utils.js

function match(s, regex, patternNo) {
    if (!s) {
        return;
    }
    const m = String(s).match(regex);
    if (m && patternNo !== undefined) {
        return m[patternNo];
    } else {
        return m;
    }
};
// what file extension the file should be saved to disk
function extensionForSource(source) {
    if (source.zip) { 
        return 'zip';
    } else {
        const format = formatForSource(source)
        return format === 'shp' ? 'zip' : format;
    }
};
// what format the file is ultimately in
function formatForSource(source) {
    const url = source.download;
    let format = source.format;
    if (!format) {
        format = match(url, /\.([a-z]+)$/i, 1);
    }
    if (format === 'zip') {
        format = 'shp';
    }
    if (!format) {
        if (match(url, /(shp$|format=shp|\.shp|\.zip)/)) {
            format = 'shp';
        } else if (match(url, /(csv$|format=csv|\.csv)/)) {
            format = 'csv';
        } else if (match(url, /(json$|format=json|geojson$|format=geojson|\.geojson|\.json)/)) {
            format = 'geojson';
        }
    }
        
    if (format === 'json') {
        format = 'geojson';
    }
    if (!format && source.keepExtension) {
        format = url.match(/\.([^.]+)$/)[1];
    }
    return format;

}
module.exports = {
    match,
    formatForSource,
    extensionForSource
};