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app.js
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app.js
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var express = require("express");
var moment = require("moment");
var http = require('http');
var request = require('request');
var fs = require('fs');
var Q = require('q');
var cors = require('cors');
var app = express();
var port = process.env.PORT || 7000;
var baseDir ='http://nomads.ncep.noaa.gov/cgi-bin/filter_gfs_1p00.pl';
// cors config
var whitelist = [
'http://localhost:63342',
'http://localhost:3000',
'http://localhost:4000',
'http://danwild.github.io'
];
var corsOptions = {
origin: function(origin, callback){
var originIsWhitelisted = whitelist.indexOf(origin) !== -1;
callback(null, originIsWhitelisted);
}
};
app.listen(port, function(err){
console.log("running server on port "+ port);
});
app.get('/', cors(corsOptions), function(req, res){
res.send('hello wind-js-server.. go to /latest for wind data..');
});
app.get('/alive', cors(corsOptions), function(req, res){
res.send('wind-js-server is alive');
});
app.get('/latest', cors(corsOptions), function(req, res){
/**
* Find and return the latest available 6 hourly pre-parsed JSON data
*
* @param targetMoment {Object} UTC moment
*/
function sendLatest(targetMoment){
var stamp = moment(targetMoment).format('YYYYMMDD') + roundHours(moment(targetMoment).hour(), 6);
var fileName = __dirname +"/json-data/"+ stamp +".json";
res.setHeader('Content-Type', 'application/json');
res.sendFile(fileName, {}, function (err) {
if (err) {
console.log(stamp +' doesnt exist yet, trying previous interval..');
sendLatest(moment(targetMoment).subtract(6, 'hours'));
}
});
}
sendLatest(moment().utc());
});
app.get('/nearest', cors(corsOptions), function(req, res, next){
var time = req.query.timeIso;
var limit = req.query.searchLimit;
var searchForwards = false;
/**
* Find and return the nearest available 6 hourly pre-parsed JSON data
* If limit provided, searches backwards to limit, then forwards to limit before failing.
*
* @param targetMoment {Object} UTC moment
*/
function sendNearestTo(targetMoment){
if( limit && Math.abs( moment.utc(time).diff(targetMoment, 'days')) >= limit) {
if(!searchForwards){
searchForwards = true;
sendNearestTo(moment(targetMoment).add(limit, 'days'));
return;
}
else {
return next(new Error('No data within searchLimit'));
}
}
var stamp = moment(targetMoment).format('YYYYMMDD') + roundHours(moment(targetMoment).hour(), 6);
var fileName = __dirname +"/json-data/"+ stamp +".json";
res.setHeader('Content-Type', 'application/json');
res.sendFile(fileName, {}, function (err) {
if(err) {
var nextTarget = searchForwards ? moment(targetMoment).add(6, 'hours') : moment(targetMoment).subtract(6, 'hours');
sendNearestTo(nextTarget);
}
});
}
if(time && moment(time).isValid()){
sendNearestTo(moment.utc(time));
}
else {
return next(new Error('Invalid params, expecting: timeIso=ISO_TIME_STRING'));
}
});
/**
*
* Ping for new data every 15 mins
*
*/
setInterval(function(){
run(moment.utc());
}, 900000);
/**
*
* @param targetMoment {Object} moment to check for new data
*/
function run(targetMoment){
getGribData(targetMoment).then(function(response){
if(response.stamp){
convertGribToJson(response.stamp, response.targetMoment);
}
});
}
/**
*
* Finds and returns the latest 6 hourly GRIB2 data from NOAAA
*
* @returns {*|promise}
*/
function getGribData(targetMoment){
var deferred = Q.defer();
function runQuery(targetMoment){
// only go 2 weeks deep
if (moment.utc().diff(targetMoment, 'days') > 30){
console.log('hit limit, harvest complete or there is a big gap in data..');
return;
}
var stamp = moment(targetMoment).format('YYYYMMDD') + roundHours(moment(targetMoment).hour(), 6);
request.get({
url: baseDir,
qs: {
file: 'gfs.t'+ roundHours(moment(targetMoment).hour(), 6) +'z.pgrb2.1p00.f000',
lev_10_m_above_ground: 'on',
lev_surface: 'on',
var_TMP: 'on',
var_UGRD: 'on',
var_VGRD: 'on',
leftlon: 0,
rightlon: 360,
toplat: 90,
bottomlat: -90,
dir: '/gfs.'+stamp
}
}).on('error', function(err){
// console.log(err);
runQuery(moment(targetMoment).subtract(6, 'hours'));
}).on('response', function(response) {
console.log('response '+response.statusCode + ' | '+stamp);
if(response.statusCode != 200){
runQuery(moment(targetMoment).subtract(6, 'hours'));
}
else {
// don't rewrite stamps
if(!checkPath('json-data/'+ stamp +'.json', false)) {
console.log('piping ' + stamp);
// mk sure we've got somewhere to put output
checkPath('grib-data', true);
// pipe the file, resolve the valid time stamp
var file = fs.createWriteStream("grib-data/"+stamp+".f000");
response.pipe(file);
file.on('finish', function() {
file.close();
deferred.resolve({stamp: stamp, targetMoment: targetMoment});
});
}
else {
console.log('already have '+ stamp +', not looking further');
deferred.resolve({stamp: false, targetMoment: false});
}
}
});
}
runQuery(targetMoment);
return deferred.promise;
}
function convertGribToJson(stamp, targetMoment){
// mk sure we've got somewhere to put output
checkPath('json-data', true);
var exec = require('child_process').exec, child;
child = exec('converter/bin/grib2json --data --output json-data/'+stamp+'.json --names --compact grib-data/'+stamp+'.f000',
{maxBuffer: 500*1024},
function (error, stdout, stderr){
if(error){
console.log('exec error: ' + error);
}
else {
console.log("converted..");
// don't keep raw grib data
exec('rm grib-data/*');
// if we don't have older stamp, try and harvest one
var prevMoment = moment(targetMoment).subtract(6, 'hours');
var prevStamp = prevMoment.format('YYYYMMDD') + roundHours(prevMoment.hour(), 6);
if(!checkPath('json-data/'+ prevStamp +'.json', false)){
console.log("attempting to harvest older data "+ stamp);
run(prevMoment);
}
else {
console.log('got older, no need to harvest further');
}
}
});
}
/**
*
* Round hours to expected interval, e.g. we're currently using 6 hourly interval
* i.e. 00 || 06 || 12 || 18
*
* @param hours
* @param interval
* @returns {String}
*/
function roundHours(hours, interval){
if(interval > 0){
var result = (Math.floor(hours / interval) * interval);
return result < 10 ? '0' + result.toString() : result;
}
}
/**
* Sync check if path or file exists
*
* @param path {string}
* @param mkdir {boolean} create dir if doesn't exist
* @returns {boolean}
*/
function checkPath(path, mkdir) {
try {
fs.statSync(path);
return true;
} catch(e) {
if(mkdir){
fs.mkdirSync(path);
}
return false;
}
}
// init harvest
run(moment.utc());