// 题目数据数组
const questions = [
    // 简单难度题目 (5道)
    {
        difficulty: 'easy',
        text: '下列哪个物理量是矢量？',
        options: ['A. 质量', 'B. 时间', 'C. 位移', 'D. 路程'],
        answer: 'C',
        explanation: '矢量具有大小和方向，位移是矢量，其他选项均为标量。'
    },
    {
        difficulty: 'easy',
        text: '下列哪个物理量是矢量？',
        options: ['A. 质量', 'B. 时间', 'C. 位移', 'D. 路程'],
        answer: 'C',
        explanation: '矢量具有大小和方向，位移是矢量，其他选项均为标量。'
    },
    {
        difficulty: 'easy',
        text: '下列哪个物理量是矢量？',
        options: ['A. 质量', 'B. 时间', 'C. 位移', 'D. 路程'],
        answer: 'C',
        explanation: '矢量具有大小和方向，位移是矢量，其他选项均为标量。'
    },
    {
        difficulty: 'easy',
        text: '下列哪个物理量是矢量？',
        options: ['A. 质量', 'B. 时间', 'C. 位移', 'D. 路程'],
        answer: 'C',
        explanation: '矢量具有大小和方向，位移是矢量，其他选项均为标量。'
    },
    {
        difficulty: 'easy',
        text: '下列哪个物理量是矢量？',
        options: ['A. 质量', 'B. 时间', 'C. 位移', 'D. 路程'],
        answer: 'C',
        explanation: '矢量具有大小和方向，位移是矢量，其他选项均为标量。'
    },
    // 中等难度题目 (5道)
    {
        difficulty: 'medium',
        text: '关于万有引力定律，下列说法正确的是？',
        options: [
            'A. 万有引力只存在于天体之间',
            'B. 万有引力与物体质量成正比，与距离成反比',
            'C. 万有引力的发现者是牛顿',
            'D. 地球对苹果的引力大于苹果对地球的引力'
        ],
        answer: 'C',
        explanation: '万有引力存在于任何有质量的物体之间，A错误；万有引力与距离的平方成反比，B错误；牛顿发现了万有引力定律，C正确；物体间的引力是相互的，大小相等，D错误。'
    },
    {
        difficulty: 'medium',
        text: '关于万有引力定律，下列说法正确的是？',
        options: [
            'A. 万有引力只存在于天体之间',
            'B. 万有引力与物体质量成正比，与距离成反比',
            'C. 万有引力的发现者是牛顿',
            'D. 地球对苹果的引力大于苹果对地球的引力'
        ],
        answer: 'C',
        explanation: '万有引力存在于任何有质量的物体之间，A错误；万有引力与距离的平方成反比，B错误；牛顿发现了万有引力定律，C正确；物体间的引力是相互的，大小相等，D错误。'
    },
    {
        difficulty: 'medium',
        text: '关于万有引力定律，下列说法正确的是？',
        options: [
            'A. 万有引力只存在于天体之间',
            'B. 万有引力与物体质量成正比，与距离成反比',
            'C. 万有引力的发现者是牛顿',
            'D. 地球对苹果的引力大于苹果对地球的引力'
        ],
        answer: 'C',
        explanation: '万有引力存在于任何有质量的物体之间，A错误；万有引力与距离的平方成反比，B错误；牛顿发现了万有引力定律，C正确；物体间的引力是相互的，大小相等，D错误。'
    },
    {
        difficulty: 'medium',
        text: '关于万有引力定律，下列说法正确的是？',
        options: [
            'A. 万有引力只存在于天体之间',
            'B. 万有引力与物体质量成正比，与距离成反比',
            'C. 万有引力的发现者是牛顿',
            'D. 地球对苹果的引力大于苹果对地球的引力'
        ],
        answer: 'C',
        explanation: '万有引力存在于任何有质量的物体之间，A错误；万有引力与距离的平方成反比，B错误；牛顿发现了万有引力定律，C正确；物体间的引力是相互的，大小相等，D错误。'
    },
    {
        difficulty: 'medium',
        text: '关于万有引力定律，下列说法正确的是？',
        options: [
            'A. 万有引力只存在于天体之间',
            'B. 万有引力与物体质量成正比，与距离成反比',
            'C. 万有引力的发现者是牛顿',
            'D. 地球对苹果的引力大于苹果对地球的引力'
        ],
        answer: 'C',
        explanation: '万有引力存在于任何有质量的物体之间，A错误；万有引力与距离的平方成反比，B错误；牛顿发现了万有引力定律，C正确；物体间的引力是相互的，大小相等，D错误。'
    },
    // 困难难度题目 (5道)
    {
        difficulty: 'hard',
        text: '相对论中质量与能量的关系表达式是？',
        options: ['A. E=mc²', 'B. F=ma', 'C. E=hv', 'D. P=mv'],
        answer: 'A',
        explanation: '爱因斯坦的质能方程E=mc²表明质量和能量可以相互转换。'
    },
    {
        difficulty: 'hard',
        text: '相对论中质量与能量的关系表达式是？',
        options: ['A. E=mc²', 'B. F=ma', 'C. E=hv', 'D. P=mv'],
        answer: 'A',
        explanation: '爱因斯坦的质能方程E=mc²表明质量和能量可以相互转换。'
    },
    {
        difficulty: 'hard',
        text: '相对论中质量与能量的关系表达式是？',
        options: ['A. E=mc²', 'B. F=ma', 'C. E=hv', 'D. P=mv'],
        answer: 'A',
        explanation: '爱因斯坦的质能方程E=mc²表明质量和能量可以相互转换。'
    },
    {
        difficulty: 'hard',
        text: '相对论中质量与能量的关系表达式是？',
        options: ['A. E=mc²', 'B. F=ma', 'C. E=hv', 'D. P=mv'],
        answer: 'A',
        explanation: '爱因斯坦的质能方程E=mc²表明质量和能量可以相互转换。'
    },
    {
        difficulty: 'hard',
        text: '相对论中质量与能量的关系表达式是？',
        options: ['A. E=mc²', 'B. F=ma', 'C. E=hv', 'D. P=mv'],
        answer: 'A',
        explanation: '爱因斯坦的质能方程E=mc²表明质量和能量可以相互转换。'
    },
];

