BarevClub/packages/core/src/deeplink.ts

import { isLocale, type Locale } from './types.ts';

/**
 * Payload для t.me/<bot>?start=<payload> (LND-3, ONB-1).
 * Telegram ограничивает его 64 символами из [A-Za-z0-9_-], поэтому формат компактный:
 *
 *   l-ru_a-AGENCY1      язык и код агентства
 *   s-k3j9x2            короткий токен; язык, агентство и UTM лежат в БД (StartToken)
 *
 * Части разделены "_", ключ и значение — "-". Неизвестные части игнорируются.
 */
export interface StartPayload {
  locale?: Locale;
  agency?: string;
  token?: string;
}

export const START_PAYLOAD_MAX = 64;
const SAFE = /^[A-Za-z0-9]+$/;

export function normalizeAgencyCode(code: string): string | null {
  const c = code.trim().toUpperCase();
  return SAFE.test(c) && c.length <= 32 ? c : null;
}

export function encodeStartPayload(p: StartPayload): string {
  const parts: string[] = [];
  if (p.token) {
    if (!SAFE.test(p.token)) throw new Error('Bad token');
    parts.push(`s-${p.token}`);
  }
  if (p.locale) parts.push(`l-${p.locale}`);
  if (p.agency) {
    const a = normalizeAgencyCode(p.agency);
    if (a) parts.push(`a-${a}`);
  }
  const out = parts.join('_');
  if (out.length > START_PAYLOAD_MAX) throw new Error('Start payload too long');
  return out;
}

export function decodeStartPayload(raw: string | undefined | null): StartPayload {
  const out: StartPayload = {};
  if (!raw) return out;
  for (const part of raw.slice(0, START_PAYLOAD_MAX).split('_')) {
    const [key, value] = [part.slice(0, 1), part.slice(2)];
    if (part[1] !== '-' || !value) continue;
    if (key === 'l' && isLocale(value)) out.locale = value;
    else if (key === 'a') {
      const a = normalizeAgencyCode(value);
      if (a) out.agency = a;
    } else if (key === 's' && SAFE.test(value)) out.token = value;
  }
  return out;
}

export const UTM_KEYS = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_content', 'utm_term'] as const;
export type Utm = Partial<Record<(typeof UTM_KEYS)[number], string>>;

export function pickUtm(params: URLSearchParams): Utm {
  const utm: Utm = {};
  for (const k of UTM_KEYS) {
    const v = params.get(k);
    if (v) utm[k] = v.slice(0, 120);
  }
  return utm;
}

export function botLink(username: string, payload: string): string {
  return `https://t.me/${username}${payload ? `?start=${payload}` : ''}`;
}