let currentSessionId = null;
let currentQuestionNumber = 1;
let totalQuestions = 10;
let currentScore = 0;
let attemptsUsed = 0;
const maxAttempts = 3;
let selectedDifficulty = "all";
let lastQuestionData = null;
let timerStartTime = null;
let timerInterval = null;
let elapsedSeconds = 0;

const UI_TEXT = {
    de: {
        pageTitle: "✨ Magisches Hogwarts-Escape-Quiz ✨",
        pageSubtitle: "10 knifflige Rätsel aus der Zauberwelt warten auf dich",
        envelopeLetter: "Hogwarts-Schule für Hexerei und Zauberei",
        introDesc: "Ein verzauberter Brief aus Hogwarts schwebt vor dir in der Luft.<br>Bist du bereit, die Prüfungen abzulegen und deine Hauspunkte zu sichern?",
        diffLabel: "Schwierigkeitsgrad wählen:",
        diffAll: "Alle gemischt",
        diffEasy: "Leicht",
        diffMed: "Mittel",
        diffHard: "Schwer",
        startBtn: "📜 Siegel brechen & Brief öffnen",
        startBtnCasting: "✨ Zauber wird gewirkt...",
        pointsLabel: "🏆 Hauspunkte",
        questionLabel: "Frage",
        ofLabel: "von",
        attemptLabel: "Versuch",
        checkBtn: "✨ Antwort prüfen",
        hintBtn: "💡 Hinweis anzeigen",
        hintHeading: "📜 Notiz aus der verbotenen Abteilung:",
        placeholder: "Deine Antwort hier eingeben...",
        noHint: "Kein Tipp vorhanden.",
        hintFailed: "Tipp konnte nicht geladen werden.",
        correctFeedback: "✨ Richtig! 1 Hauspunkt für dein Haus! ✨",
        wrongFeedback: "Leider falsch! Noch {attempts} Versuch(e).",
        exhaustedWrong: "Leider nicht richtig (3 Fehlversuche).",
        solutionLabel: "Richtige Lösung:",
        startError: "Fehler beim Starten des Quiz: ",
        networkError: "Netzwerkfehler: "
    },
    en: {
        pageTitle: "✨ Magical Hogwarts Escape Quiz ✨",
        pageSubtitle: "10 tricky wizarding world puzzles await you",
        envelopeLetter: "Hogwarts School of Witchcraft and Wizardry",
        introDesc: "An enchanted letter from Hogwarts is floating in the air before you.<br>Are you ready to take the exams and secure House Points?",
        diffLabel: "Choose difficulty level:",
        diffAll: "All mixed",
        diffEasy: "Easy",
        diffMed: "Medium",
        diffHard: "Hard",
        startBtn: "📜 Break Seal & Open Letter",
        startBtnCasting: "✨ Casting spell...",
        pointsLabel: "🏆 House Points",
        questionLabel: "Question",
        ofLabel: "of",
        attemptLabel: "Attempt",
        checkBtn: "✨ Check Answer",
        hintBtn: "💡 Show Hint",
        hintHeading: "📜 Note from the Restricted Section:",
        placeholder: "Type your answer here...",
        noHint: "No hint available.",
        hintFailed: "Could not load hint.",
        correctFeedback: "✨ Correct! 1 House Point for your House! ✨",
        wrongFeedback: "Incorrect! {attempts} attempt(s) remaining.",
        exhaustedWrong: "Unfortunately incorrect (3 failed attempts).",
        solutionLabel: "Correct solution:",
        startError: "Error starting quiz: ",
        networkError: "Network error: "
    }
};