// 当前难度级别，初始为中等
let currentDifficulty = 'medium';
// 已完成的难度
const completedDifficulties = [];
// 各难度得分情况
const scores = {
    easy: { score: 0, correct: 0, incorrect: 0 },
    medium: { score: 0, correct: 0, incorrect: 0 },
    hard: { score: 0, correct: 0, incorrect: 0 }
};

// 学伴功能相关变量
let mediaRecorder; let audioChunks = []; let isRecording = false;
let audioElement = null; let isPlaying = false;
let currentQuestion = null;

// DOM元素
const questionContainer = document.getElementById('question-container');
const submitBtn = document.getElementById('submit-btn');
const resultSection = document.getElementById('result-section');
const totalScoreElement = document.getElementById('total-score');
const correctCountElement = document.getElementById('correct-count');
const incorrectCountElement = document.getElementById('incorrect-count');
const navigationSection = document.getElementById('navigation-section');
const navigationMessage = document.getElementById('navigation-message');
const nextBtn = document.getElementById('next-btn');
const difficultyIndicator = document.querySelector('.difficulty-indicator');
// 学伴功能DOM元素
const recordingIndicator = document.getElementById('recordingIndicator');
const thinkingIndicator = document.getElementById('thinkingIndicator');
const resultContainer = document.getElementById('resultContainer');
const asrResultText = document.getElementById('asrResultText');
const feedbackResultText = document.getElementById('feedbackResultText');
const playAudioBtn = document.getElementById('playAudioBtn');
const audioProgress = document.getElementById('audioProgress');
const progressBar = document.getElementById('progressBar');
const audioTime = document.getElementById('audioTime');

