util.ts

import type { TFunction } from 'i18next';

export type QueryStringArray = Array<[string, string | null]>;

function unsafeDecode(str: string): string {
  return decodeURIComponent(str);
}

export function parseQueryString(searchOrHash: string): QueryStringArray {
  const first = searchOrHash.slice(0, 1);
  const qs = first === '#' || first === '?' ? searchOrHash.slice(1) : searchOrHash;
  const parts = qs.split('&').filter((x) => x !== '');

  const decode = (s: string) => unsafeDecode(s.replace(/\+/g, ' '));

  const out: QueryStringArray = [];
  for (const kv of parts) {
    const [k, ...rest] = kv.split('=');
    if (!k) continue;
    if (rest.length === 0) out.push([decode(k), null]);
    else if (rest.length === 1) out.push([decode(k), decode(rest[0] ?? '')]);
  }
  return out;
}

export function curQuerystring(): QueryStringArray {
  return parseQueryString(window.location.search);
}

export function lookupQueryStringValue(qs: QueryStringArray, k: string): string | null {
  for (const [key, val] of qs) {
    if (key === k) return val;
  }
  return null;
}

export function encodeTag(tag: string): string {
  return encodeURIComponent(tag.replace(/\+/g, '%2B'));
}

export function fromNullableStr(s: string | null | undefined): string {
  return s ?? '';
}

export function normalizeTags(tags: string | null): string {
  return tags?.replace(/,/g, ' ').replace(/\s+/g, ' ').trim() ?? '';
}

export function apiErrorMsg(t: TFunction, status: number, bodyText: string): string {
  const body = bodyText.trim();
  if (!body.includes('\n') && !body.includes('doctype html') && body.length > 0) {
    return t('error.errorWithMsg', { status, msg: body });
  }
  return t('error.error', { status });
}

/**
 * Generates a short, non-cryptographic hash from a string.
 * @param str - The input string to hash.
 * @returns A short alphanumeric string hash.
 */
export function getShortHash(str: string): string {
  let hash = 5381;
  let i = str.length;

  while (i) {
    hash = (hash * 33) ^ str.charCodeAt(--i);
  }

  // Convert to an unsigned 32-bit integer, then to a base36 string
  return (hash >>> 0).toString(36);
}