const API_URL = '/api/v1/index.php?request=';

// --- IndexedDB Configuration ---
const dbPromise = new Promise((resolve, reject) => {
    const request = indexedDB.open('SOMS_DB', 2);
    request.onupgradeneeded = (e) => {
        const db = e.target.result;
        if (!db.objectStoreNames.contains('data')) db.createObjectStore('data');
        if (!db.objectStoreNames.contains('sync_queue')) db.createObjectStore('sync_queue', { keyPath: 'id', autoIncrement: true });
    };
    request.onsuccess = (e) => resolve(e.target.result);
    request.onerror = (e) => reject(e.target.error);
});

async function dbGet(store, key) {
    const db = await dbPromise;
    return new Promise((resolve, reject) => {
        const trans = db.transaction(store, 'readonly');
        const req = trans.objectStore(store).get(key);
        req.onsuccess = () => resolve(req.result);
        req.onerror = () => reject(req.error);
    });
}

async function dbSet(store, key, value) {
    const db = await dbPromise;
    return new Promise((resolve, reject) => {
        const trans = db.transaction(store, 'readwrite');
        const req = trans.objectStore(store).put(value, key);
        req.onsuccess = () => resolve();
        req.onerror = () => reject(req.error);
    });
}

async function dbAdd(store, value) {
    const db = await dbPromise;
    return new Promise((resolve, reject) => {
        const trans = db.transaction(store, 'readwrite');
        const req = trans.objectStore(store).add(value);
        req.onsuccess = () => resolve();
        req.onerror = () => reject(req.error);
    });
}

async function dbGetAll(store) {
    const db = await dbPromise;
    return new Promise((resolve, reject) => {
        const trans = db.transaction(store, 'readonly');
        const req = trans.objectStore(store).getAll();
        req.onsuccess = () => resolve(req.result);
        req.onerror = () => reject(req.error);
    });
}

async function dbDelete(store, key) {
    const db = await dbPromise;
    return new Promise((resolve, reject) => {
        const trans = db.transaction(store, 'readwrite');
        const req = trans.objectStore(store).delete(key);
        req.onsuccess = () => resolve();
        req.onerror = () => reject(req.error);
    });
}

// --- App State ---
const state = {
    user: JSON.parse(localStorage.getItem('user')) || null,
    token: localStorage.getItem('token') || null,
};

const routes = {
    '/': homePage,
    '/login': loginPage,
    '/learners': learnersPage,
    '/assessments': assessmentsPage,
    '/events': eventsPage,
    '/collaboration': collaborationPage,
    '/leaderboard': leaderboardPage,
    '/super-admin': superAdminPage,
};

// --- Initialization ---
async function init() {
    window.addEventListener('hashchange', router);
    window.addEventListener('online', syncData);
    window.addEventListener('offline', () => updateOnlineStatus(false));
    
    updateOnlineStatus(navigator.onLine);
    router();
    updateNav();
    
    if (navigator.onLine) {
        syncData();
    }
}

function updateOnlineStatus(isOnline) {
    const indicator = document.getElementById('offline-indicator');
    if (indicator) {
        indicator.style.display = isOnline ? 'none' : 'block';
    }
}

async function syncData() {
    updateOnlineStatus(true);
    const queue = await dbGetAll('sync_queue');
    if (queue.length === 0) return;

    console.log('Syncing data...', queue.length, 'items');
    for (const item of queue) {
        try {
            await apiFetch(item.endpoint, {
                method: item.method,
                body: item.body
            }, true); // forceOnline = true
            await dbDelete('sync_queue', item.id);
        } catch (err) {
            console.error('Failed to sync item:', item, err);
            break; // Stop syncing if network fails again
        }
    }
}

function router() {
    const hash = window.location.hash || '#/';
    const path = hash.substring(1);
    
    if (!state.token && path !== '/login') {
        window.location.hash = '#/login';
        return;
    }

    const page = routes[path] || routes['/'];
    page();
}

function updateNav() {
    const navLinks = document.getElementById('nav-links');
    if (!navLinks) return;
    
    if (!state.token) {
        navLinks.innerHTML = `
            <li class="nav-item"><a class="nav-link" href="#/login">Login</a></li>
        `;
        return;
    }

    let html = `<li class="nav-item"><a class="nav-link" href="#/">Dashboard</a></li>`;
    
    if (state.user.role === 'Super Admin') {
        html += `<li class="nav-item"><a class="nav-link fw-bold text-warning" href="#/super-admin">Super Admin</a></li>`;
    }

