let currentSession = {
    topic: null,
    currentQuestion: null,
    questionIndex: null,
    totalScore: 0,
    questionCount: 0
};

// Voice recognition setup
let recognition = null;
if ('webkitSpeechRecognition' in window || 'SpeechRecognition' in window) {
    const SpeechRecognition = window.SpeechRecognition || window.webkitSpeechRecognition;
    recognition = new SpeechRecognition();
    recognition.continuous = false;
    recognition.interimResults = false;
    recognition.lang = 'en-US';

    recognition.onresult = (event) => {
        const transcript = event.results[0][0].transcript;
        document.getElementById('studentAnswer').value = transcript;
    };

    recognition.onerror = (event) => {
        console.error('Speech recognition error:', event.error);
        stopVoiceInput();
    };
}

async function startSession(topic) {
    try {
        const response = await fetch('/api/start_session', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({ topic: topic })
        });

        const data = await response.json();

        if (data.status === 'started') {
            currentSession.topic = topic;
            currentSession.totalScore = 0;
            currentSession.questionCount = 0;

            displayQuestion(data.first_question);

            document.getElementById('sessionTopic').textContent = `Topic: ${getTopicName(topic)}`;
            document.getElementById('topicSelection').classList.add('hidden');
            document.getElementById('vivaSession').classList.remove('hidden');

            updateProgress();
        }

    } catch (error) {
        console.error('Error starting session:', error);
        alert('Failed to start session. Please try again.');
    }
}

function getTopicName(topicKey) {
    const topicNames = {
        'upper_limb': 'Upper Limb Anatomy',
        'lower_limb': 'Lower Limb Anatomy',
        'cardiology': 'Cardiac Anatomy',
        'neuroanatomy': 'Neuroanatomy'
    };
    return topicNames[topicKey] || topicKey;
}

function displayQuestion(questionData) {
    if (questionData.completed) {
        endSession();
        return;
    }

    currentSession.currentQuestion = questionData.question;
    currentSession.questionIndex = questionData.question_index;

    document.getElementById('questionText').textContent = questionData.question;
    document.getElementById('studentAnswer').value = '';
    document.getElementById('feedbackArea').classList.add('hidden');

    updateProgress();
}

async function speakCurrentQuestion() {
    const questionText = currentSession.currentQuestion;
    if (!questionText) return;

    const listeningIndicator = document.getElementById('listeningIndicator');
    listeningIndicator.classList.remove('hidden');

    try {
        const response = await fetch('/api/text_to_speech', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({ text: questionText })
        });

        const data = await response.json();

        if (data.audio_data) {
            await playAudioData(data.audio_data);
        }
    } catch (error) {
        console.error('TTS failed:', error);
        // Fallback to browser TTS
        speakWithBrowserTTS(questionText);
    } finally {
        listeningIndicator.classList.add('hidden');
    }
}

async function playAudioData(base64Audio) {
    return new Promise((resolve) => {
        const audioBlob = base64ToBlob(base64Audio, 'audio/wav');
        const audioUrl = URL.createObjectURL(audioBlob);
        const audio = new Audio(audioUrl);

        audio.onended = () => {
            URL.revokeObjectURL(audioUrl);
            resolve();
        };

        audio.onerror = () => resolve();

        audio.play().catch(error => {
            console.error('Audio play failed:', error);
            resolve();
        });
    });
}

function speakWithBrowserTTS(text) {
    if ('speechSynthesis' in window) {
        const utterance = new SpeechSynthesisUtterance(text);
        utterance.rate = 0.8;
        utterance.pitch = 1.0;

        const voices = speechSynthesis.getVoices();
        const englishVoice = voices.find(voice => voice.lang.startsWith('en-'));
        if (englishVoice) {
            utterance.voice = englishVoice;
        }

        speechSynthesis.speak(utterance);
    }
}

function toggleVoiceInput() {
    const voiceBtn = document.getElementById('voiceBtn');

    if (!recognition) {
        alert('Speech recognition not supported in this browser. Please use Chrome or Edge.');
        return;
    }

