src/views/InstructorView.js

import { createRoom, subscribeToRoom, getChallenges, resetProgress } from "../services/classroom.js";

let cachedChallenges = [];

export async function renderInstructorView() {
    // Pre-fetch challenges for table headers
    try {
        cachedChallenges = await getChallenges();
    } catch (e) {
        console.error("Failed header load", e);
    }

    return `
    <div id="auth-modal" class="fixed inset-0 bg-black bg-opacity-90 backdrop-blur z-50 flex items-center justify-center">
        <div class="bg-gray-800 p-8 rounded-xl border border-gray-600 shadow-2xl max-w-sm w-full">
            <h2 class="text-xl font-bold text-center mb-6 text-white">🔒 講師身分驗證</h2>
            <input type="password" id="instructor-password" class="w-full bg-gray-900 border border-gray-700 rounded p-3 text-white text-center text-lg tracking-widest mb-4 focus:border-cyan-500 focus:outline-none" placeholder="輸入密碼">
            <button id="auth-btn" class="w-full bg-purple-600 hover:bg-purple-500 text-white font-bold py-3 rounded-lg transition-colors">確認進入</button>
        </div>
    </div>

    <!-- Broadcast Modal (Hidden by default) -->
    <div id="broadcast-modal" class="fixed inset-0 bg-black/90 backdrop-blur z-50 hidden flex flex-col items-center justify-center p-8 transition-opacity duration-300">
        <button onclick="closeBroadcast()" class="absolute top-6 right-6 text-gray-400 hover:text-white text-2xl">✕</button>
        
        <div id="broadcast-content" class="bg-gray-800 border border-gray-600 rounded-2xl p-8 max-w-4xl w-full text-center shadow-2xl transform transition-transform scale-95 opacity-0">
            <div class="mb-4 flex flex-col items-center">
                <div class="w-16 h-16 rounded-full bg-cyan-600 flex items-center justify-center text-3xl font-bold text-white mb-2" id="broadcast-avatar">
                    D
                </div>
                <h3 class="text-xl text-cyan-300 font-bold" id="broadcast-author">Dave</h3>
                <span class="text-gray-500 text-sm" id="broadcast-challenge">Challenge Name</span>
            </div>
            
            <div class="bg-black/30 rounded-xl p-6 mb-8 text-left overflow-auto max-h-[50vh]">
                <pre class="text-green-400 font-mono text-lg whitespace-pre-wrap" id="broadcast-prompt">Loading...</pre>
            </div>

            <div class="flex justify-center space-x-4">
               <button id="btn-show-stage" class="bg-blue-600 hover:bg-blue-500 text-white font-bold py-3 px-8 rounded-xl flex items-center space-x-2 text-lg">
                    <span>🖥️ 投放到大螢幕 (本機)</span>
               </button>
               <button id="btn-reject-task" class="bg-red-600 hover:bg-red-500 text-white font-bold py-3 px-8 rounded-xl flex items-center space-x-2 text-lg shadow-lg">
                    <span>🛑 退回重做 (Reject)</span>
               </button>
               <!-- Future Feature: Send to Students -->
               <!-- 
               <button id="btn-broadcast-all" class="bg-purple-600 hover:bg-purple-500 text-white font-bold py-3 px-8 rounded-xl flex items-center space-x-2 text-lg opacity-50 cursor-not-allowed" title="此功能開發中">
                    <span>📡 推送給所有人</span>
               </button>
               -->
            </div>
        </div>
        
        <!-- Big Screen Mode (Initially hidden inside modal) -->
        <div id="stage-view" class="hidden absolute inset-0 bg-gray-900 flex flex-col items-center justify-center p-10">
             <button onclick="closeStage()" class="absolute top-6 right-6 text-gray-500 hover:text-white text-4xl">✕</button>
             <h1 class="text-4xl font-bold text-cyan-400 mb-8" id="stage-title">優秀作品展示</h1>
             <div class="bg-black border-2 border-cyan-500/50 rounded-2xl p-10 max-w-6xl w-full shadow-[0_0_50px_rgba(6,182,212,0.2)]">
                <pre class="text-3xl text-green-400 font-mono whitespace-pre-wrap leading-relaxed" id="stage-prompt">...</pre>
             </div>
             <div class="mt-8 text-2xl text-gray-400">
                Author: <span class="text-white font-bold" id="stage-author">Dave</span>
             </div>
        </div>
    </div>