    html += `
        <li class="nav-item"><a class="nav-link" href="#/learners">Learners</a></li>
        <li class="nav-item"><a class="nav-link" href="#/assessments">Assessments</a></li>
        <li class="nav-item"><a class="nav-link" href="#/events">Events</a></li>
        <li class="nav-item"><a class="nav-link" href="#/collaboration">Hub</a></li>
        <li class="nav-item"><a class="nav-link" href="#/leaderboard">Ranking</a></li>
        <li class="nav-item"><a class="nav-link text-danger" href="#" id="logout-btn">Logout</a></li>
    `;

    navLinks.innerHTML = html;

    document.getElementById('logout-btn').addEventListener('click', (e) => {
        e.preventDefault();
        logout();
    });
}

function logout() {
    localStorage.removeItem('token');
    localStorage.removeItem('user');
    state.token = null;
    state.user = null;
    window.location.hash = '#/login';
    updateNav();
}

async function apiFetch(endpoint, options = {}, forceOnline = false) {
    const url = API_URL + endpoint;
    const method = options.method || 'GET';
    const body = options.body || null;

    const defaultOptions = {
        headers: {
            'Content-Type': 'application/json',
            ...(state.token ? { 'Authorization': `Bearer ${state.token}` } : {})
        }
    };

    if (method === 'GET' && !forceOnline) {
        try {
            const response = await fetch(url, { ...defaultOptions, ...options });
            if (response.status === 401) { logout(); throw new Error('Unauthorized'); }
            const data = await response.json();
            if (!response.ok) throw new Error(data.error || 'API Error');
            
            // Save to offline storage
            await dbSet('data', endpoint, data);
            return data;
        } catch (err) {
            console.warn('Network failed, trying offline storage for:', endpoint);
            const cached = await dbGet('data', endpoint);
            if (cached) return cached;
            throw err;
        }
    } else {
        // POST/PUT/DELETE
        try {
            const response = await fetch(url, { ...defaultOptions, ...options });
            if (response.status === 401) { logout(); throw new Error('Unauthorized'); }
            const data = await response.json();
            if (!response.ok) throw new Error(data.error || 'API Error');
            return data;
        } catch (err) {
            if (forceOnline) throw err;
            
            console.warn('Network failed, queueing request for:', endpoint);
            await dbAdd('sync_queue', { endpoint, method, body, timestamp: Date.now() });
            
            // Return a "fake" success to keep the UI responsive
            return { success: true, offline: true, message: 'Data queued for sync' };
        }
    }
}

function render(html) {
    const content = document.getElementById('content');
    if (content) content.innerHTML = html;
}

// --- Page Renderers ---

async function homePage() {
    render(`
        <div class="p-4 mb-4 bg-white rounded-4 shadow-sm">
            <h1 class="h2 fw-bold">Welcome back, ${state.user.email}</h1>
            <p class="text-muted">You are logged in as <strong>${state.user.role}</strong>.</p>
            <hr class="my-4">
            <div class="row g-4">
                <div class="col-md-3">
                    <div class="card h-100 border-0 shadow-sm text-center p-3">
                        <i class="bi bi-people fs-1 text-primary mb-2"></i>
                        <h5 class="card-title">Learners</h5>
                        <a href="#/learners" class="btn btn-sm btn-outline-primary mt-auto">Manage</a>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card h-100 border-0 shadow-sm text-center p-3">
                        <i class="bi bi-journal-check fs-1 text-success mb-2"></i>
                        <h5 class="card-title">Assessments</h5>
                        <a href="#/assessments" class="btn btn-sm btn-outline-success mt-auto">Open Hub</a>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card h-100 border-0 shadow-sm text-center p-3">
                        <i class="bi bi-calendar-event fs-1 text-warning mb-2"></i>
                        <h5 class="card-title">Events</h5>
                        <a href="#/events" class="btn btn-sm btn-outline-warning mt-auto">Calendar</a>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card h-100 border-0 shadow-sm text-center p-3">
                        <i class="bi bi-trophy fs-1 text-info mb-2"></i>
                        <h5 class="card-title">Leaderboard</h5>
                        <a href="#/leaderboard" class="btn btn-sm btn-outline-info mt-auto">View Rankings</a>
                    </div>
                </div>
            </div>
        </div>
    `);
}

function loginPage() {
    render(`
        <div class="row justify-content-center">
            <div class="col-md-5">
                <div class="card shadow-lg border-0 rounded-4">
                    <div class="card-body p-5">
                        <h2 class="fw-bold text-center mb-4 text-primary"><i class="bi bi-mortarboard-fill me-2"></i>SOMS Platform</h2>
                        <form id="login-form">
                            <div class="mb-3">
                                <label class="form-label">Email</label>
                                <input type="email" id="email" class="form-control" placeholder="superadmin@system.com" required>
                            </div>
                            <div class="mb-4">
                                <label class="form-label">Password</label>
                                <input type="password" id="password" class="form-control" placeholder="password" required>
                            </div>
                            <button type="submit" class="btn btn-primary w-100 py-2 fw-bold shadow">Sign In</button>
                        </form>
                        <div class="mt-4 p-3 bg-light rounded-3 text-center text-muted small">
                            <strong>Demo Credentials</strong><br>
                            Super Admin: superadmin@system.com / password<br>
                            Admin: admin@sowetohigh.edu.za / password
                        </div>
                    </div>
                </div>
            </div>
        </div>
    `);

