document.addEventListener('DOMContentLoaded', async () => {
    const body = document.body;
    const topic = body.dataset.topic;
    const currentLessonId = parseInt(body.dataset.lessonId, 10);

    if (!topic) return;

    // --- Pobieranie danych o lekcjach ---
    const response = await fetch('lekcje.json');
    const allTopics = await response.json();
    const topicData = allTopics[topic];
    const lessons = topicData.lessons;
    const totalLessons = lessons.length;

    // --- Inicjalizacja Dropdown Menu ---
    const dropdownContent = document.querySelector('.dropdown-content');
    const dropdownButton = document.querySelector('.dropdown-button');

    lessons.forEach(lesson => {
        const a = document.createElement('a');
        a.href = lesson.url;
        a.textContent = `Lekcja ${lesson.id}: ${lesson.title}`;
        if (lesson.id === currentLessonId) {
            a.classList.add('active');
        }
        dropdownContent.appendChild(a);
    });

    dropdownButton.addEventListener('click', (e) => {
        e.stopPropagation();
        dropdownContent.classList.toggle('show');
    });

    document.addEventListener('click', (e) => {
        if (!e.target.matches('.dropdown-button')) {
            if (dropdownContent.classList.contains('show')) {
                dropdownContent.classList.remove('show');
            }
        }
    });

    // --- Zarządzanie postępem ---
    const progressKey = `progress_${topic}`;
    let progress = JSON.parse(localStorage.getItem(progressKey)) || [];

    const progressBar = document.querySelector('.progress');
    const progressLabel = document.querySelector('.progress-label');

    function updateProgress() {
        const completedCount = progress.length;
        const progressPercentage = (completedCount / totalLessons) * 100;

        if (progressBar) progressBar.style.width = `${progressPercentage}%`;
        if (progressLabel) progressLabel.textContent = `Postęp: ${completedCount}/${totalLessons}`;
    }

    // --- Interaktywne zadania ---
    const interactiveInputs = document.querySelectorAll('.interactive-input');
    interactiveInputs.forEach(input => {
        input.addEventListener('change', () => {
            const correctAnswer = input.dataset.answer;
            const feedbackSpan = input.nextElementSibling;
            if (input.value === correctAnswer) {
                feedbackSpan.textContent = '✅ Dobrze!';
                feedbackSpan.style.color = 'green';
                input.style.borderColor = 'green';

                // Sprawdź, czy wszystkie zadania na stronie są rozwiązane
                const allCorrect = Array.from(document.querySelectorAll('.interactive-input')).every(i => i.style.borderColor === 'green');

                // Zapisz postęp, jeśli wszystkie zadania są poprawne
                if (allCorrect && !progress.includes(currentLessonId)) {
                    progress.push(currentLessonId);
                    localStorage.setItem(progressKey, JSON.stringify(progress));
                    updateProgress();
                }
            } else {
                feedbackSpan.textContent = '❌ Spróbuj jeszcze raz.';
                feedbackSpan.style.color = 'red';
                input.style.borderColor = 'red';
            }
        });
    });

    // --- Ćwiczenie "Start i doskocz" ---
    const jumpExercise = document.querySelector('#exercise2');
    if (jumpExercise) {
        const jumpButtons = jumpExercise.querySelectorAll('.jump-btn');
        const jumpFeedback = jumpExercise.querySelector('.jump-feedback');
        let jumpCounter = 5;
        let jumpsMade = 0;

        jumpButtons.forEach(button => {
            button.addEventListener('click', () => {
                if (button.classList.contains('activated')) return;

                jumpsMade++;
                jumpCounter++;
                button.classList.add('activated');
                button.textContent = jumpCounter;

                let feedbackText = "Start: 5";
                for (let i = 1; i <= jumpsMade; i++) {
                    feedbackText += ` ↷ ${5 + i}`;
                }
                jumpFeedback.textContent = feedbackText;

                // Po ostatnim skoku, wypełnij pole odpowiedzi
                if (jumpsMade === jumpButtons.length) {
                    const targetInput = jumpExercise.querySelector('.interactive-input');
                    targetInput.value = jumpCounter;
                    // Wywołaj zdarzenie 'change', aby sprawdzić odpowiedź i zapisać postęp
                    targetInput.dispatchEvent(new Event('change'));
                }
            });
        });
    }