    <div class="min-h-screen p-6 pb-20 bg-gray-900 text-white">
        <!-- Header -->
        <header class="flex flex-col md:flex-row justify-between items-center mb-6 bg-gray-800 p-4 rounded-xl border border-gray-700 space-y-4 md:space-y-0 sticky top-0 z-30 shadow-lg">
            <div class="flex items-center space-x-4">
                <h1 class="text-2xl font-bold text-transparent bg-clip-text bg-gradient-to-r from-purple-400 to-pink-600">
                    儀表板
                </h1>
                <div id="room-info" class="hidden flex items-center space-x-2 bg-black/30 px-3 py-1 rounded-lg border border-gray-700">
                    <span class="text-xs text-gray-500 uppercase">Room</span>
                    <span id="display-room-code" class="text-xl font-mono font-bold text-cyan-400 tracking-widest"></span>
                </div>
            </div>
            
            <div class="flex space-x-3">
                <div class="flex items-center space-x-2 text-xs text-gray-400 mr-4 border-r border-gray-700 pr-4">
                    <div class="flex items-center"><div class="w-3 h-3 bg-gray-700 rounded-sm mr-1"></div> 未開始</div>
                    <div class="flex items-center"><div class="w-3 h-3 bg-blue-600 rounded-sm mr-1"></div> 進行中</div>
                    <div class="flex items-center"><div class="w-3 h-3 bg-green-500 rounded-sm mr-1"></div> 已完成</div>
                    <div class="flex items-center"><div class="w-3 h-3 bg-red-500 animate-pulse rounded-sm mr-1"></div> 卡關 (>5m)</div>
                </div>

                <button id="nav-admin-btn" class="bg-gray-700 hover:bg-gray-600 text-white font-bold py-2 px-4 rounded-lg transition-all border border-gray-600">
                    管理題目
                </button>
                <div id="create-room-container" class="flex items-center space-x-2">
                    <input type="text" id="rejoin-room-code" placeholder="代碼" class="bg-gray-900 border border-gray-700 text-white px-3 py-2 rounded-lg w-20 text-center focus:outline-none focus:border-cyan-500">
                    <button id="rejoin-room-btn" class="bg-gray-700 hover:bg-gray-600 text-white px-3 py-2 rounded-lg">重回</button>
                    <button id="create-room-btn" class="bg-purple-600 hover:bg-purple-500 text-white font-bold px-4 py-2 rounded-lg shadow-lg">開房</button>
                </div>
            </div>
        </header>

        <!-- Heatmap Content -->
        <div id="dashboard-content" class="hidden overflow-x-auto pb-10">
            <table class="w-full border-collapse">
                <thead>
                    <tr id="heatmap-header">
                        <th class="p-3 text-left sticky left-0 bg-gray-800 z-20 border-b border-gray-700 min-w-[150px]">學員 / 關卡</th>
                        <!-- Challenges headers generated dynamically -->
                    </tr>
                </thead>
                <tbody id="heatmap-body">
                    <!-- Rows generated dynamically -->
                    <tr><td colspan="100" class="text-center py-10 text-gray-500">等待資料載入...</td></tr>
                </tbody>
            </table>
        </div>
    </div>
    `;
}

export function setupInstructorEvents() {
    // Auth Logic
    const authBtn = document.getElementById('auth-btn');
    const pwdInput = document.getElementById('instructor-password');
    const authModal = document.getElementById('auth-modal');

    // Default password check
    const checkPassword = async () => {
        const { verifyInstructorPassword } = await import("../services/classroom.js");

        authBtn.textContent = "驗證中...";
        authBtn.disabled = true;

        try {
            const isValid = await verifyInstructorPassword(pwdInput.value);
            if (isValid) {
                authModal.classList.add('hidden');
                // Store session to avoid re-login on reload (Optional, for now just per session)
            } else {
                alert('密碼錯誤');
                pwdInput.value = '';
            }
        } catch (e) {
            console.error(e);
            alert("驗證出錯");
        } finally {
            authBtn.textContent = "確認進入";
            authBtn.disabled = false;
        }
    };

    authBtn.addEventListener('click', checkPassword);
    pwdInput.addEventListener('keypress', (e) => {
        if (e.key === 'Enter') checkPassword();
    });

    const createBtn = document.getElementById('create-room-btn');
    const roomInfo = document.getElementById('room-info');
    const createContainer = document.getElementById('create-room-container');
    const dashboardContent = document.getElementById('dashboard-content');
    const displayRoomCode = document.getElementById('display-room-code');
    const navAdminBtn = document.getElementById('nav-admin-btn');

    navAdminBtn.addEventListener('click', () => {
        // Save current room to return later
        const currentRoom = localStorage.getItem('vibecoding_instructor_room');
        localStorage.setItem('vibecoding_admin_referer', 'instructor'); // track entry source
        window.location.hash = 'admin';
    });

