/**
 * KeepItGoing - Offline IndexedDB helpers
 * Pure local storage access for offline task data. No network calls here —
 * see offline-sync.js for the /api/sync/ replay logic.
 */

const OFFLINE_DB_NAME = 'keepitgoing-offline';
const OFFLINE_DB_VERSION = 1;

function openOfflineDB() {
    return new Promise((resolve, reject) => {
        const request = indexedDB.open(OFFLINE_DB_NAME, OFFLINE_DB_VERSION);

        request.onupgradeneeded = (event) => {
            const db = event.target.result;
            if (!db.objectStoreNames.contains('tasks')) {
                db.createObjectStore('tasks', { keyPath: 'sync_id' });
            }
            if (!db.objectStoreNames.contains('meta')) {
                db.createObjectStore('meta', { keyPath: 'key' });
            }
        };

        request.onsuccess = () => resolve(request.result);
        request.onerror = () => reject(request.error);
    });
}

function promisifyRequest(request) {
    return new Promise((resolve, reject) => {
        request.onsuccess = () => resolve(request.result);
        request.onerror = () => reject(request.error);
    });
}

async function getMeta(key) {
    const db = await openOfflineDB();
    const tx = db.transaction('meta', 'readonly');
    const result = await promisifyRequest(tx.objectStore('meta').get(key));
    return result ? result.value : undefined;
}

async function setMeta(key, value) {
    const db = await openOfflineDB();
    const tx = db.transaction('meta', 'readwrite');
    await promisifyRequest(tx.objectStore('meta').put({ key, value }));
}

async function ensureDeviceId() {
    let deviceId = await getMeta('device_id');
    if (!deviceId) {
        deviceId = 'web-' + crypto.randomUUID();
        await setMeta('device_id', deviceId);
    }
    return deviceId;
}

async function getAllTasks() {
    const db = await openOfflineDB();
    const tx = db.transaction('tasks', 'readonly');
    return promisifyRequest(tx.objectStore('tasks').getAll());
}

async function putLocalTask(task) {
    const db = await openOfflineDB();
    const tx = db.transaction('tasks', 'readwrite');
    await promisifyRequest(tx.objectStore('tasks').put(task));
}

async function getDirtyTasks() {
    const tasks = await getAllTasks();
    return tasks.filter((t) => t._dirty === true);
}