/**
 * alerts-controller.js - Notification Management with Acknowledgement
 * ===================================================================
 * Handles polling, rendering, and acknowledging system alerts.
 * * Hardened for Enterprise MVC:
 * - Uses central `apiFetch` to automatically inherit HTTP-Only Cookies and CSRF headers.
 * - Relies on `fetch-wrapper.js` for 401 session expiration handling.
 * - Uses `SecurityUtils` for XSS-safe DOM generation.
 */

(function() {
    'use strict';

    // Safe HTML Escaping (Fallback to native if SecurityUtils isn't loaded yet)
    const escapeHTML = (text) => {
        if (window.SecurityUtils) return window.SecurityUtils.escapeHTML(text);
        const div = document.createElement('div');
        div.textContent = text;
        return div.innerHTML;
    };

    // ── Data Fetching ───────────────────────────────────────────────────────
    async function loadAlerts() {
        // Only fetch if user is authenticated (UI hint check)
        const user = JSON.parse(localStorage.getItem('user') || 'null');
        if (!user || (!user.email && !user.temp)) return;

        try {
            // Enterprise Architecture: Centralized apiFetch handles CSRF, Cookies, and 401s automatically
            const data = await window.apiFetch('/alerts?limit=20');

            if (data.success) {
                renderAlerts(data.alerts || []);
                // Ensure we only count unacknowledged alerts for the badge
                const unread = data.alerts ? data.alerts.filter(a => !a.acknowledged).length : 0;
                updateBadgeCount(unread);
            }
        } catch (error) {
            // Silently fail for background polling to prevent spamming the user,
            // but log for debugging purposes.
            console.error('[Alerts] Background sync failed:', error);
        }
    }

    // ── Rendering ───────────────────────────────────────────────────────────
    function renderAlerts(alerts) {
        const list = document.querySelector('.notifications-list');
        if (!list) return;

        if (alerts.length === 0) {
            list.innerHTML = '<p class="empty-message" style="padding:1.5rem;text-align:center;color:var(--md-on-surface-muted);font-size:0.85rem;">No new alerts</p>';
            return;
        }

        list.innerHTML = alerts.map(alert => `
            <div class="notification-item ${alert.acknowledged ? 'acknowledged' : ''}" data-alert-id="${escapeHTML(alert._id)}">
                <span class="notification-icon">${getSeverityIcon(alert.severity)}</span>
                <div class="notification-content">
                    <p class="notification-title">${escapeHTML(alert.message)}</p>
                    <p class="notification-time">${escapeHTML(formatTimeAgo(alert.created_at))}</p>
                </div>
                ${!alert.acknowledged ? `
                    <button class="notification-ack-btn" data-alert-id="${escapeHTML(alert._id)}" title="Mark as read">
                        <span class="material-symbols-rounded">check</span>
                    </button>
                ` : ''}
            </div>
        `).join('');

        list.querySelectorAll('.notification-ack-btn').forEach(btn => {
            btn.addEventListener('click', (e) => {
                e.stopPropagation();
                acknowledgeAlert(btn.dataset.alertId);
            });
        });
    }

    async function acknowledgeAlert(alertId) {
        try {
            // Use apiFetch so CSRF headers are automatically injected
            const data = await window.apiFetch(`/alerts/${alertId}`, { method: 'PUT' });

            if (data.success) {
                const el = document.querySelector(`[data-alert-id="${alertId}"]`);
                if (el) {
                    el.style.opacity = '0';
                    el.style.transform = 'translateX(20px)';
                    el.style.transition = '0.3s ease';
                    setTimeout(() => {
                        el.remove();
                        loadAlerts(); // Refresh to update count and get fresh data
                    }, 300);
                }
            }
        } catch (error) {
            console.error('[Alerts] Ack failed:', error);
            if (window.ErrorHandler) {
                window.ErrorHandler.showError(error);
            } else if (window.SecurityUtils) {
                window.SecurityUtils.showToast('Failed to acknowledge alert', 'error');
            }
        }
    }

    // ── Utilities ───────────────────────────────────────────────────────────
    function updateBadgeCount(count) {
        const badge = document.getElementById('notification-count');
        if (!badge) return;
        badge.textContent = count > 99 ? '99+' : count;
        badge.hidden = (count <= 0);
    }

    function getSeverityIcon(sev) {
        const icons = {
            'critical': ['warning', 'var(--md-error)'],
            'high': ['error', 'var(--md-error)'],
            'warning': ['info', 'var(--md-warning)'],
            'medium': ['info', 'var(--md-warning)']
        };
        const [icon, color] = icons[sev.toLowerCase()] || ['notifications', 'var(--md-on-surface-muted)'];
        return `<span class="material-symbols-rounded" style="color:${color}">${icon}</span>`;
    }

    function formatTimeAgo(dateStr) {
        if (!dateStr) return 'Unknown';
        const date = new Date(dateStr);
        if (isNaN(date.getTime())) return 'Unknown';
        
        const seconds = Math.floor((Date.now() - date.getTime()) / 1000);
        if (seconds < 60) return 'Just now';
        if (seconds < 3600) return `${Math.floor(seconds / 60)}m ago`;
        if (seconds < 86400) return `${Math.floor(seconds / 3600)}h ago`;
        return `${Math.floor(seconds / 86400)}d ago`;
    }

    // ── Initialization & Lifecycle ──────────────────────────────────────────
    function init() {
        // Prevent Multiple Polling Intervals (Memory Leak Guard for SPAs)
        if (window.AlertsController && window.AlertsController._poll) {
            clearInterval(window.AlertsController._poll);
        }

        // Only begin polling if user is authenticated
        const user = JSON.parse(localStorage.getItem('user') || 'null');
        if (!user || (!user.email && !user.temp)) {
            console.info('[Alerts] User not authenticated. Alerts polling disabled.');
            return;
        }

        loadAlerts();
        // 30s polling interval
        const _poll = setInterval(loadAlerts, 30000);

        // Expose globally to allow manual refresh and clean teardown
        window.AlertsController = {
            reload: loadAlerts,
            _poll: _poll,
            stop: () => clearInterval(_poll)
        };
        
        console.log('✅ Qualora Alerts Controller Initialized');
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', init);
    } else {
        init();
    }
})();