package com.mathlearning.model;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class Paper implements Serializable {
    private static final long serialVersionUID = 1L;
    
    private List<Question> questions;
    private int currentQuestionIndex;
    private String level;
    
    public Paper(String level) {
        this.questions = new ArrayList<>();
        this.currentQuestionIndex = 0;
        this.level = level;
    }
    
    public void addQuestion(Question question) {
        questions.add(question);
    }
    
    public Question getCurrentQuestion() {
        if (currentQuestionIndex < questions.size()) {
            return questions.get(currentQuestionIndex);
        }
        return null;
    }
    
    public boolean hasNextQuestion() {
        return currentQuestionIndex < questions.size() - 1;
    }
    
    public void nextQuestion() {
        if (hasNextQuestion()) {
            currentQuestionIndex++;
        }
    }
    
    public boolean hasPreviousQuestion() {
        return currentQuestionIndex > 0;
    }
    
    public void previousQuestion() {
        if (hasPreviousQuestion()) {
            currentQuestionIndex--;
        }
    }
    
    public int getTotalQuestions() {
        return questions.size();
    }
    
    public int getCurrentQuestionNumber() {
        return currentQuestionIndex + 1;
    }
    
    public int calculateScore() {
        int correctCount = 0;
        for (Question q : questions) {
            if (q.isCorrect()) {
                correctCount++;
            }
        }
        return (int) ((correctCount * 100.0) / questions.size());
    }
    
    public String getLevel() { return level; }
    public void setLevel(String level) { this.level = level; }
    
    public List<Question> getQuestions() { return questions; }
}