red.cl API wrapper

A wrapper for Transantiago API to get bus arrival predictions.

Motivation

At the time of writing, the only public API for transantiago (scltrans.it) has a critical endpoint that is not working (next_arrivals).

For example, https://api.scltrans.it/v2/stops/PA10/next_arrivals returns a {"title": "smsbus webservice timeout"}.

This project implements next_arrivals using a wrapper over red.cl service.

How to use

`GET https://red-api.chewy.workers.dev/stops/:stopId/next_arrivals`

Returns information on upcoming arrivals at the given bus stop. The response format mimics scltrans's implementation.

Example: To make a prediction for PA10 bus stop, use https://red-api.chewy.workers.dev/stops/PA10/next_arrivals

Example response:

{
  "results": [
    {
      "bus_distance": "479",
      "arrival_estimation": "Llegando.",
      "bus_plate_number": "CJRY-88",
      "route_id": "119",
      "code": "00",
      "message": "",
      "calculated_at": "2021-10-25 11:24",
      "is_live": true
    },
    {
      "bus_distance": "2633",
      "arrival_estimation": "Entre 06 Y 08 min. ",
      "bus_plate_number": "BJFV-75",
      "route_id": "119",
      "code": "00",
      "message": "",
      "calculated_at": "2021-10-25 11:24",
      "is_live": true
    },
    {
      "bus_distance": "2871",
      "arrival_estimation": "Entre 09 Y 13 min. ",
      "bus_plate_number": "CJRX-36",
      "route_id": "345",
      "code": "00",
      "message": "",
      "calculated_at": "2021-10-25 11:24",
      "is_live": true
    }
  ]
}

How it works

The webpage https://www.red.cl/planifica-tu-viaje/cuando-llega/ gets predictions form https://www.red.cl/predictor/prediccion. This endpoint works with 3 query params:

t: authentication token
codsimt: bus stop ID
codser: bus ID

If you check the source page, you'll notice that t param is a string present in a script tag. Example:

$jwt =
  'ZXlKMGVYQWlPaUpLVjFRaUxDSmhiR2NpT2lKSVV6STFOaUo5LmV5SmxlSEFpT2pFMk16VXhOekV6TWpBMU1UQjkuNlJRVkZ3RUgzNm1zMUJFdWw5Q2I3QlhlN21YRkR3eG1RN1hBVzl4SUx1VQ=='
$codsimt = 'PA1'
$codsimt = $codsimt.toUpperCase()
var rutaTheme = 'https://www.red.cl/wp-content/themes/red'
consultaParadero($jwt, $codsimt, desvios)

Although it is not used right away. consultaParadero decodes it at the beginning of the function:

$jwt_decoded = atob($jwt)

All that said, the next_arrivals endpoint was implemented like this:

Step 1: Get the token from https://www.red.cl/planifica-tu-viaje/cuando-llega (run a regex over the HTML source).
Step 2: Get the data from https://www.red.cl/predictor/prediccion passing t and codsimt.
Step 3: Transform the data to make it similar to sclstrans's next_arrivals implementation (docs).

Wrangler

This project was generated with wrangler.

Further documentation for Wrangler can be found here.