watch.js

require("dotenv").config();
const accountSid = process.env.TWILIO_ACCOUNT_SID;
const authToken = process.env.TWILIO_AUTH_TOKEN;

const notifyPhoneNumber = process.env.NOTIFY_PHONE_NUMBER;
const twilioPhoneNumber = process.env.TWILIO_PHONE_NUMBER;

const client = require("twilio")(accountSid, authToken);

const fs = require("fs");
var contents = JSON.parse(fs.readFileSync("./config.json"));
const checkEveryXSeconds = contents.CheckEveryXSeconds;
const statusFileName = contents.StatusFileName;
const debugFileName = contents.DebugFileName;
const endDate = contents.EndDate;
const startDate = contents.StartDate;

console.log(statusFileName);
let pctPermitAvailabilityWebsite = "https://portal.permit.pcta.org/availability/mexican-border.php";

let messagesSent = [];

console.log("watching pct availability page on a constant loop every " + checkEveryXSeconds + " seconds");

const WriteStatus = (message) => {
  fs.writeFile(statusFileName, message, (err) => {
    if (err) throw err;
  });
};

const WriteDebugLog = (log) => {
  fs.writeFile(debugFileName, `${new Date()}:${log}\n`, { flag: "a" }, (err) => {
    if (err) throw err;
  });
};

const WriteLatestStatus = (date, responseCode, hasCalendar) => {
  WriteStatus(`Latest Time Checked: ${date}\nLatest Response Code: ${responseCode}\nHas Calendar: ${hasCalendar}\n`);
};
const StringifyAvailablePermits = (availablePermits) => {
  let message = "";

  availablePermits.map((permit) => {
    message += `(${permit.start_date}:${35 - permit.num}) `;
  });

  return message;
};

const GetNonSentMessages = (availablePermits) =>
  availablePermits.filter((permit) => messagesSent.find((sentPermit) => sentPermit.start_date == permit.start_date) == undefined);

const CheckForPermitsAvailable = async (websiteSource, beginning_date) => {
  let permitInfo = await JSON.parse(websiteSource.match(/(?<=data\s=\s){.*}/gm));
  let availablePermits = [];
  let datesChecked = 0;

  console.log("checking permit info at " + new Date());
  //console.log(permitInfo.calendar);
  if (permitInfo == null) {
    console.error("ruh roh, permit info is null");
    console.error("here is the website source");
    console.error(websiteSource);
  } else {
    permitInfo.calendar.map((date) => {
      if (date.start_date >= startDate && date.start_date <= endDate) {
        // only check dates in march/april/may
        datesChecked++;
        if (date.num != 50) {
          console.log("we found " + (50 - date.num) + " permit(s) on " + date.start_date);
          availablePermits = [...availablePermits, date];
        }
      }
    });

    WriteLatestStatus(new Date(), 200, datesChecked != 0);

    if (availablePermits.length > 0) {
      let nonSentMessages = GetNonSentMessages(availablePermits);

      if (nonSentMessages.length > 0) {
        console.log(`Open Permits ${StringifyAvailablePermits(availablePermits)}`);

        console.log(`Sending message to ${notifyPhoneNumber} from ${twilioPhoneNumber}`);

        let body = "Open Permits " + StringifyAvailablePermits(nonSentMessages);
        client.messages.create({
          body: body,
          from: twilioPhoneNumber,
          to: notifyPhoneNumber,
        });

        WriteDebugLog(`Sent message to ${notifyPhoneNumber} from ${twilioPhoneNumber} with body ${body}`);

        messagesSent = [...messagesSent, ...nonSentMessages];
      } else {
        WriteDebugLog("Permits were available but they have all been sent");
      }
    } else {
      WriteDebugLog("We did not find any available permits at " + new Date());
    }
  }
};

const CheckWebsite = () => {
  try {
    fetch(pctPermitAvailabilityWebsite)
      .then((website) => website.text())
      .then((text) => CheckForPermitsAvailable(text));
  } catch (ex) {
    console.error("failed to fetch at " + new Date());
  }
};

setInterval(CheckWebsite, checkEveryXSeconds * 1000);