Minetrack/lib/util.js

var logger = require('./logger');
var dns = require('dns');

var config = require('../config.json');
var servers = require('../servers.json');

var serverNameLookup = [];

var bootTime;

// Finds a server in servers.json with a matching IP.
// If it finds one, it caches the result for faster future lookups.
function getServerNameByIp(ip) {
	var lookupName = serverNameLookup[ip];

	if (lookupName) {
		return lookupName;
	}

	for (var i = 0; i < servers.length; i++) {
		var entry = servers[i];

		if (entry.ip === ip) {
			serverNameLookup[entry.ip] = entry.name;

			return entry.name;
		}
	}
}

// Returns a list of configured server IPs from servers.json
function getServerIps() {
	var ips = [];

	for (var i = 0; i < servers.length; i++) {
		ips.push(servers[i].ip);
	}

	return ips;
}

// This method is a monstrosity.
// Since we loaded ALL pings from the database, we need to filter out the pings so each entry is a minute apart.
// This is done by iterating over the list, since the time between each ping can be completely arbitrary.
function trimUselessPings(data) {
	var keys = Object.keys(data);

	for (var i = 0; i < keys.length; i++) {
		var listing = data[keys[i]];
		var lastTimestamp = 0;

		var filteredListing = [];

		for (var x = 0; x < listing.length; x++) {
			var entry = listing[x];

			// 0 is the index of the timestamp.
			// See the convertPingsToGraph method.
			if (entry[0] - lastTimestamp >= 60 * 1000) {
				// This second check tries to smooth out randomly dropped pings.
				// By default we only want entries that are online (playerCount > 0).
				// This way we'll keep looking forward until we find one that is online.
				// However if we can't find one within a reasonable timeframe, select the sucky one.
				if (entry[0] - lastTimestamp >= 120 * 1000 || entry[1] > 0) {
					filteredListing.push(entry);

					lastTimestamp = entry[0];
				}
			}
		}

		data[keys[i]] = filteredListing;
	}
}

exports.trimOldPings = function(data) {
	var keys = Object.keys(data);

	var timeMs = exports.getCurrentTimeMs();

	for (var x = 0; x < keys.length; x++) {
		var listing = data[keys[x]];
		var toSplice = [];

		for (var i = 0; i < listing.length; i++) {
			var entry = listing[i];

			if (timeMs - entry[0] > config.graphDuration) {
				toSplice.push(i);
			}
		}

		for (var i = 0; i < toSplice.length; i++) {
			listing.splice(toSplice[i], 1);
		}
	}
}

exports.getCurrentTimeMs = function() {
    return new Date().getTime();
};

exports.setIntervalNoDelay = function(func, delay) {
	var task = setInterval(func, delay);

	func();

	return task;
};

exports.convertServerHistory = function(sqlData) {
	var serverIps = getServerIps();
	var graphData = {};

	var startTime = exports.getCurrentTimeMs();

	for (var i = 0; i < sqlData.length; i++) {
		var entry = sqlData[i];

		if (serverIps.indexOf(entry.ip) === -1) continue;

		var name = getServerNameByIp(entry.ip);

		if (!graphData[name]) graphData[name] = [];
		graphData[name].push([entry.timestamp, entry.playerCount]);
	}

	// Break it into minutes.
	trimUselessPings(graphData);

	// Drop old data.
	exports.trimOldPings(graphData);

	logger.info('Parsed ' + sqlData.length + ' ping records in ' + (exports.getCurrentTimeMs() - startTime) + 'ms');

	return graphData;
};

exports.getBootTime = function() {
	if (!bootTime) {
		bootTime = exports.getCurrentTimeMs();

		logger.info('Selected %d as boot time.', bootTime);
	}

	return bootTime;
};

/**
 * Attempts to resolve Minecraft PC SRV records from DNS, otherwise falling back to the old hostname.
 *
 * @param hostname hostname to check
 * @param port port to pass to callback if required
 * @param callback function with a hostname and port parameter
 */
exports.unfurlSRV = function(hostname, port, callback) {
	dns.resolveSrv("_minecraft._tcp."+hostname, function (err, records) {
		if(!records||records.length<=0) {
			callback(hostname, port);
			return;
		}
		callback(records[0].name, records[0].port);
	})
};