hk-bus-eta/src/nlb.ts

Query the ETA (Estimated Time of Arrival) of HK Bus/Minibus/MTR/Lightrail

import type { Eta, RouteListEntry } from "./type";
import { isSafari } from "./utils";

interface fetchEtasProps {
  stopId: string;
  nlbId: RouteListEntry["nlbId"];
  language: "zh" | "en";
}

export default function fetchEtas({
  stopId,
  nlbId,
  language,
}: fetchEtasProps): Promise<Eta[]> {
  return fetch(
    `https://rt.data.gov.hk/v2/transport/nlb/stop.php?action=estimatedArrivals&routeId=${nlbId}&stopId=${stopId}&language=${language}`,
    {
      cache: isSafari ? "default" : "no-store",
    },
  )
    .then((response) => response.json())
    .then(({ estimatedArrivals, message }) => {
      const outputs = (estimatedArrivals ?? [])
        .filter((eta: any) => eta.estimatedArrivalTime)
        .map((e: any) => {
          const isScheduled = e.departed !== "1" || e.noGPS === "1";
          return {
            eta: e.estimatedArrivalTime.replace(" ", "T") + ".000+08:00",
            remark: {
              zh: isScheduled ? "預定班次" : "",
              en: isScheduled ? "Scheduled" : "",
            },
            dest: {
              // e.g. 經: 梅窩舊墟
              // e.g. Via: Mui Wo Old Town
              zh: language === "zh" ? e.routeVariantName : "",
              en: language === "en" ? e.routeVariantName : "",
            },
            co: "nlb",
          };
        });

      if (outputs.length === 0) {
        if (message && typeof message === "string") {
          return [
            {
              eta: "",
              remark: {
                zh: language === "zh" ? message : "",
                en: language === "en" ? message : "",
              },
              dest: {
                zh: "",
                en: "",
              },
              co: "nlb",
            },
          ];
        }
      }

      return outputs;
    });
}