    document.getElementById('login-form').addEventListener('submit', async (e) => {
        e.preventDefault();
        const email = document.getElementById('email').value;
        const password = document.getElementById('password').value;

        try {
            const data = await apiFetch('/auth/login', {
                method: 'POST',
                body: JSON.stringify({ email, password })
            }, true); // forceOnline for login

            if (data.token) {
                localStorage.setItem('token', data.token);
                localStorage.setItem('user', JSON.stringify(data.user));
                state.token = data.token;
                state.user = data.user;
                updateNav();
                window.location.hash = '#/';
            }
        } catch (err) {
            alert('Login failed: ' + err.message);
        }
    });
}

async function superAdminPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const stats = await apiFetch('/schools/stats');
        const schools = await apiFetch('/schools');
        
        let html = `
            <div class="row mb-4">
                <div class="col">
                    <h2 class="fw-bold h3">Super Admin Console</h2>
                    <p class="text-muted">Global platform management</p>
                </div>
                <div class="col-auto">
                    <button class="btn btn-primary shadow">Onboard New School</button>
                </div>
            </div>

            <div class="row g-4 mb-5">
                <div class="col-md-3">
                    <div class="card p-3 border-0 shadow-sm text-center">
                        <div class="text-muted small mb-1">Total Schools</div>
                        <div class="h2 fw-bold text-primary">${stats.total_schools}</div>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card p-3 border-0 shadow-sm text-center">
                        <div class="text-muted small mb-1">Total Learners</div>
                        <div class="h2 fw-bold text-success">${stats.total_learners}</div>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card p-3 border-0 shadow-sm text-center">
                        <div class="text-muted small mb-1">System Uptime</div>
                        <div class="h2 fw-bold text-info">${stats.uptime}</div>
                    </div>
                </div>
                <div class="col-md-3">
                    <div class="card p-3 border-0 shadow-sm text-center">
                        <div class="text-muted small mb-1">Data Storage</div>
                        <div class="h2 fw-bold text-warning">${stats.storage}</div>
                    </div>
                </div>
            </div>

            <div class="card border-0 shadow-sm rounded-4">
                <div class="card-header bg-white py-3">
                    <h5 class="mb-0 fw-bold">Participating Schools</h5>
                </div>
                <div class="table-responsive">
                    <table class="table table-hover align-middle mb-0">
                        <thead>
                            <tr>
                                <th class="ps-4">Name</th>
                                <th>Province</th>
                                <th>District</th>
                                <th class="text-end pe-4">Actions</th>
                            </tr>
                        </thead>
                        <tbody>
        `;
        schools.forEach(s => {
            html += `
                <tr>
                    <td class="ps-4 fw-bold text-primary">${s.name}</td>
                    <td>${s.province}</td>
                    <td>${s.district}</td>
                    <td class="text-end pe-4">
                        <button class="btn btn-sm btn-outline-primary">Dashboard</button>
                    </td>
                </tr>
            `;
        });
        html += '</tbody></table></div></div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Access Denied: Super Admin only (or offline)</div>');
    }
}

async function learnersPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const learners = await apiFetch('/learners');
        let html = `
            <div class="d-flex justify-content-between align-items-center mb-4">
                <h2 class="fw-bold">Learners</h2>
                <button class="btn btn-primary btn-sm">Add New Learner</button>
            </div>
            <div class="table-responsive bg-white p-3 rounded-4 shadow-sm">
                <table class="table table-hover align-middle">
                    <thead>
                        <tr>
                            <th>Full Name</th>
                            <th>Grade</th>
                            <th>Student ID</th>
                            <th>Actions</th>
                        </tr>
                    </thead>
                    <tbody>
        `;
        learners.forEach(l => {
            html += `
                <tr>
                    <td>${l.full_name}</td>
                    <td><span class="badge bg-light text-dark">${l.grade}</span></td>
                    <td><code>${l.student_id}</code></td>
                    <td><button class="btn btn-sm btn-outline-secondary">Edit</button></td>
                </tr>
            `;
        });
        html += '</tbody></table></div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Failed to load learners</div>');
    }
}

