/* eslint max-statements-per-line: ["error", { "max": 2 }] */
const suffixes = /(#|\/)+$/;
const trailingHash = /#$/;
const isDomain = /^[^:]+:\/\/[^/]+\//;
const trailingFragments = /\/[^/]*$/;
const idAndPointer = /#.*$/;


export default function joinScope(previous?: string, id?: string) {
    if (previous == null && id == null) { return "#"; }
    if (id == null) { return previous.replace(trailingHash, ""); }
    if (previous == null) { return id.replace(trailingHash, ""); }
    if (id[0] === "#") { return `${previous.replace(idAndPointer, "")}${id.replace(suffixes, "")}`; }
    if (isDomain.test(id)) { return id.replace(trailingHash, ""); }
    return `${previous.replace(trailingFragments, "")}/${id.replace(trailingHash, "")}`;
}