// Admin Overview — the Admin area's landing page. An ops/health board (distinct
// from the user Dashboard, which is app-centric): it summarises updates,
// backups, SSH/security and system health from data we already generate, and
// each card links to where you act on it. Renders into #config-section.
class AdminOverview {
    constructor(rootId = 'config-section') {
        this.rootId = rootId;
        this.taskManager = (typeof TaskManager !== 'undefined') ? new TaskManager() : null;
        this._bound = false;
    }

    root() { return document.getElementById(this.rootId); }

    async init() {
        const r = this.root();
        if (r) r.innerHTML = '<div class="admin-page"><div class="backup-empty-state">Loading…</div></div>';
        this.bindEvents();
        const [upd, backup, ssh, disk, mem, info] = await Promise.all([
            this.fetchJson('/data/system/update_status.json'),
            this.fetchJson('/data/backup/generated/dashboard.json'),
            this.fetchJson('/data/ssh/access.json'),
            this.fetchJson('/data/system/disk_usage.json'),
            this.fetchJson('/data/system/memory_usage.json'),
            this.fetchJson('/data/system/system_info.json')
        ]);
        this.d = { upd, backup, ssh, disk, mem, info };
        this.render();
    }

    async fetchJson(url) {
        try { const r = await fetch(`${url}?t=${Date.now()}`); if (!r.ok) return null; return await r.json(); }
        catch { return null; }
    }

    escape(s) {
        return String(s ?? '').replace(/[&<>"']/g, c => (
            { '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' }[c]
        ));
    }

    notify(msg, type) {
        if (window.notificationSystem) window.notificationSystem.show(msg, type || 'info');
        else console.log(`[admin ${type || 'info'}] ${msg}`);
    }

    bindEvents() {
        if (this._bound) return;
        this._bound = true;
        document.addEventListener('click', (e) => {
            const go = e.target.closest('[data-admin-go]');
            if (go) { this.go(go.dataset.adminGo); return; }
            if (e.target.closest('[data-admin-update]')) { this.runUpdate(); return; }
        });
    }

    go(where) {
        if (where === 'backup') {
            window.librePortalSPA?.navigate('/backup', true);
        } else if (where === 'ssh' || where === 'security' || where === 'system') {
            const target = where === 'ssh' ? 'ssh-access' : where;
            window.history.pushState({}, '', window.adminPath(target));
            window.configCategory = target;
            window.configManager?.renderConfig?.(target);
        }
    }

    async runUpdate() {
        if (!this.taskManager) { this.notify('Task system unavailable', 'error'); return; }
        if (!confirm('Update LibrePortal now? The WebUI may restart briefly.')) return;
        try { await this.taskManager.createTask('libreportal update apply', 'update', null); }
        catch (e) { this.notify(`Failed to start update: ${e.message || e}`, 'error'); }
    }

    /* A status card: kind sets the dot colour (ok/warn/none). actionsHtml is
       the footer (Manage link / button). */
    card(title, kind, lines, actionsHtml) {
        return `
            <div class="admin-card">
                <div class="admin-card-head">
                    <span class="admin-card-title">${this.escape(title)}</span>
                    <span class="admin-status-dot ${kind}"></span>
                </div>
                <div class="admin-card-body">${lines}</div>
                <div class="admin-card-actions">${actionsHtml || ''}</div>
            </div>`;
    }

    line(label, value) {
        return `<div class="admin-card-line"><span>${this.escape(label)}</span><strong>${this.escape(value)}</strong></div>`;
    }

    render() {
        const root = this.root();
        if (!root) return;
        const d = this.d || {};

        // Updates
        const upd = d.upd || {};
        const updAvail = upd.update_available === true;
        const updCard = this.card(
            'Updates',
            updAvail ? 'warn' : 'ok',
            updAvail
                ? this.line('Status', 'Update available') + this.line('Current → latest', `${upd.current_version || '?'} → ${upd.latest_version || '?'}`)
                : this.line('Status', 'Up to date') + this.line('Version', upd.current_version || '—'),
            updAvail && upd.can_update
                ? `<button type="button" class="backup-primary-btn" data-admin-update>Update now</button>`
                : `<span class="admin-card-ok">Nothing to do</span>`
        );

        // Backups
        const b = d.backup || {};
        const apps = Array.isArray(b.apps) ? b.apps : [];
        const locs = Array.isArray(b.locations) ? b.locations : [];
        const protectedApps = apps.filter(a => a.latest_snapshot).length;
        const totalSize = locs.reduce((a, r) => a + (parseInt(r.total_size_bytes) || 0), 0);
        const noBackups = apps.length && protectedApps === 0;
        const backupCard = this.card(
            'Backups',
            !locs.length ? 'none' : (noBackups ? 'warn' : 'ok'),
            this.line('Apps protected', `${protectedApps} / ${apps.length}`)
                + this.line('Locations', String(locs.length))
                + this.line('Stored', this.bytes(totalSize)),
            `<button type="button" class="backup-secondary-btn" data-admin-go="backup">Manage backups →</button>`
        );

        // SSH & Security
        const s = d.ssh || {};
        const keyCount = Array.isArray(s.keys) ? s.keys.length : 0;
        const pwOn = s.password_auth === true;
        // Warn when password login is on AND no keys (the weakest posture).
        const sshKind = (pwOn && keyCount === 0) ? 'warn' : 'ok';
        const sshCard = this.card(
            'SSH & Security',
            sshKind,
            this.line('Password login', pwOn ? 'On' : 'Key-only')
                + this.line('Authorized keys', String(keyCount))
                + this.line('Login user', s.user || '—'),
            `<button type="button" class="backup-secondary-btn" data-admin-go="ssh">Manage SSH access →</button>`
        );

        // System health
        const disk = d.disk?.root || {};
        const mem = d.mem || {};
        const info = d.info || {};
        const diskPct = parseInt(disk.percent) || 0;
        const sysKind = diskPct >= 90 ? 'warn' : 'ok';
        const sysCard = this.card(
            'System',
            sysKind,
            this.line('Disk', disk.text || `${diskPct}%`)
                + this.line('Memory', mem.text || '—')
                + this.line('Uptime', (info.uptime || '—').replace(/^up /, ''))
                + this.line('OS', info.os || '—'),
            `<button type="button" class="backup-secondary-btn" data-admin-go="system">View system stats →</button>`
        );

        root.innerHTML = `
            <div class="admin-page">
                <div class="page-header config-page-header">
                    <div class="page-header-title">
                        <div class="admin-breadcrumb">Admin</div>
                        <h1>Overview</h1>
                        <p>System health and admin status at a glance. Manage anything from the cards below.</p>
                    </div>
                </div>
                <div class="admin-card-grid">
                    ${updCard}
                    ${backupCard}
                    ${sshCard}
                    ${sysCard}
                </div>
            </div>`;
    }

    bytes(n) {
        n = parseInt(n) || 0;
        const u = ['B', 'KB', 'MB', 'GB', 'TB'];
        let i = 0;
        while (n >= 1024 && i < u.length - 1) { n /= 1024; i++; }
        return `${n.toFixed(i ? 1 : 0)} ${u[i]}`;
    }
}

window.AdminOverview = AdminOverview;