hk-bus-eta-skpracta/src/lrtfeeder.ts

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

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

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

export default function fetchEtas({
  stopId,
  route,
  language,
}: fetchEtasProps): Promise<Eta[]> {
  return fetch(`https://rt.data.gov.hk/v1/transport/mtr/bus/getSchedule`, {
    method: "POST",
    cache: isSafari ? "default" : "no-store",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      language: language,
      routeName: route,
    }),
  })
    .then((response) => response.json())
    .then(({ busStop }) =>
      busStop
        .filter(({ busStopId }: any) => busStopId === stopId)
        .reduce(
          (ret: any, { bus: buses }: any) => [
            ...ret,
            ...buses.reduce((etas: Eta[], bus: any) => {
              // hackily use +8 hours and use UTC hour to resolve timezone issue
              const etaDate = new Date(
                Date.now() +
                  parseInt(
                    bus.arrivalTimeInSecond === "108000"
                      ? bus.departureTimeInSecond
                      : bus.arrivalTimeInSecond,
                    10,
                  ) *
                    1000 +
                  8 * 3600000,
              );

              return [
                ...etas,
                {
                  eta:
                    `${etaDate.getUTCFullYear()}-${`0${
                      etaDate.getUTCMonth() + 1
                    }`.slice(-2)}-${`0${etaDate.getUTCDate()}`.slice(-2)}` +
                    `T${`0${etaDate.getUTCHours()}`.slice(
                      -2,
                    )}:${`0${etaDate.getMinutes()}`.slice(
                      -2,
                    )}:${`0${etaDate.getSeconds()}`.slice(-2)}+08:00`,
                  remark: {
                    [language]:
                      bus.busRemark ||
                      (bus.isScheduled === "1"
                        ? language === "en"
                          ? "Scheduled"
                          : "預定班次"
                        : ""),
                  },
                  dest: {
                    zh: "",
                    en: "",
                  },
                  co: "lrtfeeder",
                },
              ];
            }, []),
          ],
          [],
        ),
    );
}