index.js

import { refreshAllOfficialSources } from "./refresh";
import { getAllUnofficialSources } from "./unofficial";
import {errorResponse, rawResponse} from "./api";
import { Store } from "./store";
import { STORE_KEYS } from "./constants";
import {refreshTestingData} from "./refresh-icmr";

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
});

async function handleRequest(request) {
  const path = new URL(request.url).pathname.substr(ROUTE_PREFIX.length);
  const handler = getRouteHandler(path);
  return handler(request, path);
}

function getRouteHandler(path) {
  let handler = routeHandlers[path];
  if (!handler) {
    // get the handler with the longest matching prefix
    const routePrefixes = Object.keys(routeHandlers);
    let longestPrefix = "";
    for (let i=0; i<routePrefixes.length; i++) {
      if (path.startsWith(routePrefixes[i]) && longestPrefix.length < routePrefixes[i].length) {
        handler = routeHandlers[routePrefixes[i]];
        longestPrefix = routePrefixes[i];
      }
    }
  }
  return handler ? handler : notFoundHandler;
}

async function notFoundHandler() {
  return new Response('404 nothing to see here', { status: 404, statusText: 'Not Found' })
}

async function cachedData(request, key, decorator) {
  const isBrowser = (request.headers.get("accept") || "").toLowerCase().includes("html");
  try {
    const cacheGetStart = Date.now();
    let data = await Store.get(key);
    const cacheGetTimeTaken = Date.now() - cacheGetStart;
    if (decorator) data = decorator(data);
    if (isBrowser) data = JSON.stringify(typeof data === 'string' ? JSON.parse(data) : data, null, 2);
    const response = rawResponse(data);
    response.headers.append("Server-Timing", `cache;dur=${cacheGetTimeTaken}`);
    return response;
  } catch (err) {
    return errorResponse({ "message": err })
  }
}

async function fromBlobStore(originUrl) {
  // Fetch from origin server.
  let response = await fetch(originUrl);

  // Create an identity TransformStream (a.k.a. a pipe).
  // The readable side will become our new response body.
  let { readable, writable } = new TransformStream();

  // Start pumping the body. NOTE: No await!
  response.body.pipeTo(writable);

  // ... and deliver our Response while that's running.
  return new Response(readable, response)
}

function fixLocationNameChanges(content) {
  return content.replace(/Pondicherry/g, "Puducherry").replace(/Union Territory of /g, "");
}

async function getCovid19PatientDb(request, path) {
  path = path.replace(/^.+patientdb\/?/g, '');
  if (path === '') return cachedData(request, STORE_KEYS.CACHED_UNOFFICIAL_SRC_PREFIX + "covid19india.org");
  else if (path === 'history') return fromBlobStore('https://covid19-data.rootnet.in/covid19india.org/patientdb-historical.json');
  else {
    let response = await fetch(`https://covid19-data.rootnet.in/covid19india.org/patientdb-${path}.json`);
    if (response.status === 200) {
      let data = await response.json();
      return rawResponse(JSON.stringify({
        success: true,
        lastRefreshed: data.lastRefreshed,
        data,
      }))
    } else {
      return errorResponse({ message: response.statusText }, undefined, response.status);
    }
  }
}

const ROUTE_PREFIX = "/covid19-in";

const routeHandlers = {
  '/contacts': (request) => cachedData(request, STORE_KEYS.CACHED_CONTACTS),
  '/stats': (request) => cachedData(request, STORE_KEYS.CACHED_CASE_COUNTS),
  '/stats/latest': (request) => cachedData(request, STORE_KEYS.CACHED_CASE_COUNTS, fixLocationNameChanges),
  '/stats/daily': (request) => cachedData(request, STORE_KEYS.CACHED_CASE_COUNTS_HISTORY, fixLocationNameChanges),
  '/stats/history': (request) => cachedData(request, STORE_KEYS.CACHED_CASE_COUNTS_HISTORY, fixLocationNameChanges),
  '/stats/hospitals': (request) => cachedData(request, STORE_KEYS.CACHED_HOSPITAL_BEDS_COUNT),
  '/stats/testing/latest': (request) => cachedData(request, STORE_KEYS.CACHED_TESTING_HISTORY, data => {
    const j = JSON.parse(data);
    return {
      success: j.success,
      data: (j.data && j.data.length > 0) ? j.data[j.data.length-1] : {},
      lastRefreshed: j.lastRefreshed,
      lastOriginUpdate: j.lastOriginUpdate
    }
  }),
  '/stats/testing/history': (request) => cachedData(request, STORE_KEYS.CACHED_TESTING_HISTORY),
  '/stats/testing/raw': (request) => cachedData(request, STORE_KEYS.CACHED_TESTING_HISTORY_RAW),
  '/hospitals/beds': (request) => cachedData(request, STORE_KEYS.CACHED_HOSPITAL_BEDS_COUNT),
  '/hospitals/medical-colleges': (request) => cachedData(request, STORE_KEYS.CACHED_MEDICAL_COLLEGES),
  '/notifications': (request) => cachedData(request, STORE_KEYS.CACHED_NOTIFICATIONS),
  '/unofficial/sources': (request) => getAllUnofficialSources(request),
  '/unofficial/covid19india.org': (request) =>
      cachedData(request,STORE_KEYS.CACHED_UNOFFICIAL_SRC_PREFIX + "covid19india.org"),
  '/unofficial/covid19india.org/patientdb': (request) => getCovid19PatientDb(request),
  '/unofficial/covid19india.org/statewise': (request) =>
      cachedData(request,STORE_KEYS.CACHED_UNOFFICIAL_SRC_PREFIX + "covid19india.org_statewise"),
  '/unofficial/covid19india.org/statewise/history': (request) =>
      cachedData(request,STORE_KEYS.CACHED_UNOFFICIAL_SRC_PREFIX + "covid19india.org_statewise_history"),
  '/unofficial/covid19india.org/travelhistory': (request) =>
      cachedData(request,STORE_KEYS.CACHED_UNOFFICIAL_SRC_PREFIX + "covid19india.org_travelhistory"),
  '/refresh': (request) => refreshAllOfficialSources(request),
  '/refresh/testing': (request) => refreshTestingData(request)
};