// 初始化页面
document.addEventListener('DOMContentLoaded', () => {
    renderQuestions(currentDifficulty);
    // 绑定学伴答疑按钮事件
    document.addEventListener('click', function(e) {
        if (e.target && e.target.classList.contains('ask-xueban-btn')) {
            currentQuestion = {
                number: e.target.dataset.question,
                difficulty: e.target.dataset.difficulty
            };
            startRecording();
        }
    });
});

// 渲染指定难度的题目
function renderQuestions(difficulty) {
    questionContainer.innerHTML = '';

    // 筛选当前难度的题目
    const filteredQuestions = questions.filter(q => q.difficulty === difficulty);

    // 生成题目HTML
    filteredQuestions.forEach((q, index) => {
        const questionNumber = index + 1;
        const questionElement = document.createElement('div');
        questionElement.className = 'question';
        questionElement.dataset.difficulty = q.difficulty;
        questionElement.dataset.question = questionNumber;

        questionElement.innerHTML = `
            <div class="question-header">
                <div class="question-number">${getDifficultyName(q.difficulty)}难度 - 问题 ${questionNumber}</div>
                <div class="question-points">20分</div>
            </div>
            <p class="question-text">${q.text}</p>
            <div class="options">
                ${q.options.map((option, optIndex) => {
                    const optionLetter = String.fromCharCode(65 + optIndex);
                    return `
                    <div class="option">
                        <input type="radio" name="q${q.difficulty}-${questionNumber}" id="q${q.difficulty}-${questionNumber}-${optionLetter.toLowerCase()}" value="${optionLetter}">
                        <label for="q${q.difficulty}-${questionNumber}-${optionLetter.toLowerCase()}">${option}</label>
                    </div>
                    `;
                }).join('')}
            </div>
            <div class="explanation" id="explanation-${q.difficulty}-${questionNumber}">${q.explanation}</div>
            <button class="ask-xueban-btn hidden" data-question="${questionNumber}" data-difficulty="${q.difficulty}">学伴答疑</button>
        `;

        questionContainer.appendChild(questionElement);
    });
}

// 获取难度名称
function getDifficultyName(difficulty) {
    const names = {
        easy: '简单',
        medium: '中等',
        hard: '高级'
    };
    return names[difficulty] || difficulty;
}

// 提交答案
submitBtn.addEventListener('click', () => {
    checkAnswers();
    submitBtn.disabled = true;
    submitBtn.textContent = '已提交';
});

// 检查答案
function checkAnswers() {
    let correctCount = 0;
    let incorrectCount = 0;
    let totalScore = 0;

    // 获取当前难度的题目
    const currentQuestions = questions.filter(q => q.difficulty === currentDifficulty);

    // 检查每道题的答案
    currentQuestions.forEach((q, index) => {
        const questionNumber = index + 1;
        const selectedOption = document.querySelector(`input[name="q${q.difficulty}-${questionNumber}"]:checked`);
        const explanationElement = document.getElementById(`explanation-${q.difficulty}-${questionNumber}`);
        const optionsContainer = document.querySelector(`div[data-difficulty="${q.difficulty}"][data-question="${questionNumber}"] .options`);
        const allOptions = optionsContainer.querySelectorAll('.option');

        // 显示解析
        explanationElement.classList.add('show');

        if (!selectedOption) {
            // 未答题
            optionsContainer.style.border = '2px solid #f39c12';
            return;
        }

        // 标记正确或错误
        const selectedValue = selectedOption.value;
        if (selectedValue === q.answer) {
            // 正确
            selectedOption.closest('.option').classList.add('correct');
            correctCount++;
            totalScore += 20;
        } else {
            // 错误
            selectedOption.closest('.option').classList.add('incorrect');
            // 标记正确答案
            allOptions.forEach(option => {
                if (option.querySelector(`input[value="${q.answer}"]`)) {
                    option.classList.add('correct');
                }
            });
            incorrectCount++;
        }
    });

