import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.Scanner;

public class QuestionsHandler {

    private ArrayList<Question> questions;
    private Comparator comparator;



    public QuestionsHandler() {
        this.questions = new ArrayList<Question>();
        this.comparator = null;
    }

    public void setComparator(Comparator comparator) {
        this.comparator = comparator;
    }

    public Comparator getComparator() {
        return comparator;
    }

    public void setQuestions(ArrayList<Question> questions){
        this.questions = questions;
    }

    public ArrayList<Question> getQuestions() {
        return questions;
    }

    public void loadQuestions(char[] password, String finput, boolean skipDuplicates) throws Exception {
        if (skipDuplicates && (comparator == null)) throw (new NullPointerException());

        //

        BufferedInputStream fin = new BufferedInputStream(new FileInputStream(finput));
        byte[] ciphertext = new byte[fin.available()];
        fin.read(ciphertext);
        fin.close();

        byte[] cleartext = DataCipher.decryptData(ciphertext, password);

        QuestionBuilder builder = new QuestionBuilder();
        Scanner scanner = new Scanner(new String(cleartext));
        while (scanner.hasNextLine()) {
            String[] data = scanner.nextLine().split(";;");
            ArrayList<Answer> answers = new ArrayList<Answer>();

            builder.setContent(data[0]);
            builder.setSubject(data[1]);
            builder.setCategory(data[2]);
            builder.setDifficultyLevel(Integer.parseInt(data[3]));
            builder.setMultipleChoice(Boolean.parseBoolean(data[4]));

            String temp = null;
            for (int i = 0; i < Integer.parseInt(data[5]); i++) {
                temp = data[(5 + 1) + i];
                if (temp.startsWith("%%")) {
                    answers.add(new Answer(temp.substring(2), Boolean.TRUE, Boolean.FALSE));
                } else {
                    answers.add(new Answer(temp, Boolean.FALSE, Boolean.FALSE));
                }
            }

            builder.setAnswers(answers);
            builder.setReference(data[data.length - 2]);
            builder.setComment(data[data.length - 1]);

            Question q1 = builder.build();
            if (skipDuplicates) {
                boolean flag = false;
                for (Question q2: questions) {
                    if (comparator.compare(q1, q2) == 0) {
                        flag = true;
                        break;
                    }
                }
                if (!flag) questions.add(q1);
            } else {
                questions.add(q1);
            }
        }
    }

    public void saveQuestions(char[] password, String foutput) throws Exception {
        BufferedOutputStream fout = new BufferedOutputStream(new FileOutputStream(foutput));
        StringBuilder sb = new StringBuilder();

        for (Question q: questions) {
            sb.append(q.getContent()).append(";;");
            sb.append(q.getSubject()).append(";;");
            sb.append(q.getCategory()).append(";;");
            sb.append(String.valueOf(q.getDifficultyLevel())).append(";;");
            sb.append(String.valueOf(q.isMultipleChoice())).append(";;");
            sb.append(String.valueOf(q.getAnswers().size())).append(";;");

            for(Answer answer: q.getAnswers()) {
                if(answer.isCorrect()) {
                    sb.append("%%").append(String.format("%s;;", answer.getContent()));
                } else {
                    sb.append(String.format("%s;;", answer.getContent()));
                }
            }

            sb.append(q.getReference()).append(";;");
            sb.append(q.getComment()).append(";;");
            sb.append("\n");
        }

        fout.write(DataCipher.encrypData((new String(sb)).getBytes(), password));
        fout.flush();
        fout.close();
    }

    public void removeDuplicates() {
        if (comparator == null) throw (new NullPointerException());

        //

        ArrayList<Question> temp = new ArrayList<Question>();
        for (Question q1: questions) {
            boolean flag = false;
            for (Question q2: temp) {
                if (comparator.compare(q1, q2) == 0) {
                    flag = true;
                    break;
                }
            }
            if (!flag) temp.add(q1);
        }
        this.questions = temp;
    }

    public void addQuestion(Question q) {
        questions.add(q);
    }

    public void removeQuestion(Question q1) {
        if (comparator == null) throw (new NullPointerException());

        //

        ArrayList<Question> temp = new ArrayList<Question>();
        for (Question q2: questions) {
            if (comparator.compare(q1, q2) != 0) temp.add(q2);
        }
        this.questions = temp;
    }

}