var geojsonNormalize = require('@mapbox/geojson-normalize'),
    geojsonFlatten = require('geojson-flatten'),
    flatten = require('./flatten');

if (!(geojsonFlatten instanceof Function)) geojsonFlatten = geojsonFlatten.default;

module.exports = function(_) {
    if (!_) return [];
    var normalized = geojsonFlatten(geojsonNormalize(_)),
        coordinates = [];
    normalized.features.forEach(function(feature) {
        if (!feature.geometry) return;
        coordinates = coordinates.concat(flatten(feature.geometry.coordinates));
    });
    return coordinates;
};