package com.personalproject.model;

import java.util.List;

/**
 * 表示一个带有多项选择的测验题目.
 */
public final class QuizQuestion {

  private final String questionText;
  private final List<String> options;
  private final int correctAnswerIndex;

  /**
   * 创建新的测验题目.
   *
   * @param questionText       题目文本
   * @param options            答案选项列表
   * @param correctAnswerIndex 正确答案在选项列表中的索引
   */
  public QuizQuestion(String questionText, List<String> options, int correctAnswerIndex) {
    if (questionText == null || questionText.trim().isEmpty()) {
      throw new IllegalArgumentException("Question text cannot be null or empty");
    }
    if (options == null || options.size() < 2) {
      throw new IllegalArgumentException("Options must contain at least 2 choices");
    }
    if (correctAnswerIndex < 0 || correctAnswerIndex >= options.size()) {
      throw new IllegalArgumentException("Correct answer index out of bounds");
    }

    this.questionText = questionText;
    this.options = List.copyOf(options); // 不可变副本
    this.correctAnswerIndex = correctAnswerIndex;
  }

  /**
   * 获取题目文本.
   *
   * @return 题目文本
   */
  public String getQuestionText() {
    return questionText;
  }

  /**
   * 获取答案选项列表.
   *
   * @return 不可修改的答案选项列表
   */
  public List<String> getOptions() {
    return options;
  }

  /**
   * 获取正确答案在选项列表中的索引.
   *
   * @return 正确答案的索引
   */
  public int getCorrectAnswerIndex() {
    return correctAnswerIndex;
  }

  /**
   * 检查给定的答案索引是否正确.
   *
   * @param answerIndex 用户答案的索引
   * @return 若答案正确则返回 true，否则返回 false
   */
  public boolean isAnswerCorrect(int answerIndex) {
    return answerIndex == correctAnswerIndex;
  }
}