// IndexedDB Konfiguration
const DB_NAME = 'mediCustomersDB';
const DB_VERSION = 1;
const STORE_NAME = 'customers';

// Datenbank initialisieren
const initDB = () => {
    return new Promise((resolve, reject) => {
        const request = indexedDB.open(DB_NAME, DB_VERSION);
        
        request.onerror = () => {
            console.error('Fehler beim Öffnen der Datenbank:', request.error);
            reject(request.error);
        };
        
        request.onsuccess = () => {
            console.log('Datenbank erfolgreich geöffnet');
            resolve(request.result);
        };
        
        request.onupgradeneeded = (event) => {
            const db = event.target.result;
            if (!db.objectStoreNames.contains(STORE_NAME)) {
                const store = db.createObjectStore(STORE_NAME, { keyPath: 'nummer' });
                // Indizes für die Suche erstellen
                store.createIndex('name', 'name', { unique: false });
                store.createIndex('ort', 'ort', { unique: false });
                store.createIndex('plz', 'plz', { unique: false });
                store.createIndex('fachrichtung', 'fachrichtung', { unique: false });
            }
        };
    });
};

// Kunden in IndexedDB speichern
const saveCustomers = async (customers) => {
    const db = await initDB();
    const tx = db.transaction(STORE_NAME, 'readwrite');
    const store = tx.objectStore(STORE_NAME);
    
    return Promise.all(customers.map(customer => {
        return new Promise((resolve, reject) => {
            const request = store.put(customer);
            request.onsuccess = () => resolve();
            request.onerror = () => reject(request.error);
        });
    }));
};

// Kunden aus IndexedDB suchen
const searchCustomersOffline = async (searchParams) => {
    const db = await initDB();
    const tx = db.transaction(STORE_NAME, 'readonly');
    const store = tx.objectStore(STORE_NAME);
    
    return new Promise((resolve, reject) => {
        const request = store.getAll();
        
        request.onsuccess = () => {
            let results = request.result;
            
            // Filtern basierend auf den Suchparametern
            if (searchParams.q) {
                const searchTerms = searchParams.q.toLowerCase().split(' ');
                const operator = searchParams.operator || 'or';
                
                results = results.filter(customer => {
                    const searchableText = `${customer.name} ${customer.ort} ${customer.nummer} ${customer.plz} ${customer.fachrichtung}`.toLowerCase();
                    
                    if (operator === 'and') {
                        return searchTerms.every(term => searchableText.includes(term));
                    } else {
                        return searchTerms.some(term => searchableText.includes(term));
                    }
                });
            }
            
            // Spezifische Feldsuche
            if (searchParams.name) {
                results = results.filter(c => c.name.toLowerCase().includes(searchParams.name.toLowerCase()));
            }
            if (searchParams.ort) {
                results = results.filter(c => c.ort.toLowerCase().includes(searchParams.ort.toLowerCase()));
            }
            if (searchParams.nummer) {
                results = results.filter(c => c.nummer.toString().includes(searchParams.nummer));
            }
            if (searchParams.plz) {
                results = results.filter(c => c.plz.includes(searchParams.plz));
            }
            if (searchParams.fachrichtung) {
                results = results.filter(c => c.fachrichtung.toLowerCase().includes(searchParams.fachrichtung.toLowerCase()));
            }
            
            resolve(results);
        };
        
        request.onerror = () => {
            reject(request.error);
        };
    });
};

// Synchronisationsstatus speichern
const syncStatus = {
    lastSync: null,
    isOnline: navigator.onLine
};

// Event Listener für Online/Offline Status
window.addEventListener('online', () => {
    syncStatus.isOnline = true;
    document.body.classList.remove('offline');
    synchronizeData();
});

window.addEventListener('offline', () => {
    syncStatus.isOnline = false;
    document.body.classList.add('offline');
});

// Daten mit dem Server synchronisieren
const synchronizeData = async () => {
    if (!syncStatus.isOnline) return;
    
    try {
        const response = await fetch('/api/customers');
        const customers = await response.json();
        await saveCustomers(customers);
        syncStatus.lastSync = new Date();
        console.log('Daten erfolgreich synchronisiert');
    } catch (error) {
        console.error('Fehler bei der Synchronisation:', error);
    }
};

// Export der Funktionen
window.dbHelper = {
    initDB,
    saveCustomers,
    searchCustomersOffline,
    synchronizeData,
    syncStatus
};