async function assessmentsPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const assessments = await apiFetch('/assessments');
        let html = `
            <div class="d-flex justify-content-between align-items-center mb-4">
                <h2 class="fw-bold">Assessments</h2>
                <button class="btn btn-primary btn-sm">Create Assessment</button>
            </div>
            <div class="row g-3">
        `;
        assessments.forEach(a => {
            html += `
                <div class="col-md-4">
                    <div class="card shadow-sm border-0 rounded-4">
                        <div class="card-body">
                            <h5 class="card-title fw-bold">${a.title || a.name}</h5>
                            <h6 class="card-subtitle mb-3 text-muted">${a.subject || a.grade} — ${a.type}</h6>
                            <div class="d-grid">
                                <button class="btn btn-sm btn-primary">Record Marks</button>
                            </div>
                        </div>
                    </div>
                </div>
            `;
        });
        html += '</div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Failed to load assessments</div>');
    }
}

async function eventsPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const events = await apiFetch('/events');
        let html = `
            <div class="d-flex justify-content-between align-items-center mb-4">
                <h2 class="fw-bold">School Calendar</h2>
                <button class="btn btn-primary btn-sm">Add Event</button>
            </div>
            <div class="bg-white p-4 rounded-4 shadow-sm">
        `;
        if (events.length === 0) html += '<p class="text-muted text-center">No upcoming events.</p>';
        events.forEach(e => {
            html += `
                <div class="d-flex border-bottom py-3">
                    <div class="text-center me-4" style="min-width: 60px;">
                        <div class="h3 fw-bold mb-0">${new Date(e.start_datetime).getDate()}</div>
                        <div class="small text-uppercase text-muted">${new Date(e.start_datetime).toLocaleString('default', { month: 'short' })}</div>
                    </div>
                    <div>
                        <h5 class="mb-1 fw-bold">${e.title}</h5>
                        <p class="text-muted small mb-0"><i class="bi bi-clock"></i> ${new Date(e.start_datetime).toLocaleTimeString()} — ${e.location || 'No location'}</p>
                    </div>
                </div>
            `;
        });
        html += '</div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Failed to load events</div>');
    }
}

async function collaborationPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const resources = await apiFetch('/collaboration/resources');
        let html = `
            <div class="d-flex justify-content-between align-items-center mb-4">
                <h2 class="fw-bold">Collaboration Hub</h2>
                <button class="btn btn-primary btn-sm">Share Resource</button>
            </div>
            <div class="row g-4">
        `;
        resources.forEach(r => {
            html += `
                <div class="col-md-6">
                    <div class="card h-100 border-0 shadow-sm rounded-4">
                        <div class="card-body">
                            <div class="d-flex justify-content-between">
                                <h5 class="fw-bold mb-1">${r.title}</h5>
                                ${r.is_public == 1 ? '<span class="badge bg-success">Public</span>' : '<span class="badge bg-secondary">School Only</span>'}
                            </div>
                            <p class="text-muted small mb-3">${r.description}</p>
                            <div class="d-flex align-items-center text-muted small">
                                <i class="bi bi-person-circle me-2"></i> ${r.teacher_email}
                            </div>
                        </div>
                        <div class="card-footer bg-transparent border-0 text-end">
                            <button class="btn btn-link btn-sm text-decoration-none">Download</button>
                        </div>
                    </div>
                </div>
            `;
        });
        html += '</div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Failed to load resources</div>');
    }
}

async function leaderboardPage() {
    render('<div class="text-center p-5"><div class="spinner-border text-primary"></div></div>');
    try {
        const rankings = await apiFetch('/leaderboard');
        let html = `
            <h2 class="fw-bold mb-4">Student Rankings</h2>
            <div class="bg-white p-3 rounded-4 shadow-sm">
                <table class="table table-hover align-middle">
                    <thead>
                        <tr>
                            <th width="80">Rank</th>
                            <th>Learner</th>
                            <th>Performance</th>
                            <th class="text-end">Average</th>
                        </tr>
                    </thead>
                    <tbody>
        `;
        rankings.forEach((r, index) => {
            const color = index === 0 ? 'text-warning' : (index === 1 ? 'text-secondary' : (index === 2 ? 'text-brown' : ''));
            html += `
                <tr>
                    <td class="h4 fw-bold ${color}">#${index + 1}</td>
                    <td><div class="fw-bold">${r.full_name}</div></td>
                    <td>
                        <div class="progress" style="height: 10px;">
                            <div class="progress-bar bg-primary" style="width: ${r.average_percent}%"></div>
                        </div>
                    </td>
                    <td class="text-end fw-bold">${parseFloat(r.average_percent).toFixed(1)}%</td>
                </tr>
            `;
        });
        html += '</tbody></table></div>';
        render(html);
    } catch (err) {
        render('<div class="alert alert-danger">Failed to load leaderboard</div>');
    }
}

init();