index.ts

import {generateUniqueId} from './helpers/util';
import Database from './helpers/db';
import mongoose,{Connection} from 'mongoose'

export default class MaskUrl {
  dbString: string;
  urlPrefix: string;
  connection!: Connection | Error;
  database!: Database;
  UrlModel!: typeof mongoose.Model   ;

  constructor(dbString: string, urlPrefix: string) {
    this.dbString = dbString;
    this.urlPrefix = urlPrefix;
  }
  async connectToDatabase(): Promise<void> {
    try {
      this.database = new Database(this.dbString);
      this.connection = await this.database.connect();
      const connection = this.connection as mongoose.Connection;

      this.UrlModel = connection.model('Url', new mongoose.Schema({
        id: String,
        prefix: String,
        url: String,
    }));        

    } catch (error) {
        throw error;
    }
  }

  maskUrl(url: string): string {
    if (this.connection) {
        const uniqueId = generateUniqueId();
        const redirectionUrl = `${this.urlPrefix.trim()}/${uniqueId}`;
        const newUrl = new this.UrlModel({
            id: uniqueId,
            prefix: this.urlPrefix,
            url: url,
        });
        newUrl.save();
      return redirectionUrl;
    } else {
      throw new Error('Database connection is not established');
    }
  }

  async fetchUrl(_url:string){
    if (this.connection) {
        const id = _url.split("/").pop();
        try {
            const urlDocument = await this.UrlModel.findOne({ id });
            if (urlDocument) {
                // Return the URL if found
                return urlDocument.url;
            } else {
                // Return null if no URL found with the provided ID
                return null;
            }
        } catch (error) {
            // Handle any errors that occur during the database operation
            throw new Error('Error fetching URL from database.');
        }
    }else{
        throw new Error('Database connection is not established');
    }
  }
}

module.exports = MaskUrl;