const request = require('request');
const regression = require('regression');

const old_url = 'https://gisanddata.maps.arcgis.com/sharing/rest/content/items/bda7594740fd40299423467b48e9ecf6/data?f=json';
const base_url = "https://services1.arcgis.com/0MSEUqKaxRlEPj5g/arcgis/rest/services/cases_time/FeatureServer/0/query?f=json";
const date_arg = "&where=Report_Date%3C%3D%272020-02-02 22:59:59%27";
const more_arg = "&returnGeometry=false&spatialRel=esriSpatialRelIntersects&outFields=*&orderByFields=Report_Date%20asc&resultOffset=0&resultRecordCount=2000&cacheHint=true";


module.exports = function(){
	return new Promise((resolve, reject)=>{

		request(base_url + date_arg + more_arg, function (error, response, body) {
		  if(response.statusCode == 200){
		  	const cnt = JSON.parse(body);
		  	//console.log('body:',cnt.features); // Print the HTML for the Google homepage.
		  	var data = [[0,0]];
		  	for (var dp of cnt.features) {
		  		if(dp.attributes.Total_Confirmed != null){
			  		data.push([dp.attributes.ObjectId, dp.attributes.Total_Confirmed]);
		  		}
		  	}
		  	var cur_result = regression.polynomial(data, { order: 3 });
		  	resolve(cur_result.predict(cnt.features.length))
		  }else{
		  	reject(error);
		  }
		});
	});
}