'use strict';
const execa = require('execa');

const macos = () => execa.stdout('netstat', ['-anv', '-p', 'tcp'])
	.then(data => Promise.all([data, execa.stdout('netstat', ['-anv', '-p', 'udp'])]))
	.then(data => data.join('\n'));

const linux = () => execa.stdout('ss', ['-tunlp']);
const win32 = () => execa.stdout('netstat', ['-ano']);

const getListFn = process.platform === 'darwin' ? macos : process.platform === 'linux' ? linux : win32;
const cols = process.platform === 'darwin' ? [3, 8] : process.platform === 'linux' ? [4, 6] : [1, 4];
const isProtocol = x => /^\s*(tcp|udp)/i.test(x);

const parsePid = input => {
	if (typeof input !== 'string') {
		return null;
	}

	const match = input.match(/(?:^|",|",pid=)(\d+)/);
	return match ? parseInt(match[1], 10) : null;
};

const getPort = (input, list) => {
	const regex = new RegExp(`[.:]${input}$`);
	const port = list.find(x => regex.test(x[cols[0]]));

	if (!port) {
		throw new Error(`Couldn't find a process with port \`${input}\``);
	}

	return parsePid(port[cols[1]]);
};

const getList = () => getListFn().then(list => list
	.split('\n')
	.reduce((result, x) => {
		if (isProtocol(x)) {
			result.push(x.match(/\S+/g) || []);
		}

		return result;
	}, [])
);

module.exports = input => {
	if (typeof input !== 'number') {
		return Promise.reject(new TypeError(`Expected a number, got ${typeof input}`));
	}

	return getList().then(list => getPort(input, list));
};

module.exports.all = input => {
	if (!Array.isArray(input)) {
		return Promise.reject(new TypeError(`Expected an array, got ${typeof input}`));
	}

	return getList()
		.then(list => Promise.all(input.map(x => [x, getPort(x, list)])))
		.then(list => new Map(list));
};

module.exports.list = () => getList().then(list => {
	const ret = new Map();

	for (const x of list) {
		const match = x[cols[0]].match(/[^]*[.:](\d+)$/);

		if (match) {
			ret.set(parseInt(match[1], 10), parsePid(x[cols[1]]));
		}
	}

	return ret;
});