utils.js

const Papa = require('papaparse');
const {format, parse, formatDate} = require('date-fns');
const { formatInTimeZone } = require('date-fns-tz');
const { SYMBOLS, OLD_SYMBOLS, LISTED_COMPANIES, PNGX_DATA_URL, PNGX_URL, LOCAL_TIMEZONE, LOCAL_TIMEZONE_FORMAT } = require("./constants");

function date_split(date) {
	const [month, day, year] = date.split('/');
	const result = [year, month, day].join('-');

	return result;
}

/**
 * This function takes in date of any format and spits out the desired format `yyyy/MM/dd` used here
 * @param {*} date 
 * @returns Date
 */
function format_date(date) {
	// only for STO's date i.e. 30/09/2024 - dd/MM/yyyy
	if (date.match(new RegExp('^((0[1-9]|[12][0-9]|3[01])/(01|03|05|07|08|10|12)/([0-9]{4}))|((0[1-9]|[12][0-9]|30)/(04|06|09|11)/([0-9]{4}))|((0[1-9]|1[0-9]|2[0-8])/02/([0-9]{4}))|(29/02/([0-9]{2}(0[48]|[2468][048]|[13579][26])|([048][048]|[13579][26])00))$'))) {
		let parseDate = parse(date, "dd/MM/yyyy", new Date())
		// fixing timezone issues on clever-cloud.io
		let localTime = formatInTimeZone(parseDate, LOCAL_TIMEZONE, LOCAL_TIMEZONE_FORMAT)
		return new Date(localTime);
	}
	// rest of the quotes 2019/11/18 - yyyy/MM/dd
	// else if (date.match(/\d{2,4}-\d{1,2}-\d{1,2}/)) {

	// }
	else {
		return new Date(date);
	}
}

function normalize_data(data) {
	let quote = {};
	let formattedDate = format_date(data['Date'])

	quote['date'] = formattedDate;
	quote['code'] = data['Short Name'];
	quote['short_name'] = data['Short Name'];
	quote['bid'] = Number(data['Bid']);
	quote['offer'] = Number(data['Offer']);
	quote['last'] = Number(data['Last']);
	quote['close'] = Number(data['Close']);
	quote['high'] = Number(data['High']);
	quote['low'] = Number(data['Low']);
	quote['open'] = Number(data['Open']);
	quote['chg_today'] = Number(data['Chg. Today']);
	quote['vol_today'] = Number(data['Vol. Today']);
	quote['num_trades'] = Number(data['Num. Trades']);

	return quote;
}


async function parallel(arr, fn, threads = 2) {
	const result = [];

	while (arr.length) {
		const res = await Promise.all(arr.splice(0, threads).map(x => fn(x)));
		result.push(res);
	}
	return result.flat();
}


/**
 * Parses CSV format to JSON format for easy manipulation of data
 */
function parse_csv_to_json2(body) {
	console.log("parsing csv to json");
	var i = [];
	// split the data into array by whitespaces
	// var o = body.split(/\r\n|\n/);

	// split the first row of that array only by comma (,) to get headers
	// var a = o[0].split(",");

	// loop through the other rows to obtain data
	for (var o = body.split(/\r\n|\n/), a = o[0].split(","), s = 1; s < o.length; s++) {
		// split each row by comma
		var l = o[s].split(",")
		// compare the splited row with the first/header row
		if (l.length == a.length) {
			// run through the header row
			// attaches splited row to the header row
			// then store it on variable d
			// create array by pushing the stored data to the variable i
			for(var d = {}, u = 0; u < a.length; u++) d[a[u]] = l[u]; i.push(d)
		}
	}
	// i[i.length -1]
	return i;
}

function parse_csv_to_json(csv) {
	let {errors, data, meta} = Papa.parse(csv, {
		header: true,
		dynamicTyping: true,
		skipEmptyLines: true
	});

	if (errors.length > 0) throw new Error(errors);

	return data;

	// Parse local CSV file
	// Stream big file in worker thread
	// Papa.parse(bigFile, {
	// 	worker: true,
	// 	step: function(results) {
	// 		console.log("Row:", results.data);
	// 	},
	// 	complete: function(results) {
	// 		console.log("Finished:", results.data);
	// 	}
	// });
}

function createWorker() {
	return new Promise(function (resolve, reject) {
		const worker = new Worker("./thread_workers.js", {
			workerData: { thread_count: THREAD_COUNT },
		});
		worker.on("message", (data) => {
			resolve(data);
		});
		worker.on("error", (msg) => {
			reject(`An error ocurred: ${msg}`);
		});
	});
}  

module.exports = {
	parse_csv_to_json,
	parallel,
	normalize_data,
	format_date,
	date_split
}