    // 更新当前难度得分
    scores[currentDifficulty] = {
        score: totalScore,
        correct: correctCount,
        incorrect: incorrectCount
    };

    // 添加到已完成难度
    if (!completedDifficulties.includes(currentDifficulty)) {
        completedDifficulties.push(currentDifficulty);
    }

    // 显示结果
    showResults();

    // 显示下一步建议
    showNextRecommendation();
}

// 显示结果
function showResults() {
    resultSection.style.display = 'block';

    // 计算总得分
    let totalScore = 0;
    let totalCorrect = 0;
    let totalIncorrect = 0;

    completedDifficulties.forEach(difficulty => {
        totalScore += scores[difficulty].score;
        totalCorrect += scores[difficulty].correct;
        totalIncorrect += scores[difficulty].incorrect;
    });

    // 更新结果显示
    totalScoreElement.textContent = totalScore;
    correctCountElement.textContent = totalCorrect;
    incorrectCountElement.textContent = totalIncorrect;

    // 滚动到结果区域
    resultSection.scrollIntoView({ behavior: 'smooth' });
}

// 显示下一步建议
function showNextRecommendation() {
    navigationSection.style.display = 'block';
    const currentScore = scores[currentDifficulty];

    if (currentDifficulty === 'medium') {
        if (currentScore.correct >= 3) {
            navigationMessage.textContent = `恭喜！您在${getDifficultyName(currentDifficulty)}难度中答对了${currentScore.correct}题，表现优秀，建议挑战高级难度。`;
            nextBtn.onclick = () => switchDifficulty('hard');
        } else {
            navigationMessage.textContent = `您在${getDifficultyName(currentDifficulty)}难度中答对了${currentScore.correct}题，建议先尝试简单难度巩固基础。`;
            nextBtn.onclick = () => switchDifficulty('easy');
        }
    } else if (currentDifficulty === 'easy') {
        navigationMessage.textContent = `您已完成${getDifficultyName(currentDifficulty)}难度，建议继续挑战中等难度。`;
        nextBtn.onclick = () => switchDifficulty('medium');
    } else if (currentDifficulty === 'hard') {
        navigationMessage.textContent = `恭喜您完成了所有难度级别！您的总分为${scores.easy.score + scores.medium.score + scores.hard.score}分。`;
        nextBtn.style.display = 'none';
    }

    navigationSection.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}

// 切换难度
function switchDifficulty(nextDifficulty) {
    currentDifficulty = nextDifficulty;
    difficultyIndicator.textContent = `当前难度：${getDifficultyName(nextDifficulty)}`;
    difficultyIndicator.className = `difficulty-indicator difficulty-${nextDifficulty}`;

    // 重置按钮状态
    submitBtn.disabled = false;
    submitBtn.textContent = '提交答案';

    // 隐藏结果和导航区域
    resultSection.style.display = 'none';
    navigationSection.style.display = 'none';

    // 渲染新难度题目
    renderQuestions(nextDifficulty);

    // 滚动到页面顶部
    window.scrollTo({ top: 0, behavior: 'smooth' });
}

// 学伴功能 - 开始录音
function startRecording() {
    if (isRecording) return;

    navigator.mediaDevices.getUserMedia({ audio: true })
        .then(stream => {
            mediaRecorder = new MediaRecorder(stream);
            audioChunks = [];

            mediaRecorder.ondataavailable = event => {
                if (event.data.size > 0) audioChunks.push(event.data);
            };

            mediaRecorder.onstop = () => {
                const audioBlob = new Blob(audioChunks, { type: 'audio/wav' });
                uploadAudioToServer(audioBlob);
            };

            mediaRecorder.start();
            isRecording = true;
            recordingIndicator.style.display = 'flex';

