import { MongoClient, Db } from 'mongodb';
import _, { difference } from 'lodash';
import { differenceBetweenObject } from '@seed/helpers/Utils';

export const createSetRequest = <T>(field: string, data: object, oldObject?: any): Partial<T> => {
    let dataToChange;
    if (oldObject) dataToChange = differenceBetweenObject(data, oldObject);
    else dataToChange = data;

    const req: any = {};
    for (const key in dataToChange) {
        if (dataToChange.hasOwnProperty(key)) {
            if (_.isPlainObject(dataToChange[key])) {
                if (field != '') req[`${field}.${key}`] = createSetRequest(key, dataToChange[key]);
                else req[`${key}`] = createSetRequest('', dataToChange[key]);
            } else {
                if (field != '') req[`${field}.${key}`] = dataToChange[key];
                else req[`${key}`] = dataToChange[key];
            }
        }
    }

    return req;
};

export default class DB {
    private static instance: DB;
    public mongoClient!: MongoClient;
    public db!: Db;

    // eslint-disable-next-line @typescript-eslint/no-empty-function
    private constructor() {}

    public static async getInstance(): Promise<DB> {
        if (!this.instance || !this.instance.mongoClient || !this.instance.mongoClient.isConnected) {
            this.instance = new DB();

            let mongoUrl;
            if (process.env.MONGO_USER && process.env.MONGO_PWD)
                mongoUrl = `mongodb+srv://${process.env.MONGO_USER}:${process.env.MONGO_PWD}@${process.env.MONGO_URL}`;
            else mongoUrl = process.env.MONGO_URL || '';
            const mongoDb = process.env.MONGO_DB || '';

            try {
                this.instance.mongoClient = await MongoClient.connect(mongoUrl, {
                    useNewUrlParser: true,
                    useUnifiedTopology: true,
                    // loggerLevel: 'debug',
                });
                this.instance.db = this.instance.mongoClient.db(mongoDb);
                if (process.env.NODE_ENV != 'production') console.log('[MongoDB] New Connect');
            } catch (error) {
                throw error;
            }
        } else {
            if (process.env.NODE_ENV != 'production') console.log('[MongoDB] Existing Connect');
        }

        return DB.instance;
    }
}