    // Auto-fill code
    const savedRoomCode = localStorage.getItem('vibecoding_instructor_room');
    if (savedRoomCode) {
        document.getElementById('rejoin-room-code').value = savedRoomCode;
    }

    const rejoinBtn = document.getElementById('rejoin-room-btn');
    rejoinBtn.addEventListener('click', () => {
        const code = document.getElementById('rejoin-room-code').value.trim();
        if (!code) return alert('請輸入教室代碼');
        enterRoom(code);
    });

    createBtn.addEventListener('click', async () => {
        try {
            createBtn.disabled = true;
            createBtn.textContent = "...";
            const roomCode = await createRoom();
            enterRoom(roomCode);
        } catch (error) {
            console.error(error);
            alert("建立失敗");
            createBtn.disabled = false;
        }
    });

    function enterRoom(roomCode) {
        createContainer.classList.add('hidden');
        roomInfo.classList.remove('hidden');
        dashboardContent.classList.remove('hidden');
        displayRoomCode.textContent = roomCode;
        localStorage.setItem('vibecoding_instructor_room', roomCode);

        // Subscribe to updates
        subscribeToRoom(roomCode, (students) => {
            renderTransposedHeatmap(students);
        });
    }

    // Modal Events
    window.closeBroadcast = () => {
        const modal = document.getElementById('broadcast-modal');
        const content = document.getElementById('broadcast-content');
        content.classList.remove('opacity-100', 'scale-100');
        content.classList.add('scale-95', 'opacity-0');
        setTimeout(() => modal.classList.add('hidden'), 300);
    };

    window.openStage = (prompt, author) => {
        document.getElementById('broadcast-content').classList.add('hidden');
        const stage = document.getElementById('stage-view');
        stage.classList.remove('hidden');
        document.getElementById('stage-prompt').textContent = prompt;
        document.getElementById('stage-author').textContent = author;
    };

    window.closeStage = () => {
        document.getElementById('stage-view').classList.add('hidden');
        document.getElementById('broadcast-content').classList.remove('hidden');
    };

    document.getElementById('btn-show-stage').addEventListener('click', () => {
        const prompt = document.getElementById('broadcast-prompt').textContent;
        const author = document.getElementById('broadcast-author').textContent;
        window.openStage(prompt, author);
    });

    // Reject Logic
    document.getElementById('btn-reject-task').addEventListener('click', async () => {
        if (!confirm('確定要退回此題目讓學員重做嗎？')) return;

        // We need student ID (userId) and Challenge ID.
        // Currently showBroadcastModal only receives nickname, title, prompt.
        // We need to attach data-userid and data-challengeid to the modal.
        const modal = document.getElementById('broadcast-modal');
        const userId = modal.dataset.userId;
        const challengeId = modal.dataset.challengeId;
        const roomCode = localStorage.getItem('vibecoding_instructor_room');

        if (userId && challengeId && roomCode) {
            try {
                await resetProgress(userId, roomCode, challengeId);
                // Close modal
                window.closeBroadcast();
            } catch (e) {
                console.error(e);
                alert('退回失敗');
            }
        }
    });
}

/**
 * Renders the Transposed Heatmap (Rows=Challenges, Cols=Students)
 */
function renderTransposedHeatmap(students) {
    const thead = document.getElementById('heatmap-header');
    const tbody = document.getElementById('heatmap-body');

    if (students.length === 0) {
        thead.innerHTML = '<th class="p-4 text-left">等待資料...</th>';
        tbody.innerHTML = '<tr><td class="p-10 text-center text-gray-500">尚無學員加入</td></tr>';
        return;
    }

    // 1. Render Header (Students)
    // Sticky Top for Header Row
    // Sticky Left for the first cell ("Challenge/Student")
    let headerHtml = `
        <th class="p-3 text-left sticky left-0 top-0 bg-gray-800 z-30 border-b border-gray-600 min-w-[200px] border-r border-gray-700 shadow-md">
            <div class="flex justify-between items-end">
                <span class="text-sm text-gray-400">題目</span>
                <span class="text-sm text-cyan-400">學員 (${students.length})</span>
            </div>
        </th>
    `;

