/**
 * MobileApp Service Worker
 * Provides caching for PWA shell, assets, and offline workorder support.
 */

const CACHE_NAME = 'xinon-mobile-v2';
const ASSETS_TO_CACHE = [
    '/MobileApp',
    '/mobile/app.js',
    '/mobile/shared/auth.js',
    '/mobile/shared/api.js',
    '/mobile/shared/base.css',
    '/mobile/shared/db.js',
    '/mobile/shared/offlineSettings.js',
    '/mobile/shared/syncQueue.js',
    '/mobile/shared/workorderOfflineService.js',
    '/mobile/shared/photoQueue.js',
    '/mobile/shared/syncManager.js',
    '/mobile/components/LoginScreen.js',
    '/mobile/components/MainMenu.js',
    '/mobile/components/OfflineIndicator.js',
    '/mobile/components/SyncStatus.js',
    '/mobile/modules/lager/LagerModule.js',
    '/mobile/modules/lager/inventur/StocktakeList.js',
    '/mobile/modules/lager/inventur/Scanner.js',
    '/mobile/modules/workorder/WorkorderModule.js',
    '/assets/images/xinon-full-transparent.png',
    '/assets/images/xinon-full-transparent-white.png',
    '/assets/images/xinon-sm.png'
];

// Workorder API endpoints that can be served from cache
const WORKORDER_CACHEABLE_ENDPOINTS = [
    '/MobileApp/Workorder/Workorder/get',
    '/MobileApp/Workorder/Workorder/getWorkorder',
    '/MobileApp/Workorder/Workorder/getWorkorderDetail',
    '/MobileApp/Workorder/Workorder/getDocumentation',
    '/MobileApp/Workorder/Workorder/getChecklist',
    '/MobileApp/Workorder/Workorder/getTenantConfig'
];

// Install: cache assets
self.addEventListener('install', (event) => {
    console.log('[SW] Installing...');
    event.waitUntil(
        caches.open(CACHE_NAME)
            .then(cache => cache.addAll(ASSETS_TO_CACHE))
            .then(() => {
                console.log('[SW] Assets cached');
                return self.skipWaiting();
            })
            .catch(err => {
                console.error('[SW] Cache failed:', err);
            })
    );
});

// Activate: clean old caches
self.addEventListener('activate', (event) => {
    console.log('[SW] Activating...');
    event.waitUntil(
        caches.keys().then(cacheNames => {
            return Promise.all(
                cacheNames
                    .filter(name => name.startsWith('xinon-mobile-') && name !== CACHE_NAME)
                    .map(name => {
                        console.log('[SW] Deleting old cache:', name);
                        return caches.delete(name);
                    })
            );
        }).then(() => self.clients.claim())
    );
});

// Fetch: handle requests with offline support
self.addEventListener('fetch', (event) => {
    const url = new URL(event.request.url);

    // Only handle same-origin requests
    if (url.origin !== location.origin) return;

    // Handle workorder API requests specially
    if (url.pathname.startsWith('/MobileApp/Workorder/')) {
        event.respondWith(handleWorkorderRequest(event.request, url));
        return;
    }

    // Other API calls: network only (no caching)
    if (url.pathname.startsWith('/MobileApp/') &&
        url.pathname !== '/MobileApp' &&
        url.pathname !== '/MobileApp/') {
        return;
    }

    // Static assets: cache-first with background update
    if (event.request.method === 'GET') {
        event.respondWith(handleAssetRequest(event.request, url));
    }
});

/**
 * Handle workorder API requests with offline fallback
 */
async function handleWorkorderRequest(request, url) {
    const isGet = request.method === 'GET';
    const isPost = request.method === 'POST';
    const endpoint = url.pathname;

    // Check if offline mode is enabled via message or localStorage check
    const offlineEnabled = await isOfflineModeEnabled();

    // For GET requests to cacheable endpoints
    if (isGet && WORKORDER_CACHEABLE_ENDPOINTS.some(ep => endpoint.startsWith(ep))) {
        try {
            // Try network first
            const response = await fetch(request);
            if (response.ok && offlineEnabled) {
                // Cache successful response for offline use
                const cache = await caches.open(CACHE_NAME + '-api');
                cache.put(request, response.clone());
            }
            return response;
        } catch (error) {
            // Network failed, try cache
            if (offlineEnabled) {
                const cached = await caches.match(request);
                if (cached) {
                    console.log('[SW] Serving from cache:', endpoint);
                    return cached;
                }
            }
            // Return offline error response
            return new Response(JSON.stringify({
                success: false,
                error: 'Offline - keine gecachten Daten',
                offline: true
            }), {
                status: 503,
                headers: { 'Content-Type': 'application/json' }
            });
        }
    }

