import { invariant } from "./utils.js";
export function UnicodeExtensionComponents(extension) {
	invariant(extension === extension.toLowerCase(), "Expected extension to be lowercase");
	invariant(extension.slice(0, 3) === "-u-", "Expected extension to be a Unicode locale extension");
	const attributes = [];
	const keywords = [];
	let keyword;
	let size = extension.length;
	let k = 3;
	while (k < size) {
		let e = extension.indexOf("-", k);
		let len;
		if (e === -1) {
			len = size - k;
		} else {
			len = e - k;
		}
		let subtag = extension.slice(k, k + len);
		invariant(len >= 2, "Expected a subtag to have at least 2 characters");
		if (keyword === undefined && len != 2) {
			if (attributes.indexOf(subtag) === -1) {
				attributes.push(subtag);
			}
		} else if (len === 2) {
			keyword = {
				key: subtag,
				value: ""
			};
			if (keywords.find((k) => k.key === keyword?.key) === undefined) {
				keywords.push(keyword);
			}
		} else if (keyword?.value === "") {
			keyword.value = subtag;
		} else {
			invariant(keyword !== undefined, "Expected keyword to be defined");
			keyword.value += "-" + subtag;
		}
		k += len + 1;
	}
	return {
		attributes,
		keywords
	};
}