    students.forEach(student => {
        headerHtml += `
            <th class="p-2 text-center sticky top-0 bg-gray-800 z-20 border-b border-gray-700 min-w-[80px] group">
                <div class="flex flex-col items-center space-y-2 py-2">
                    <div class="w-8 h-8 rounded-full bg-gradient-to-br from-gray-700 to-gray-600 flex items-center justify-center text-xs font-bold text-white uppercase border border-gray-500 shadow-sm relative">
                        ${student.nickname[0]}
                        <!-- Online Indicator (Simulated) -->
                        <div class="absolute -bottom-1 -right-1 w-3 h-3 bg-green-500 border-2 border-gray-800 rounded-full"></div>
                    </div>
                    <span class="text-xs text-gray-300 font-medium truncate max-w-[80px] writing-vertical-lr" style="writing-mode: vertical-rl; text-orientation: mixed;">
                        ${student.nickname}
                    </span>
                </div>
            </th>
        `;
    });
    thead.innerHTML = headerHtml;

    // 2. Render Body (Challenges as Rows)
    if (cachedChallenges.length === 0) {
        tbody.innerHTML = '<tr><td colspan="100" class="text-center py-4">沒有題目資料</td></tr>';
        return;
    }

    tbody.innerHTML = cachedChallenges.map((c, index) => {
        const colors = { beginner: 'cyan', intermediate: 'blue', advanced: 'purple' };
        const color = colors[c.level] || 'gray';

        // Build Row Cells (One per student)
        const rowCells = students.map(student => {
            const p = student.progress?.[c.id];
            let statusClass = 'bg-gray-800/30 border-gray-800'; // Default
            let content = '';
            let action = '';

            if (p) {
                if (p.status === 'completed') {
                    statusClass = 'bg-green-500/20 border-green-500/50 hover:bg-green-500/40 cursor-pointer shadow-[0_0_10px_rgba(34,197,94,0.1)]';
                    content = '✅';
                    const safePrompt = p.prompt.replace(/"/g, '&quot;').replace(/'/g, "\\'");
                    action = `onclick="window.showBroadcastModal('${student.id}', '${c.id}', '${student.nickname}', '${c.title}', '${safePrompt}')"`;
                } else if (p.status === 'started') {
                    // Check stuck
                    const startedAt = p.timestamp ? p.timestamp.toDate() : new Date();
                    const now = new Date();
                    const diffMins = (now - startedAt) / 1000 / 60;

                    if (diffMins > 5) {
                        statusClass = 'bg-red-900/50 border-red-500 animate-pulse cursor-help';
                        content = '🆘';
                    } else {
                        statusClass = 'bg-blue-600/20 border-blue-500';
                        content = '🔵';
                    }
                }
            }

            return `
                <td class="p-1 border border-gray-800/50 text-center align-middle h-14 hover:bg-white/5 transition-colors">
                    <div class="mx-auto w-10 h-10 rounded-lg border flex items-center justify-center ${statusClass} transition-all duration-300" ${action}>
                        ${content}
                    </div>
                </td>
            `;
        }).join('');

        // Row Header (Challenge Title)
        return `
            <tr class="hover:bg-gray-800/50 transition-colors">
                <td class="p-3 sticky left-0 bg-gray-900 z-10 border-r border-b border-gray-700 shadow-md">
                    <div class="flex items-center justify-between">
                       <div class="flex flex-col">
                           <span class="text-xs text-${color}-400 font-bold uppercase tracking-wider mb-0.5">${c.level}</span>
                           <span class="font-bold text-white text-sm truncate max-w-[180px]" title="${c.title}">${index + 1}. ${c.title}</span>
                       </div>
                       <!-- Stats (Optional) -->
                       <!-- <span class="text-xs text-gray-500">0%</span> -->
                    </div>
                </td>
                ${rowCells}
            </tr>
        `;
    }).join('');
}

// Global scope for HTML access
window.showBroadcastModal = (userId, challengeId, nickname, title, prompt) => {
    const modal = document.getElementById('broadcast-modal');
    const content = document.getElementById('broadcast-content');

    document.getElementById('broadcast-avatar').textContent = nickname[0];
    document.getElementById('broadcast-author').textContent = nickname;
    document.getElementById('broadcast-challenge').textContent = title;
    document.getElementById('broadcast-prompt').textContent = prompt;

    // Store IDs for actions
    modal.dataset.userId = userId;
    modal.dataset.challengeId = challengeId;

    modal.classList.remove('hidden');
    // Animation trigger
    setTimeout(() => {
        content.classList.remove('scale-95', 'opacity-0');
        content.classList.add('opacity-100', 'scale-100');
    }, 10);
};