package com.mathlearning.model;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public abstract class AbstractQuestionGenerator implements QuestionGenerator {

  @Override
  public List<Question> generateQuestions(String level, int count) {
    List<Question> questions = new ArrayList<>();
    Set<String> questionTexts = new HashSet<>();

    for (int i = 0; i < count; i++) {
      Question question = generateUniqueQuestion(level, i, questionTexts);
      if (question != null) {
        questions.add(question);
      }
    }

    return questions;
  }

  private Question generateUniqueQuestion(String level, int index, Set<String> questionTexts) {
    Question question;
    int attempt = 0;
    do {
      question = generateQuestion(level, index);
      attempt++;
    } while (question != null && questionTexts.contains(question.getQuestionText()) && attempt < 10);

    if (question != null) {
      questionTexts.add(question.getQuestionText());
    }

    return question;
  }

  protected abstract Question generateQuestion(String level, int index);
}