calendar/packages/lib/timezone.ts

import type { ITimezoneOption } from "react-timezone-select";
import { allTimezones } from "react-timezone-select";

import type { ICity } from "@calcom/ui/components/form/timezone-select";

function findPartialMatch(itemsToSearch: string, searchString: string) {
  const searchItems = searchString.split(" ");
  return searchItems.every((i) => itemsToSearch.toLowerCase().indexOf(i.toLowerCase()) >= 0);
}

function findFromCity(searchString: string, data: ICity[]): ICity[] {
  if (searchString) {
    const cityLookup = data.filter((o) => findPartialMatch(o.city, searchString));
    return cityLookup?.length ? cityLookup : [];
  }
  return [];
}

export const filterByCities = (tz: string, data: ICity[]): ICity[] => {
  const cityLookup = findFromCity(tz, data);
  return cityLookup.map(({ city, timezone }) => ({ city, timezone }));
};

export const addCitiesToDropdown = (cities: ICity[]) => {
  const cityTimezones = cities?.reduce((acc: { [key: string]: string }, city: ICity) => {
    if (Object.keys(allTimezones).includes(city.timezone)) {
      acc[city.timezone] = city.city;
    }
    return acc;
  }, {});
  return cityTimezones || {};
};

export const handleOptionLabel = (option: ITimezoneOption, cities: ICity[]) => {
  const timezoneValue = option.label.split(")")[0].replace("(", " ").replace("T", "T ");
  const cityName = option.label.split(") ")[1];
  return cities.length > 0 ? `${cityName}${timezoneValue}` : `${option.value}${timezoneValue}`;
};