"use strict";

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

module.exports = function extendClassnames(classes, mapper) {
	return assureArray(classes).map((item) => {
		if (typeof item === "string") {
			return mapper(item);
		} else if (Array.isArray(item)) {
			return item.map((subItem) => {
				return mapper(subItem);
			});
		} else {
			// { className: condition } mapping
			return syncpipe(item, [
				(_) => Object.entries(_),
				(_) => _.map(([ key, value ]) => syncpipe(key, [
					(_) => mapper(_),
					(_) => assureArray(_),
					(_) => _.filter((className) => className != null),
					(_) => _.map((className) => [ className, value ])
				])),
				(_) => flatten(_, 1),
				(_) => Object.fromEntries(_),
			]);
		}
	});
};