    // For POST requests (mutations) - let them through, main thread handles queueing
    if (isPost) {
        try {
            return await fetch(request);
        } catch (error) {
            // Network error - return error response
            // The main thread WorkorderOfflineService handles queueing
            return new Response(JSON.stringify({
                success: false,
                error: 'Netzwerkfehler',
                networkError: true
            }), {
                status: 503,
                headers: { 'Content-Type': 'application/json' }
            });
        }
    }

    // Default: try network
    return fetch(request);
}

/**
 * Handle static asset requests with cache-first strategy
 */
async function handleAssetRequest(request, url) {
    const cached = await caches.match(request);

    if (cached) {
        // Return cached, update in background
        fetch(request).then(response => {
            if (response.ok) {
                caches.open(CACHE_NAME).then(cache => {
                    cache.put(request, response);
                });
            }
        }).catch(() => {});
        return cached;
    }

    // Not cached, fetch from network
    try {
        const response = await fetch(request);
        if (response.ok && url.origin === location.origin) {
            const cache = await caches.open(CACHE_NAME);
            cache.put(request, response.clone());
        }
        return response;
    } catch (error) {
        // Return offline page or error
        return new Response('Offline', { status: 503 });
    }
}

/**
 * Check if offline mode is enabled
 * This is a simplified check - the main thread handles the full logic
 */
async function isOfflineModeEnabled() {
    // Try to get from clients
    const clients = await self.clients.matchAll();
    for (const client of clients) {
        // Ask client for offline status
        // For now, assume enabled if we have cached API data
        const apiCache = await caches.open(CACHE_NAME + '-api');
        const keys = await apiCache.keys();
        return keys.length > 0;
    }
    return false;
}

// Background Sync event (Chrome/Edge only)
self.addEventListener('sync', (event) => {
    console.log('[SW] Background sync triggered:', event.tag);

    if (event.tag === 'workorder-sync') {
        event.waitUntil(handleBackgroundSync());
    }
});

/**
 * Handle background sync
 * Notify main thread to process sync queue
 */
async function handleBackgroundSync() {
    const clients = await self.clients.matchAll({ type: 'window' });

    for (const client of clients) {
        client.postMessage({
            type: 'BACKGROUND_SYNC',
            tag: 'workorder-sync'
        });
    }
}

// Message handler for communication with main thread
self.addEventListener('message', (event) => {
    const { type, data } = event.data || {};

    switch (type) {
        case 'SKIP_WAITING':
            self.skipWaiting();
            break;

        case 'CLEAR_API_CACHE':
            caches.delete(CACHE_NAME + '-api').then(() => {
                console.log('[SW] API cache cleared');
                event.ports[0]?.postMessage({ success: true });
            });
            break;

        case 'CACHE_WORKORDER_DATA':
            // Cache workorder data from main thread
            if (data && data.url && data.response) {
                caches.open(CACHE_NAME + '-api').then(cache => {
                    const response = new Response(JSON.stringify(data.response), {
                        headers: { 'Content-Type': 'application/json' }
                    });
                    cache.put(data.url, response);
                    console.log('[SW] Cached workorder data:', data.url);
                });
            }
            break;

        case 'GET_CACHE_STATUS':
            getCacheStatus().then(status => {
                event.ports[0]?.postMessage(status);
            });
            break;

        default:
            console.log('[SW] Unknown message type:', type);
    }
});

/**
 * Get cache status for debugging
 */
async function getCacheStatus() {
    const assetCache = await caches.open(CACHE_NAME);
    const apiCache = await caches.open(CACHE_NAME + '-api');

    const assetKeys = await assetCache.keys();
    const apiKeys = await apiCache.keys();

    return {
        cacheName: CACHE_NAME,
        assetsCached: assetKeys.length,
        apiCached: apiKeys.length,
        apiEndpoints: apiKeys.map(k => new URL(k.url).pathname)
    };
}

// Periodic sync (if supported - experimental)
self.addEventListener('periodicsync', (event) => {
    if (event.tag === 'workorder-periodic-sync') {
        console.log('[SW] Periodic sync triggered');
        event.waitUntil(handleBackgroundSync());
    }
});