let currentCard = null;
let attempts = 0;
let stats = { points: 0, total: 0 };

document.addEventListener('DOMContentLoaded', loadLessons);

function loadLessons() {
    fetch('/api/lessons')
        .then(res => res.json())
        .then(lessons => {
            const list = document.getElementById('lesson-list');
            list.innerHTML = '';
            lessons.forEach(l => {
                const div = document.createElement('div');
                div.className = 'lesson-item';
                div.innerHTML = `
                    <input type="checkbox" id="l-${l}" value="${l}" onchange="updateStartBtn()">
                    <label for="l-${l}">${l}</label>
                `;
                list.appendChild(div);
            });
        });
}

function updateStartBtn() {
    const checked = document.querySelectorAll('#lesson-list input:checked');
    document.getElementById('btn-start').disabled = (checked.length === 0);
}

function startQuiz() {
    stats = { points: 0, total: 0 };
    updateStats();
    document.getElementById('setup-screen').style.display = 'none';
    document.getElementById('quiz-screen').style.display = 'flex';
    nextQuestion();
}

function stopQuiz() {
    document.getElementById('quiz-screen').style.display = 'none';
    document.getElementById('setup-screen').style.display = 'block';
}

function nextQuestion() {
    const btn = document.getElementById('btn-action');
    btn.innerText = "Prüfen";
    btn.onclick = checkAnswer;
    btn.className = "action-btn primary";
    
    document.getElementById('feedback').innerText = '';
    
    const lids = Array.from(document.querySelectorAll('#lesson-list input:checked')).map(cb => cb.value);
    const mid = document.getElementById('opt-middle').checked;

    fetch('/api/question', {
        method: 'POST',
        headers: {'Content-Type': 'application/json'},
        body: JSON.stringify({ lessons: lids, askMiddle: mid })
    })
    .then(res => res.json())
    .then(card => {
        if(card.error) { alert(card.error); stopQuiz(); return; }
        currentCard = card;
        attempts = 0;
        renderCard(card);
    });
}

function renderCard(card) {
    document.getElementById('latin-text').innerText = card.latin;
    document.getElementById('hint-text').innerText = card.hint;
    
    const container = document.getElementById('inputs-container');
    container.innerHTML = '';
    
    if (card.middle_req) {
        const row = document.createElement('div');
        row.className = 'input-row';
        row.innerHTML = `
            <span class="lbl">Form:</span>
            <input type="text" class="quiz-input" data-type="middle" data-correct="${card.middle_correct}" placeholder="z.B. f, Gen">
        `;
        container.appendChild(row);
    }
    
    card.german_correct.forEach(ans => {
        const row = document.createElement('div');
        row.className = 'input-row';
        row.innerHTML = `
            <span class="lbl">Dt:</span>
            <input type="text" class="quiz-input" data-type="german" data-correct="${ans}" placeholder="Bedeutung">
        `;
        container.appendChild(row);
    });
    
    const first = container.querySelector('input');
    if(first) first.focus();
}

function checkAnswer() {
    const inputs = document.querySelectorAll('.quiz-input');
    const payload = [];
    inputs.forEach(i => {
        payload.push({ 
            value: i.value, 
            correct: i.dataset.correct,
            type: i.dataset.type || 'german'
        });
    });
    
    attempts++;
    
    fetch('/api/check', {
        method: 'POST',
        headers: {'Content-Type': 'application/json'},
        body: JSON.stringify({ inputs: payload, attempt: attempts })
    })
    .then(res => res.json())
    .then(res => {
        const fb = document.getElementById('feedback');
        let globalMsg = "";
        
        res.results.forEach((r, idx) => {
            const el = inputs[idx];
            el.classList.remove('wrong', 'correct', 'typo', 'incomplete');
            
            if (r.status === 'correct') {
                el.classList.add('correct');
            } else if (r.status === 'typo') {
                el.classList.add('typo');
            } else if (r.status === 'incomplete') {
                el.classList.add('incomplete');
                globalMsg = r.msg; 
            } else {
                el.classList.add('wrong');
            }
        });

        if (res.all_correct) {
            fb.innerText = "Alles richtig!";
            fb.style.color = "green";
            stats.points += res.score; 
            finishTurn();
        } else {
            if (res.has_incomplete) {
                fb.innerText = globalMsg || "Unvollständig.";
                fb.style.color = "#d39e00";
            } else {
                if (attempts >= 3) {
                    fb.innerText = "Leider nicht geschafft. Lösungen eingesetzt.";
                    fb.style.color = "red";
                    inputs.forEach(i => i.value = i.dataset.correct);
                    finishTurn();
                } else {
                    fb.innerText = `Fehler. Versuch ${attempts}/3`;
                    fb.style.color = "orange";
                }
            }
        }
    });
}

function finishTurn() {
    stats.total++;
    updateStats();
    const btn = document.getElementById('btn-action');
    btn.innerText = "Weiter";
    btn.onclick = nextQuestion;
    btn.focus();
}

function updateStats() {
    let p = 0;
    if (stats.total > 0) p = Math.round((stats.points / stats.total) * 100);
    document.getElementById('progress-bar').style.width = `${p}%`;
    document.getElementById('stats-text').innerText = `${p}% (${stats.points.toFixed(1)}/${stats.total})`;
}

document.addEventListener('keypress', (e) => {
    if (e.key === 'Enter') document.getElementById('btn-action').click();
});