButton, nextButton, finishButton);

    // 将组件添加到主布局
    mainLayout.getChildren().addAll(questionNumberLabel, questionTextLabel, optionsBox, buttonBox);

    // 将主布局置于边界面板中央
    setCenter(mainLayout);

    // 加载第一题
    loadCurrentQuestion();

    // 添加事件处理器
    addEventHandlers();
  }

  /**
   * 将当前题目加载到界面.
   */
  private void loadCurrentQuestion() {
    try {
      // 在加载下一题之前检查考试是否已完成
      if (examSession.isComplete()) {
        // 如果考试已完成，则启用“完成考试”按钮
        updateButtonStates();
        return;
      }

      QuizQuestion currentQuestion = examSession.getCurrentQuestion();
      int currentIndex = examSession.getCurrentQuestionIndex();

      if (currentQuestion == null) {
        showAlert(Alert.AlertType.ERROR, "错误", "当前题目为空，请重新开始考试");
        return;
      }

      // 更新题号与题目文本
      questionNumberLabel.setText("第 " + (currentIndex + 1) + " 题");
      questionTextLabel.setText(currentQuestion.getQuestionText());

      // 清空上一题的选项
      answerToggleGroup.selectToggle(null);
      answerToggleGroup.getToggles().clear();
      optionsBox.getChildren().clear();

      // 创建新的选项组件
      for (int i = 0; i < currentQuestion.getOptions().size(); i++) {
        String option = currentQuestion.getOptions().get(i);
        RadioButton optionButton = new RadioButton((i + 1) + ". " + option);
        optionButton.setToggleGroup(answerToggleGroup);
        optionButton.setUserData(i); // 存储选项索引

        // 如果该题已有答案则自动选中
        if (examSession.hasAnswered(currentIndex)
            && examSession.getUserAnswer(currentIndex) == i) {
          optionButton.setSelected(true);
        }

        optionsBox.getChildren().add(optionButton);
      }

      // 更新按钮状态
      updateButtonStates();
    } catch (Exception e) {
      showAlert(Alert.AlertType.ERROR, "错误", "加载题目时发生错误: " + e.getMessage());
    }
  }

  /**
   * 根据当前位置更新导航按钮的状态.
   */
  private void updateButtonStates() {
    try {
      int currentIndex = examSession.getCurrentQuestionIndex();
      int totalQuestions = examSession.getTotalQuestions();

      // 处理潜在极端情况
      if (totalQuestions <= 0) {
        // 如果没有题目，则禁用所有导航按钮
        previousButton.setDisable(true);
        nextButton.setDisable(true);
        finishButton.setDisable(false); // 仍允许完成考试
        return;
      }

      // “上一题”按钮状态
      previousButton.setDisable(currentIndex < 0 || currentIndex == 0);

      // “下一题”按钮状态
      nextButton.setDisable(currentIndex < 0 || currentIndex >= totalQuestions - 1);

      // “完成考试”按钮状态——在考试完成或到达最后一题时启用
      boolean isExamComplete = examSession.isComplete();
      boolean isAtLastQuestion = (currentIndex >= totalQuestions - 1);
      finishButton.setDisable(!(isExamComplete || isAtLastQuestion));
    } catch (Exception e) {
      // 若出现异常，禁用导航按钮以避免进一步问题
      previousButton.setDisable(true);
      nextButton.setDisable(true);
      finishButton.setDisable(false); // 仍允许完成考试
      showAlert(Alert.AlertType.ERROR, "错误", "更新按钮状态时发生错误: " + e.getMessage());
    }
  }

  /**
   * 为界面组件添加事件处理器.
   */
  private void addEventHandlers() {
    nextButton.setOnAction(e -> handleNextQuestion());
    previousButton.setOnAction(e -> handlePreviousQuestion());
    finishButton.setOnAction(e -> handleFinishExam());

    // 添加变更监听器，在选项被选择时保存答案
    answerToggleGroup.selectedToggleProperty().addListener((obs, oldSelection, newSelection) -> {
      if (newSelection != null) {
        int selectedIndex = (Integer) newSelection.getUserData();
        examSession.setAnswer(selectedIndex);
      }
    });
  }

  /**
   * 处理“下一题”按钮的操作.
   */
  private void handleNextQuestion() {
    try {
      if (examSession.goToNextQuestion()) {
        loadCurrentQuestion();
      } else {
        // 若无法跳转到下一题，可能已经到达末尾
        // 检查考试是否完成并据此更新按钮状态
        updateButtonStates();
      }
    } catch (Exception e) {
      showAlert(Alert.AlertType.ERROR, "错误", "导航到下一题时发生错误: " + e.getMessage());
    }
  }

  /**
   * 处理“上一题”按钮的操作.
   */
  private void handlePreviousQuestion() {
    try {
      if (examSession.goToPreviousQuestion()) {
        loadCurrentQuestion();
      } else {
        // 若无法返回上一题，可能已经位于开头
        updateButtonStates();
      }
    } catch (Exception e) {
      showAlert(Alert.AlertType.ERROR, "错误", "导航到上一题时发生错误: " + e.getMessage());
    }
  }

  /**
   * 显示提示对话框.
   *
   * @param alertType 提示类型
   * @param title     对话框标题
   * @param message   显示的消息
   */
  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();
  }

  /**
   * 处理“完成考试”按钮的操作.
   */
  private void handleFinishExam() {
    // 保存考试结果
    controller.saveExamResults(examSession);

    // 展示考试结果
    ExamResultsView resultsView = new ExamResultsView(primaryStage, controller, examSession);
    primaryStage.getScene().setRoot(resultsView);
  }
}