"use strict";

const url = require("url");
const ValidationError = require("@validatem/error");

module.exports = function (protocols) {
	if (protocols != null && !Array.isArray(protocols)) {
		throw new Error(`Permitted protocol list must be an array`);
	}

	let protocolSet = (protocols != null)
		? new Set(protocols.map((protocol) => protocol.toLowerCase()))
		: null;

	return function isURL(value) {
		let parsed = url.parse(value);

		let parsedProtocol = (parsed.protocol != null)
			? parsed.protocol.replace(/:$/, "")
			: null;

		if (parsedProtocol == null) {
			return new ValidationError("Must be a valid URL");
		} else if (protocolSet != null && !protocolSet.has(parsedProtocol.toLowerCase())) {
			let validProtocolList = protocols
				.map((protocol) => protocol.toUpperCase())
				.join(", ");

			return new ValidationError(`Must be a URL with one of the following protocols: ${validProtocolList} - but got ${parsedProtocol.toUpperCase()} instead`);
		} else {
			return parsed;
		}
	}
};