    if (voiceBtn.textContent.includes('Start')) {
        startVoiceInput();
    } else {
        stopVoiceInput();
    }
}

function startVoiceInput() {
    const voiceBtn = document.getElementById('voiceBtn');
    voiceBtn.textContent = '🛑 Stop Listening';
    voiceBtn.style.background = '#e74c3c';

    recognition.start();
}

function stopVoiceInput() {
    const voiceBtn = document.getElementById('voiceBtn');
    voiceBtn.textContent = '🎤 Voice Input';
    voiceBtn.style.background = '#9b59b6';

    if (recognition) {
        recognition.stop();
    }
}

async function submitAnswer() {
    const answer = document.getElementById('studentAnswer').value.trim();

    if (!answer) {
        alert('Please enter your answer');
        return;
    }

    try {
        const response = await fetch('/api/evaluate_answer', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
            },
            body: JSON.stringify({
                question_index: currentSession.questionIndex,
                answer: answer
            })
        });

        const data = await response.json();

        displayFeedback(data);

    } catch (error) {
        console.error('Error submitting answer:', error);
        alert('Failed to submit answer. Please try again.');
    }
}

function displayFeedback(data) {
    currentSession.totalScore += data.score;
    currentSession.questionCount++;

    document.getElementById('feedbackText').textContent = data.feedback;
    document.getElementById('scoreValue').textContent = data.score.toFixed(1);
    document.getElementById('totalScore').textContent = currentSession.totalScore.toFixed(1);
    document.getElementById('feedbackArea').classList.remove('hidden');

    updateProgress();
    addToHistory(data);
}

function addToHistory(data) {
    const historyContainer = document.getElementById('conversationHistory');
    const historyItem = document.createElement('div');
    historyItem.className = 'history-item';

    historyItem.innerHTML = `
        <strong>Q${currentSession.questionCount}:</strong> ${currentSession.currentQuestion}<br>
        <strong>Your Answer:</strong> ${data.transcribed_answer || document.getElementById('studentAnswer').value.substring(0, 100)}...<br>
        <strong>Score:</strong> ${data.score.toFixed(1)}/10
    `;

    historyContainer.appendChild(historyItem);
    historyContainer.scrollTop = historyContainer.scrollHeight;
}

function updateProgress() {
    const progressFill = document.querySelector('.progress-fill');
    if (currentSession.questionCount > 0) {
        const progress = (currentSession.questionCount / 5) * 100; // Assuming 5 questions per topic
        progressFill.style.width = `${Math.min(progress, 100)}%`;
    } else {
        progressFill.style.width = '0%';
    }
}

function nextQuestion() {
    // In a real implementation, this would get the next question from the server
    // For now, we'll simulate by ending the session after a few questions
    if (currentSession.questionCount >= 3) {
        endSession();
    } else {
        // Simulate getting next question
        const nextQuestion = {
            question: `Next question about ${currentSession.topic}...`,
            question_index: currentSession.questionIndex + 1
        };
        displayQuestion(nextQuestion);
    }
}

function endSession() {
    const averageScore = currentSession.totalScore / currentSession.questionCount;
    alert(`Session completed! Your average score: ${averageScore.toFixed(1)}/10\nWell done!`);
    resetSession();
}

function resetSession() {
    currentSession = {
        topic: null,
        currentQuestion: null,
        questionIndex: null,
        totalScore: 0,
        questionCount: 0
    };

    document.getElementById('vivaSession').classList.add('hidden');
    document.getElementById('topicSelection').classList.remove('hidden');
    document.getElementById('conversationHistory').innerHTML = '';
    document.getElementById('totalScore').textContent = '0';
}

// Utility function
function base64ToBlob(base64, mimeType) {
    const byteCharacters = atob(base64);
    const byteNumbers = new Array(byteCharacters.length);
    for (let i = 0; i < byteCharacters.length; i++) {
        byteNumbers[i] = byteCharacters.charCodeAt(i);
    }
    const byteArray = new Uint8Array(byteNumbers);
    return new Blob([byteArray], { type: mimeType });
}

// Initialize speech synthesis voices
if ('speechSynthesis' in window) {
    speechSynthesis.getVoices();
}