// Web Audio API Sound Generator for magic chimes and buzzers
const audioCtx = new (window.AudioContext || window.webkitAudioContext)();

function playSound(type) {
    if (audioCtx.state === 'suspended') {
        audioCtx.resume();
    }
    if (type === 'magic') {
        // Magical bright arpeggio chime
        const notes = [523.25, 659.25, 783.99, 1046.50]; // C5, E5, G5, C6
        notes.forEach((freq, index) => {
            const osc = audioCtx.createOscillator();
            const gain = audioCtx.createGain();
            osc.type = 'sine';
            osc.frequency.value = freq;
            gain.gain.setValueAtTime(0.15, audioCtx.currentTime + index * 0.08);
            gain.gain.exponentialRampToValueAtTime(0.001, audioCtx.currentTime + index * 0.08 + 0.35);
            osc.connect(gain);
            gain.connect(audioCtx.destination);
            osc.start(audioCtx.currentTime + index * 0.08);
            osc.stop(audioCtx.currentTime + index * 0.08 + 0.35);
        });
    } else if (type === 'wrong') {
        // Soft error buzz
        const osc = audioCtx.createOscillator();
        const gain = audioCtx.createGain();
        osc.type = 'sawtooth';
        osc.frequency.setValueAtTime(150, audioCtx.currentTime);
        osc.frequency.exponentialRampToValueAtTime(80, audioCtx.currentTime + 0.25);
        gain.gain.setValueAtTime(0.1, audioCtx.currentTime);
        gain.gain.exponentialRampToValueAtTime(0.001, audioCtx.currentTime + 0.25);
        osc.connect(gain);
        gain.connect(audioCtx.destination);
        osc.start();
        osc.stop(audioCtx.currentTime + 0.25);
    }
}

function selectDifficulty(diff) {
    selectedDifficulty = diff;
    document.querySelectorAll(".diff-chip").forEach(chip => {
        chip.classList.toggle("active", chip.getAttribute("data-diff") === diff);
    });
}

function onLanguageChange(lang) {
    applyQuizTranslations(lang);
}

function applyQuizTranslations(lang) {
    const t = UI_TEXT[lang] || UI_TEXT.de;
    const pageTitle = document.getElementById("pageTitle");
    const pageSubtitle = document.getElementById("pageSubtitle");
    const envelopeLetter = document.getElementById("envelopeLetter");
    const introDesc = document.getElementById("introDesc");
    const diffLabel = document.getElementById("diffLabel");
    const diffAllText = document.getElementById("diffAllText");
    const diffEasyText = document.getElementById("diffEasyText");
    const diffMedText = document.getElementById("diffMedText");
    const diffHardText = document.getElementById("diffHardText");
    const startBtn = document.getElementById("startBtn");
    const checkBtn = document.getElementById("checkBtn");
    const hintBtn = document.getElementById("hintBtn");
    const hintBtnMC = document.getElementById("hintBtnMC");
    const hintHeading = document.getElementById("hintHeading");
    const answerInput = document.getElementById("answerInput");

    if (pageTitle) pageTitle.innerText = t.pageTitle;
    if (pageSubtitle) pageSubtitle.innerText = t.pageSubtitle;
    if (envelopeLetter) envelopeLetter.innerText = t.envelopeLetter;
    if (introDesc) introDesc.innerHTML = t.introDesc;
    if (diffLabel) diffLabel.innerText = t.diffLabel;
    if (diffAllText) diffAllText.innerText = t.diffAll;
    if (diffEasyText) diffEasyText.innerText = t.diffEasy;
    if (diffMedText) diffMedText.innerText = t.diffMed;
    if (diffHardText) diffHardText.innerText = t.diffHard;
    if (startBtn && !startBtn.disabled) startBtn.innerText = t.startBtn;
    if (checkBtn) checkBtn.innerText = t.checkBtn;
    if (hintBtn) hintBtn.innerText = t.hintBtn;
    if (hintBtnMC) hintBtnMC.innerText = t.hintBtn;
    if (hintHeading) hintHeading.innerText = t.hintHeading;
    if (answerInput) answerInput.placeholder = t.placeholder;

    if (lastQuestionData) {
        renderQuestion(lastQuestionData);
    }
}

let sessionQuestionIds = [];

function getRecentQuestionIds() {
    try {
        const stored = localStorage.getItem("quiz_recent_qids");
        return stored ? JSON.parse(stored) : [];
    } catch(e) {
        return [];
    }
}

function getWrongQuestionIds() {
    try {
        const stored = localStorage.getItem("quiz_wrong_qids");
        return stored ? JSON.parse(stored) : [];
    } catch(e) {
        return [];
    }
}

