const db = require("../db.js");
var CryptoJS = require('crypto-js');

class UserRepository {
	login(params){
		const {
			username,
			password
		} = params;
		return db.get('user:' + username).
		then((data) => {
			if (data.password === CryptoJS.SHA256(data.salt + password).toString()) {
				// match 
				// generate token
  				let Token = CryptoJS.SHA256(Math.random().toString() + data.salt).toString();
  				data.token = Token;
  				return db.put('user:' + username, data).then(() => data);
			}
			let error = new Error("Bad Credentials");
			error.name = "BadCredentials";
			throw error;
		});
	}
	register(params) {
		const {
			username,
			password,
			email
		} = params;

    	const hashFn = CryptoJS.SHA256;
    	const salt = CryptoJS.lib.WordArray.random(128 / 8).toString();
    	const hash = hashFn(salt + password).toString();
    	const newuser = { 
			email,
			password: hash,
			salt: salt,
			username
		};
    	//check if username exists 
    	return db.get('user:' + username).
    	then((data) => {
    		let error = new Error("Username exists: " + username);
    		error.name = "UsernameExists";
    		throw error;
    	}).
    	catch((err) => {
    		if( err.name === "NotFoundError" ) {
    			//register 
    			return db.put('user:' + username, newuser);
    		}
    		throw err;
    	}).
    	then(() => newuser);
	}
	getUser(token) {
		return new Promise((res,rej) => {
			db.search(['token', token]).
			on('data', (data) => {
				res(data);
			}).
			on('error', function (err) {
				let error = new Error("DB error");
				error.name = "InternalError";
				rej(error);
		  	}).
		  	on('close', function () {
		    	let error = new Error("Token invalid");
				error.name = "TokenInvalid";
				rej(error);
		  	}).
		  	on('end', function () {
				let error = new Error("Token invalid");
				error.name = "TokenInvalid";
				rej(error);
			});
		});
	}
	getByID(id){
		return db.get("user:" + id);
	}
}
let userRepository = null;
function getSingleton() { 
	return userRepository = ( userRepository === null ? new UserRepository(): userRepository);
}
module.exports = getSingleton();