    // --- Losowe ćwiczenie "Start i doskocz" ---
    const randomExerciseContainer = document.getElementById('random-exercise-container');
    const retryButton = document.getElementById('retry-random-exercise');

    function generateRandomExercise() {
        const num1 = Math.floor(Math.random() * 8) + 2; // 2-9
        const num2 = Math.floor(Math.random() * 8) + 2; // 2-9
        const startNum = Math.max(num1, num2);
        const jumpCount = Math.min(num1, num2);
        const answer = startNum + jumpCount;

        let jumpsHTML = '';
        for (let i = 0; i < jumpCount; i++) {
            jumpsHTML += `<button class="jump-btn" data-value="${startNum + i + 1}">+1</button>`;
        }

        randomExerciseContainer.innerHTML = `
            <div class="interactive-exercise" id="random-exercise">
                <h4>Ćwiczenie losowe</h4>
                <p>Mamy <strong>${startNum}</strong>. Chcemy dołożyć <strong>${jumpCount}</strong>.</p>
                <div class="start-and-jump">
                    <div class="start-number">${startNum}</div>
                    <div class="jumps">${jumpsHTML}</div>
                </div>
                <p>Klikaj przyciski "+1", żeby "doskoczyć" do wyniku. Jaki będzie wynik?</p>
                <div class="interactive-example">
                    <span>${startNum} + ${jumpCount} = </span>
                    <input type="number" class="interactive-input" data-answer="${answer}">
                    <span class="feedback"></span>
                </div>
                <div class="jump-feedback">
                    Start: ${startNum}...
                </div>
            </div>
        `;
        setupRandomExerciseListeners();
        setupInteractiveInputs(); // Ponownie podłączamy listenery do nowo dodanych inputów
    }

    function setupRandomExerciseListeners() {
        const exercise = document.getElementById('random-exercise');
        if (!exercise) return;

        const jumpButtons = exercise.querySelectorAll('.jump-btn');
        const jumpFeedback = exercise.querySelector('.jump-feedback');
        const startNum = parseInt(exercise.querySelector('.start-number').textContent, 10);
        let jumpCounter = startNum;
        let jumpsMade = 0;

        jumpButtons.forEach(button => {
            button.addEventListener('click', () => {
                if (button.classList.contains('activated')) return;

                jumpsMade++;
                jumpCounter++;
                button.classList.add('activated');
                button.textContent = jumpCounter;

                let feedbackText = `Start: ${startNum}`;
                for (let i = 1; i <= jumpsMade; i++) {
                    feedbackText += ` ↷ ${startNum + i}`;
                }
                jumpFeedback.textContent = feedbackText;

                if (jumpsMade === jumpButtons.length) {
                    const targetInput = exercise.querySelector('.interactive-input');
                    targetInput.value = jumpCounter;
                    targetInput.dispatchEvent(new Event('change'));
                }
            });
        });
    }

    function setupInteractiveInputs() {
        const allInputs = document.querySelectorAll('.interactive-input');
        allInputs.forEach(input => {
            // Usuń stare listenery, aby uniknąć duplikacji
            const newInput = input.cloneNode(true);
            input.parentNode.replaceChild(newInput, input);

            newInput.addEventListener('change', () => {
                const correctAnswer = newInput.dataset.answer;
                const feedbackSpan = newInput.nextElementSibling;
                if (newInput.value === correctAnswer) {
                    feedbackSpan.textContent = '✅ Dobrze!';
                    feedbackSpan.style.color = 'green';
                    newInput.style.borderColor = 'green';

                    const allCorrect = Array.from(document.querySelectorAll('.interactive-input')).every(i => i.style.borderColor === 'green');

                    if (allCorrect && !progress.includes(currentLessonId)) {
                        progress.push(currentLessonId);
                        localStorage.setItem(progressKey, JSON.stringify(progress));
                        updateProgress();
                    }
                } else {
                    feedbackSpan.textContent = '❌ Spróbuj jeszcze raz.';
                    feedbackSpan.style.color = 'red';
                    newInput.style.borderColor = 'red';
                }
            });
        });
    }


    if (randomExerciseContainer) {
        generateRandomExercise();
        retryButton.addEventListener('click', generateRandomExercise);
    } else {
        setupInteractiveInputs();
    }


    // Inicjalizacja paska postępu przy ładowaniu strony
    updateProgress();
});