function recordQuestionWrong(qid) {
    if (!qid) return;
    try {
        const wrong = getWrongQuestionIds();
        if (!wrong.includes(qid)) {
            wrong.push(qid);
            if (wrong.length > 30) wrong.shift();
            localStorage.setItem("quiz_wrong_qids", JSON.stringify(wrong));
        }
    } catch(e) {}
}

function recordQuestionMastered(qid) {
    if (!qid) return;
    try {
        let wrong = getWrongQuestionIds();
        if (wrong.includes(qid)) {
            wrong = wrong.filter(id => id !== qid);
            localStorage.setItem("quiz_wrong_qids", JSON.stringify(wrong));
        }
    } catch(e) {}
}

function saveRecentQuestions(ids) {
    if (!ids || ids.length === 0) return;
    try {
        let recent = getRecentQuestionIds();
        recent = Array.from(new Set([...ids, ...recent])).slice(0, 20);
        localStorage.setItem("quiz_recent_qids", JSON.stringify(recent));
    } catch(e) {}
}

async function startGame() {
    const envelope = document.getElementById("envelope");
    const startBtn = document.getElementById("startBtn");
    const t = UI_TEXT[currentLang] || UI_TEXT.de;

    startBtn.disabled = true;
    startBtn.innerText = t.startBtnCasting;
    envelope.classList.add("envelope-opened");
    sessionQuestionIds = [];

    // Start background music if enabled or first click
    const bgm = document.getElementById("bgm");
    if (bgm && bgm.paused) {
        bgm.play().then(() => {
            const icon = document.getElementById("audioIcon");
            const text = document.getElementById("audioText");
            if (icon && text) {
                icon.innerText = "🔊";
                text.innerText = (currentLang === "de") ? "Musik: An" : "Music: On";
            }
            localStorage.setItem("bgm_enabled", "true");
        }).catch(() => {});
    }

    try {
        const recentIds = getRecentQuestionIds();
        const wrongIds = getWrongQuestionIds();

        const res = await fetch("/api/game/start", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({
                lang: currentLang,
                difficulty: selectedDifficulty,
                recent_ids: recentIds,
                wrong_ids: wrongIds
            })
        });

        if (!res.ok) {
            throw new Error(currentLang === "en" ? "Could not start game session." : "Konnte Spiel nicht starten.");
        }

        const data = await res.json();
        currentSessionId = data.session_id;
        currentQuestionNumber = data.question_number;
        totalQuestions = data.total_questions;
        currentScore = data.score;
        attemptsUsed = data.attempts_used;

        setTimeout(() => {
            document.getElementById("introCard").classList.add("hidden");
            document.getElementById("gameCard").classList.remove("hidden");
            startTimer();
            renderQuestion(data);
        }, 1100);

    } catch (err) {
        alert(t.startError + err.message);
        startBtn.disabled = false;
        startBtn.innerText = t.startBtn;
        envelope.classList.remove("envelope-opened");
    }
}

function startTimer() {
    timerStartTime = Date.now();
    elapsedSeconds = 0;
    if (timerInterval) clearInterval(timerInterval);
    timerInterval = setInterval(updateTimer, 1000);
    updateTimer();
}

function updateTimer() {
    if (!timerStartTime) return;
    elapsedSeconds = Math.floor((Date.now() - timerStartTime) / 1000);
    const m = Math.floor(elapsedSeconds / 60);
    const s = elapsedSeconds % 60;
    const badge = document.getElementById("timerBadge");
    if (badge) {
        badge.innerText = `⏱️ ${String(m).padStart(2, '0')}:${String(s).padStart(2, '0')}`;
    }
}

function renderQuestion(qData) {
    lastQuestionData = qData;
    if (qData.id && !sessionQuestionIds.includes(qData.id)) {
        sessionQuestionIds.push(qData.id);
    }
    const t = UI_TEXT[currentLang] || UI_TEXT.de;

    document.getElementById("questionCounter").innerText = `${t.questionLabel} ${qData.question_number} ${t.ofLabel} ${totalQuestions}`;
    document.getElementById("pointsCounter").innerText = `${t.pointsLabel}: ${currentScore}`;
    document.getElementById("badgeCategory").innerText = `⚡ ${qData.category.replace("_", " ").toUpperCase()}`;

