IdexedDB Abstractation

import { openDB as openConnection, IDBPDatabase, DBSchema } from 'idb';

interface Schema extends DBSchema {
    'completed': {
        key: string;
        value: boolean;
    };
}

// type Names<Schema extends Object> =  keyof Schema;

class IndexedDB {
    private static _instance: IndexedDB | null = null;
    private _database!: IDBPDatabase<Schema>;

    private constructor() {}

    public static get instance(): IndexedDB {
        if (IndexedDB._instance === null) {
            IndexedDB._instance = new IndexedDB();
        }
        return IndexedDB._instance;
    }

    public async connect() {
        if(this._database === undefined) {
            this._database = await openConnection<Schema>('advancements_', 1, {
                upgrade(db: IDBPDatabase<Schema>) {
                    if (!db.objectStoreNames.contains('completed')) {
                        db.createObjectStore('completed', { keyPath: '_id' });
                    }
                }
            });
        }

        return this._database;
    }
}

export default IndexedDB;