// Get CORPUS data from Network Rail and format the data for OwlBoard

// Network Rail Datafeed user and pass must be stored in `/srv/keys/owlboard/keys.config.js`

// FUNCTIONS/
//  initSubset()  : Exported: Uses the internal functions to return a clean CORPUS object.
//  initAll()     : Exported: Uses the internal functions to return a full CORPUS object.
//  get()         : Get the CORPUS data from Network Rail as a gzip file.
//  extract()     : Extract the CORPUS JSON file from the GZIP file.
//  clean()       : Cleans the CORPUS data, removing unneccesary non-stations from the data.

const log      = require('../utils/log.utils');          // Log Helper

const axios  = require('axios')
const gz     = require('node-gzip')

const corpusUser = process.env.OWL_LDB_CORPUSUSER
const corpusPass = process.env.OWL_LDB_CORPUSPASS

async function subset(allCorpus) {
    var cleanCorpus = await clean(allCorpus)
    return cleanCorpus
}

async function get(){
    var gzipData = await fetch()
    var allCorpus = await extract(gzipData)
    return allCorpus
}

async function fetch() {
    log.out("Corpus: Fetching CORPUS Data from Network Rail")
    authHead = Buffer.from(`${corpusUser}:${corpusPass}`).toString('base64')
    const url = 'https://datafeeds.networkrail.co.uk/ntrod/SupportingFileAuthenticate?type=CORPUS'
    const options = {
        method: 'get',
        timeout: 20000,
        headers: {'Authorization': `Basic ${authHead}`},
        responseType: 'arraybuffer'
    }
    try {
        var { data } = await axios.get(url, options)
        log.out("Corpus: CORPUS Data fetched")
    } catch (error) {
        log.out("Corpus: Error fetching CORPUS")
        log.out(error)
    }
    return data
}

async function extract(input) {
    log.out(`Corpus: Extracting CORPUS archive`)
    var raw = await gz.ungzip(input)
    var obj = await JSON.parse(raw)
    var output = obj.TIPLOCDATA
    return output
}

async function clean(input) {
    log.out(`Corpus: Removing non-stations from CORPUS data`)
    let clean = [];
    for (const element of input) {
        if (element.STANOX != ' ' && element['3ALPHA'] != ' '){
            delete(element.UIC);
            delete(element.NLCDESC16);
            delete(element.NLC);
            clean.push(element);
        }
    }
    return clean;
}

module.exports = {
    get,
    subset
}