    // Difficulty badge
    const badgeDiff = document.getElementById("badgeDifficulty");
    if (badgeDiff) {
        const diff = qData.difficulty || "medium";
        badgeDiff.className = `badge badge-diff badge-diff-${diff}`;
        let diffText = t.diffMed;
        let diffIcon = "🟡";
        if (diff === "easy") {
            diffText = t.diffEasy;
            diffIcon = "🟢";
        } else if (diff === "hard") {
            diffText = t.diffHard;
            diffIcon = "🔴";
        }
        badgeDiff.innerText = `${diffIcon} ${diffText}`;
    }

    document.getElementById("attemptBadge").innerText = `${t.attemptLabel} ${attemptsUsed + 1} ${t.ofLabel} ${maxAttempts}`;
    document.getElementById("frageText").innerText = qData.question;

    const textGroup = document.getElementById("textAnswerGroup");
    const choiceGroup = document.getElementById("choiceAnswerGroup");
    const choiceContainer = document.getElementById("choiceOptionsContainer");
    const input = document.getElementById("answerInput");

    document.getElementById("hintBox").classList.add("hidden");
    document.getElementById("feedbackBox").innerHTML = "";

    if (qData.question_type === "multiple_choice" && qData.options && qData.options.length > 0) {
        textGroup.classList.add("hidden");
        choiceGroup.classList.remove("hidden");
        choiceContainer.innerHTML = "";

        const letters = ["A", "B", "C", "D", "E", "F"];
        qData.options.forEach((opt, idx) => {
            const btn = document.createElement("button");
            btn.className = "choice-btn";
            btn.type = "button";
            btn.innerHTML = `<span class="choice-letter">${letters[idx] || "•"}</span> <span class="choice-text">${opt}</span>`;
            btn.onclick = () => submitAnswer(opt, btn);
            choiceContainer.appendChild(btn);
        });
    } else {
        choiceGroup.classList.add("hidden");
        textGroup.classList.remove("hidden");
        input.value = "";
        input.placeholder = t.placeholder;
        input.disabled = false;
        document.getElementById("checkBtn").disabled = false;
        input.focus();
    }

    const hintBtn = document.getElementById("hintBtn");
    if (hintBtn) hintBtn.disabled = false;
    const hintBtnMC = document.getElementById("hintBtnMC");
    if (hintBtnMC) hintBtnMC.disabled = false;

    updateProgress();
}

function updateProgress() {
    const percent = ((currentQuestionNumber - 1) / totalQuestions) * 100;
    document.getElementById("progressBar").style.width = percent + "%";
}

function checkAnswer() {
    const input = document.getElementById("answerInput");
    const answer = input.value.trim();
    if (!answer) {
        input.focus();
        return;
    }
    submitAnswer(answer);
}

async function submitAnswer(answer, clickedBtn = null) {
    const checkBtn = document.getElementById("checkBtn");
    const input = document.getElementById("answerInput");
    const t = UI_TEXT[currentLang] || UI_TEXT.de;

    if (checkBtn) checkBtn.disabled = true;
    if (input) input.disabled = true;

    // Disable all choice buttons
    const choiceBtns = document.querySelectorAll(".choice-btn");
    choiceBtns.forEach(b => b.disabled = true);
    if (clickedBtn) {
        clickedBtn.classList.add("choice-selected");
    }

    try {
        const res = await fetch("/api/game/check", {
            method: "POST",
            headers: { "Content-Type": "application/json" },
            body: JSON.stringify({
                session_id: currentSessionId,
                answer: answer
            })
        });

        if (!res.ok) {
            throw new Error(currentLang === "en" ? "Answer check failed." : "Fehler bei der Antwortprüfung.");
        }

        const result = await res.json();
        currentScore = result.score;
        document.getElementById("pointsCounter").innerText = `${t.pointsLabel}: ${currentScore}`;

        const frageBox = document.getElementById("frageBox");
        const feedbackBox = document.getElementById("feedbackBox");

        if (result.correct) {
            // Success!
            playSound('magic');
            if (clickedBtn) {
                clickedBtn.classList.remove("choice-selected");
                clickedBtn.classList.add("choice-correct");
            }
            frageBox.classList.add("sparkle-effect");

