Get Fife bin calendar

fife.ts

import PQueue from "p-queue";
import fetch, { Request, RequestInit, Response } from "node-fetch";
import { z } from "zod";
import { Temporal } from "@js-temporal/polyfill";

class HTTPError extends Error {}

// be nice to the council: one request per second, never more than one at a time
const queue = new PQueue({ concurrency: 1, interval: 5000, intervalCap: 5 });

type Session = {
  fetch: (path: string, opts: RequestInit | undefined) => Promise<Response>;
};

export const makeSession = async (): Promise<Session> => {
  let token: string | null;

  const fetchWithToken = async (path: string, opts: RequestInit = {}) => {
    console.log("making council request: " + path);
    const req = new Request("https://www.fife.gov.uk/api/" + path, opts);
    if (token) req.headers.set("authorization", token);
    req.headers.set("user-agent", "Bins/1.0 (gbs@canishe.com)");
    const res = await queue.add(async () => await fetch(req), {
      throwOnTimeout: true,
    });
    token = res.headers.get("authorization");
    if (!res.ok) {
      throw new HTTPError("HTTP " + res.statusText);
    }
    return res;
  };

  await fetchWithToken("citizen?preview=false&locale=en");

  return { fetch: fetchWithToken };
};

const addressesSchema = z.object({
  data: z.array(z.object({ value: z.string(), label: z.string() })),
});

const propertySchema = z.object({
  profileData: z.object({
    "property-UPRN": z.string(),
    "property-Address": z.string(),
  }),
});

const calendarSchema = z.object({
  data: z.union([
    z.object({ results_returned: z.literal("false") }),
    z.object({
      results_returned: z.literal("true"),
      tab_collections: z.array(
        z.object({ colour: z.string(), date: z.string(), type: z.string() })
      ),
    }),
  ]),
});

export async function getAddressesAtPostcode(
  session: Session,
  postcode: string
) {
  const res = await session.fetch(
    "widget?action=propertysearch&actionedby=ps_3SHSN93&loadform=true&access=citizen&locale=en",
    {
      body: JSON.stringify({
        caseid: "",
        data: { postcode },
        email: "",
        name: "bin_calendar",
        xref: "",
        xref1: "",
        xref2: "",
      }),
      method: "post",
      headers: { "content-type": "application/json" },
    }
  );

  const data = addressesSchema.parse(await res.json());

  return data.data.map(({ value, label }) => ({ address: label, id: value }));
}

export async function getProperty(session: Session, addressId: string) {
  const res = await session.fetch(
    `getobjectdata?objecttype=property&objectid=${addressId}`,
    { method: "post" }
  );

  const json = propertySchema.parse(await res.json());

  return {
    address: json.profileData["property-Address"],
    uprn: json.profileData["property-UPRN"],
  };
}

export async function getBinCalendar(session: Session, uprn: string) {
  const res = await session.fetch(
    "custom?action=powersuite_bin_calendar_collections&actionedby=bin_calendar&loadform=true&access=citizen&locale=en",
    {
      method: "post",
      headers: { "content-type": "application/json" },
      body: JSON.stringify({
        name: "bin_calendar",
        data: { uprn },
        email: "",
        caseid: "",
        xref: "",
        xref1: "",
        xref2: "",
      }),
    }
  );

  const calendar = calendarSchema.parse(await res.json());

  if (calendar.data.results_returned == "false") {
    return null;
  } else {
    return calendar.data.tab_collections.map((collection) => {
      const [_weekDay, month, day, year] = collection.date
        .split(" ")
        .map((x) => x.replace(",", ""));
      const months = [
        "January",
        "February",
        "March",
        "April",
        "May",
        "June",
        "July",
        "August",
        "September",
        "October",
        "November",
        "December",
      ];
      return {
        description: collection.type,
        date: new Temporal.PlainDate(
          parseInt(year),
          months.indexOf(month) + 1,
          parseInt(day)
        ),
      };
    });
  }
}