            // 设置最长录音时间为60秒
            setTimeout(stopRecording, 60000);
        })
        .catch(error => {
            console.error("获取麦克风权限失败:", error);
            alert("请授权麦克风权限以使用录音功能");
        });
}

// 学伴功能 - 停止录音
function stopRecording() {
    if (!isRecording || !mediaRecorder) return;

    mediaRecorder.stop();
    isRecording = false;
    recordingIndicator.style.display = 'none';

    if (mediaRecorder.stream) {
        mediaRecorder.stream.getTracks().forEach(track => track.stop());
    }
}

// 学伴功能 - 上传音频到服务器
function uploadAudioToServer(audioBlob) {
    thinkingIndicator.style.display = 'flex';
    resultContainer.style.display = 'none';

    const formData = new FormData();
    formData.append('file', audioBlob, 'recording.wav');
    if (currentQuestion) {
        formData.append('question_number', currentQuestion.number);
        formData.append('difficulty', currentQuestion.difficulty);
    }

    fetch('/api/xueban/upload-audio', { method: 'POST', body: formData })
        .then(response => response.json())
        .then(data => {
            thinkingIndicator.style.display = 'none';
            if (data.success) {
                asrResultText.textContent = data.asr_text || '未识别到内容';
                feedbackResultText.textContent = data.feedback_text || '无反馈内容';
                resultContainer.style.display = 'flex';

                if (data.audio_url) {
                    audioElement = new Audio(data.audio_url);
                    audioElement.onloadedmetadata = function() { updateAudioTimeDisplay(); };
                    audioElement.ontimeupdate = function() { updateAudioProgress(); updateAudioTimeDisplay(); };
                    audioElement.onended = function() { isPlaying = false; updatePlayButton(); };
                    playAudioBtn.onclick = togglePlayAudio;
                    audioProgress.onclick = function(e) {
                        const rect = audioProgress.getBoundingClientRect();
                        const clickPosition = (e.clientX - rect.left) / rect.width;
                        audioElement.currentTime = clickPosition * audioElement.duration;
                    };
                }
            } else {
                alert('音频处理失败: ' + data.message);
            }
        })
        .catch(error => {
            thinkingIndicator.style.display = 'none';
            alert('上传音频失败: ' + error.message);
        });
}

// 学伴功能 - 切换音频播放/暂停
function togglePlayAudio() {
    if (!audioElement) return;
    isPlaying ? audioElement.pause() : audioElement.play();
    isPlaying = !isPlaying;
    updatePlayButton();
}

// 学伴功能 - 更新播放按钮状态
function updatePlayButton() {
    playAudioBtn.innerHTML = isPlaying ? 
        `<svg width="20" height="20" viewBox="0 0 24 24" fill="none"><path d="M6 19H10V5H6V19ZM14 19H18V5H14V19Z" fill="white"/></svg>` : 
        `<svg width="20" height="20" viewBox="0 0 24 24" fill="none"><path d="M8 5V19L19 12L8 5Z" fill="white"/></svg>`;
}

// 学伴功能 - 更新音频进度条
function updateAudioProgress() {
    if (audioElement && audioElement.duration) {
        progressBar.style.width = `${(audioElement.currentTime / audioElement.duration) * 100}%`;
    }
}

// 学伴功能 - 更新音频时间显示
function updateAudioTimeDisplay() {
    if (audioElement && audioElement.duration) {
        const currentTime = formatTime(audioElement.currentTime);
        const duration = formatTime(audioElement.duration);
        audioTime.textContent = `${currentTime} / ${duration}`;
    }
}

// 学伴功能 - 格式化时间为 MM:SS
function formatTime(seconds) {
    const mins = Math.floor(seconds / 60);
    const secs = Math.floor(seconds % 60);
    return `${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}`;
}