/* Mini IndexedDB Wrapper für die PWA.
 * Speichert: Auth-Token, Offline-Queue für Uploads.
 */
(function () {
    const DB_NAME = 'baustelle-pwa-v1';
    const DB_VERSION = 1;
    let dbPromise = null;

    function open() {
        if (dbPromise) return dbPromise;
        dbPromise = new Promise((resolve, reject) => {
            const req = indexedDB.open(DB_NAME, DB_VERSION);
            req.onupgradeneeded = () => {
                const db = req.result;
                if (!db.objectStoreNames.contains('kv')) {
                    db.createObjectStore('kv');
                }
                if (!db.objectStoreNames.contains('queue')) {
                    db.createObjectStore('queue', { keyPath: 'id', autoIncrement: true });
                }
            };
            req.onsuccess = () => resolve(req.result);
            req.onerror = () => reject(req.error);
        });
        return dbPromise;
    }

    async function get(key) {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('kv', 'readonly');
            const r = tx.objectStore('kv').get(key);
            r.onsuccess = () => res(r.result);
            r.onerror = () => rej(r.error);
        });
    }

    async function set(key, val) {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('kv', 'readwrite');
            tx.objectStore('kv').put(val, key);
            tx.oncomplete = () => res();
            tx.onerror = () => rej(tx.error);
        });
    }

    async function del(key) {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('kv', 'readwrite');
            tx.objectStore('kv').delete(key);
            tx.oncomplete = () => res();
            tx.onerror = () => rej(tx.error);
        });
    }

    async function queuePush(item) {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('queue', 'readwrite');
            const r = tx.objectStore('queue').add(item);
            r.onsuccess = () => res(r.result);
            r.onerror = () => rej(r.error);
        });
    }

    async function queueAll() {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('queue', 'readonly');
            const r = tx.objectStore('queue').getAll();
            r.onsuccess = () => res(r.result || []);
            r.onerror = () => rej(r.error);
        });
    }

    async function queueDelete(id) {
        const db = await open();
        return new Promise((res, rej) => {
            const tx = db.transaction('queue', 'readwrite');
            tx.objectStore('queue').delete(id);
            tx.oncomplete = () => res();
            tx.onerror = () => rej(tx.error);
        });
    }

    window.idb = { get, set, del, queuePush, queueAll, queueDelete };
})();