            // Mark question as mastered in history
            if (result.question_id) {
                recordQuestionMastered(result.question_id);
            }

            const pts = result.points_earned || 100;
            const ptsText = (currentLang === "en")
                ? `✨ Correct! +${pts} House Points! ✨`
                : `✨ Richtig! +${pts} Hauspunkte für dein Haus! ✨`;
            feedbackBox.innerHTML = `<span class="feedback-correct">${ptsText}</span>`;

            setTimeout(() => {
                frageBox.classList.remove("sparkle-effect");
                if (result.is_finished) {
                    finishGame();
                } else if (result.next_question) {
                    currentQuestionNumber = result.next_question.question_number;
                    attemptsUsed = 0;
                    renderQuestion(result.next_question);
                }
            }, 1200);

        } else {
            // Incorrect
            playSound('wrong');
            if (clickedBtn) {
                clickedBtn.classList.remove("choice-selected");
                clickedBtn.classList.add("choice-wrong");
            }
            frageBox.classList.add("shake-effect");
            setTimeout(() => frageBox.classList.remove("shake-effect"), 500);

            attemptsUsed = result.attempts_used;
            document.getElementById("attemptBadge").innerText = `${t.attemptLabel} ${Math.min(attemptsUsed + 1, maxAttempts)} ${t.ofLabel} ${maxAttempts}`;

            if (result.attempts_left === 0) {
                // Exhausted all attempts -> record for spaced repetition learning
                if (result.question_id) {
                    recordQuestionWrong(result.question_id);
                }

                feedbackBox.innerHTML = `
                    <div class="feedback-wrong">${t.exhaustedWrong}</div>
                    <div class="feedback-revealed">${t.solutionLabel} <strong>${result.revealed_answer}</strong></div>
                `;

                setTimeout(() => {
                    if (result.is_finished) {
                        finishGame();
                    } else if (result.next_question) {
                        currentQuestionNumber = result.next_question.question_number;
                        attemptsUsed = 0;
                        renderQuestion(result.next_question);
                    }
                }, 2200);

            } else {
                // Still attempts remaining
                const msg = t.wrongFeedback.replace("{attempts}", result.attempts_left);
                feedbackBox.innerHTML = `<span class="feedback-wrong">${msg}</span>`;
                if (checkBtn) checkBtn.disabled = false;
                if (input) {
                    input.disabled = false;
                    input.select();
                }
                // Re-enable choice buttons
                choiceBtns.forEach(b => b.disabled = false);
            }
        }

    } catch (err) {
        alert(t.networkError + err.message);
        if (checkBtn) checkBtn.disabled = false;
        if (input) input.disabled = false;
        choiceBtns.forEach(b => b.disabled = false);
    }
}

async function requestHint() {
    if (!currentSessionId) return;
    const hintBox = document.getElementById("hintBox");
    const hintText = document.getElementById("hintText");
    const t = UI_TEXT[currentLang] || UI_TEXT.de;

    try {
        const res = await fetch(`/api/game/hint?session_id=${encodeURIComponent(currentSessionId)}`);
        const data = await res.json();
        hintText.innerText = data.hint || t.noHint;
        hintBox.classList.remove("hidden");
    } catch (err) {
        hintText.innerText = t.hintFailed;
        hintBox.classList.remove("hidden");
    }
}

function finishGame() {
    if (timerInterval) clearInterval(timerInterval);
    saveRecentQuestions(sessionQuestionIds);
    document.getElementById("progressBar").style.width = "100%";
    window.location.href = `/finale?score=${currentScore}&total=${totalQuestions}&time=${elapsedSeconds}&lang=${currentLang}&diff=${encodeURIComponent(selectedDifficulty)}`;
}

// Enter key to submit
document.addEventListener("DOMContentLoaded", () => {
    const input = document.getElementById("answerInput");
    if (input) {
        input.addEventListener("keydown", (e) => {
            if (e.key === "Enter") {
                e.preventDefault();
                checkAnswer();
            }
        });
    }
    applyQuizTranslations(currentLang);
});