// management/static/js/main.js
// -*- coding: utf-8 -*-

// VAPID_PUBLIC_KEY will be passed from the Django template.
// This is a placeholder; it will be filled with the correct value in the HTML file.
const VAPID_PUBLIC_KEY_PLACEHOLDER = "{{ vapid_public_key }}";

/**
 * Converts a base64 string to a Uint8Array.
 * @param {string} base64String
 * @returns {Uint8Array}
 */
function urlBase64ToUint8Array(base64String) {
    const padding = '='.repeat((4 - base64String.length % 4) % 4);
    const base64 = (base64String + padding)
        .replace(/\-/g, '+')
        .replace(/_/g, '/');
    const rawData = window.atob(base64);
    const outputArray = new Uint8Array(rawData.length);
    for (let i = 0; i < rawData.length; ++i) {
        outputArray[i] = rawData.charCodeAt(i);
    }
    return outputArray;
}

/**
 * Registers the service worker for the PWA.
 * @returns {Promise<ServiceWorkerRegistration|null>}
 */
async function registerServiceWorker() {
    if ('serviceWorker' in navigator) {
        try {
            const registration = await navigator.serviceWorker.register('/service-worker.js');
            console.log('Service worker registered successfully.');
            return registration;
        } catch (error) {
            console.error('Service worker registration failed:', error);
            return null;
        }
    }
    console.error('Service workers are not supported in this browser.');
    return null;
}

/**
 * Subscribes the user to push notifications.
 * @param {ServiceWorkerRegistration} registration
 */
async function subscribeUserToPush(registration) {
    if (!('PushManager' in window)) {
        console.error('Push notifications are not supported.');
        return;
    }

    if (!VAPID_PUBLIC_KEY_PLACEHOLDER || VAPID_PUBLIC_KEY_PLACEHOLDER === "YOUR_VAPID_PUBLIC_KEY_HERE") {
        console.error("VAPID public key not configured.");
        return;
    }

    try {
        const subscription = await registration.pushManager.subscribe({
            userVisibleOnly: true,
            applicationServerKey: urlBase64ToUint8Array(VAPID_PUBLIC_KEY_PLACEHOLDER)
        });

        console.log('User is subscribed to push.');
        const response = await fetch('/api/push/subscribe/', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'X-CSRFToken': document.querySelector('[name=csrfmiddlewaretoken]').value
            },
            body: JSON.stringify(subscription)
        });

        if (!response.ok) {
            console.error('Failed to save push subscription on server.');
        }

    } catch (error) {
        console.error('Push subscription failed:', error);
    }
}

/**
 * Fetches and displays user dashboard data from the API.
 */
async function fetchDashboardData() {
    try {
        const response = await fetch('/api/dashboard/');
        if (!response.ok) {
            throw new Error('Network response was not ok');
        }
        const data = await response.json();
        document.getElementById('username-display').textContent = data.username;
        document.getElementById('service-status').textContent = data.service_status;
        document.getElementById('used-traffic').textContent = (data.used_traffic / (1024 ** 3)).toFixed(2) + ' GB';
        document.getElementById('total-traffic').textContent = (data.total_traffic / (1024 ** 3)).toFixed(2) + ' GB';

        const configsList = document.getElementById('configs-list');
        configsList.innerHTML = ''; // Clear previous content
        data.configs.forEach(config => {
            const listItem = document.createElement('li');
            listItem.className = 'bg-gray-50 rounded-md p-3 border border-gray-200';
            listItem.innerHTML = `
                <div class="font-bold text-gray-800">${config.remark}</div>
                <div class="text-sm text-gray-500 break-all">${config.link}</div>
            `;
            configsList.appendChild(listItem);
        });

    } catch (error) {
        console.error('Error fetching dashboard data:', error);
        document.body.innerHTML = '<p class="text-red-500 text-center">خطا در بارگذاری اطلاعات داشبورد.</p>';
    }
}

/**
 * Handles the generation of the Telegram security token.
 */
async function handleTelegramTokenGeneration() {
    const generateTokenBtn = document.getElementById('generate-token-btn');
    const tokenDisplayArea = document.getElementById('token-display-area');
    const telegramTokenCode = document.getElementById('telegram-token');

    if (!generateTokenBtn) return;

    generateTokenBtn.addEventListener('click', async () => {
        const response = await fetch('/api/telegram/generate-token/', {
            method: 'POST',
            headers: {
                'X-CSRFToken': document.querySelector('[name=csrfmiddlewaretoken]').value
            }
        });
        if (response.ok) {
            const data = await response.json();
            telegramTokenCode.textContent = data.token;
            tokenDisplayArea.classList.remove('hidden');
        } else {
            // Using a custom modal or message box instead of alert()
            console.error('Failed to generate token.');
            alert('خطا در تولید توکن.');
        }
    });
}

document.addEventListener('DOMContentLoaded', async () => {
    // Fetch and render dashboard data
    await fetchDashboardData();

    // PWA and Push Notification logic
    const registration = await registerServiceWorker();
    if (registration) {
        if (Notification.permission === 'granted') {
            console.log('Push permission already granted.');
        } else if (Notification.permission === 'denied') {
            console.log('Push permission denied by user.');
        } else {
            // Prompt the user for permission
            // This is a browser feature, so we don't need a custom modal
            Notification.requestPermission().then(permission => {
                if (permission === 'granted') {
                    subscribeUserToPush(registration);
                } else {
                    console.log('User denied push notification permission.');
                }
            });
        }
    }

    // Telegram token generation
    handleTelegramTokenGeneration();
});