require-either/index.js

"use strict";

const flatten = require("flatten");
const assureArray = require("assure-array");

const required = require("@validatem/required");
const forbidden = require("@validatem/forbidden");
const allowExtraProperties = require("@validatem/allow-extra-properties");
const either = require("@validatem/either");

module.exports = function requireEither(alternatives, options = {}) {
	let allKeys = flatten(alternatives);
	let allUniqueKeys = Array.from(new Set(allKeys));
	
	let predicates = alternatives.map((alternative) => {
		let requiredKeys = assureArray(alternative);
		let requiredKeysSet = new Set(requiredKeys);

		let object = {};

		for (let key of requiredKeys) {
			object[key] = required;
		}

		if (!options.allowMultiple) {
			for (let key of allUniqueKeys) {
				if (!requiredKeysSet.has(key)) {
					object[key] = forbidden;
				}
			}
		}

		return allowExtraProperties(object);
	});

	return either(predicates);
};