Recording-Hook "before" ist nicht wirklich before, oder?

#!/usr/bin/node


//this script watches the vdr timers.conf for changes including touches.
//In the end it can deliver the number of needed recievers (real conflicting recordings!) or an array of 
//parallel running recordings (not necessarly conflicting in the view of recievers!) for the time the timers.conf
//was changed lastly.
//
//The script depends on a working nodejs environment.
//For deamonized running this scrip use for example 'forever'
//
//before using this script "hot", you should examine, if fs.watchFile behaves as expected
//
// file to watch in yaVDR /var/lib/vdr/timers.conf


var http= require('http');
var exec = require("child_process").exec;
var async= require('async');  //needs to be installed separatedly ex. 'npm install async' 
var fs = require('fs'); 
var _ = require('underscore'); //needs to be installed separatedly
var vdr_host = 'localhost';


//watch timers.conf for changes
//the "main"-part ... goes into deep chaos looking code ...
fs.watchFile('/var/lib/vdr/timers.conf', function (curr, prev) {
  if ((curr.mtime.getTime() - prev.mtime.getTime()) > 16500){
	// first action is to get timers from restfull-api and store as json.object
	setTimeout(function() {
	var options = {
   	hostname:vdr_host,
   	path: '/timers.json',
   	port:8002,
   	method:'GET'
	};
	var req = http.request(options, function(res) {
   	var body = '';
   	res.on('data', function(d) {
       	body += d;
   	});
   	res.on('end', function() {
       	var parsed = JSON.parse(body);
       	do_something(parsed.timers); // we have the timers ... now do something 
   	});
	});
	req.end();
	}, 15000); //timeout ende ... sleep for some milliseconds to get multiple changes in timers.conf
  }
});


//end watching-part


function do_something(timers) {
   var pending = _.where(timers, {is_pending: true});
   var log_time = new Date().toISOString().replace('T', ' ').substr(0, 19)   


   get_channels('', function (channels){                           	//we need channels/transponders for conflict detection
  	get_transponders(pending,channels,function(used_transponders){   //add the transponder info on the pending timers
     	// in pending are the timers which are now 'is_pending=true' on restful api
     	// vdr sets 'is_pending=true' BEFORE actually starting the recording
     	// so this should be the perfect BEFORE-recording_hook. 
     	// in used_transponders are the actually needed transponders.
     	// here you should put whatever you wish to do.
     	// as example we print to stdout ... you may call a shell script to start another reciever
     	console.log('******* timers.conf change at time: '+log_time);
     	console.log('Pending timers: '+pending.length);
     	console.log(pending);
     	console.log('Needed recievers: '+used_transponders.length);
     	if (used_transponders.length > 1){
        	var cmd = '/home/ralf/dev/sundtek_on_from_js.sh';
        	console.log('Need more transponder...');
        	child = exec(cmd, function (error, stdout, stderr) {
          	if (error !== null) {
             	console.log("exec error: " + error);
             	return;
          	}
          	if (stderr !== ""){
             	console.log("script exec error: " + stderr);
             	return;
          	}
        	});
     	} //ende if mount more
     	if (used_transponders.length == 1){
        	var cmd = '/home/ralf/dev/sundtek_off.sh';
        	console.log('Maybe switch off transponder...');
        	child = exec(cmd, function (error, stdout, stderr) {
          	if (error !== null) {
             	console.log("exec error: " + error);
             	return;
          	}
          	if (stderr !== ""){
             	console.log("script exec error: " + stderr);
             	return;
          	}
        	});
     	} //ende if switch off
  	});
   });
};




function get_channels(param,callback){
   //nothing special here ... just a http.get on restfull api for channels in a json-object
   var options = {
 	hostname:vdr_host,
 	path: '/channels.json',
 	port:8002,
 	method:'GET' };


  var req = http.request(options, function(res) {
 	var body = '';
 	res.on('data', function(d) {
     	body += d;
 	});
 	res.on('end', function() {
     	var parsed = JSON.parse(body);
     	callback(parsed.channels);
 	});
  });
  req.end();
};


function get_transponders(timers,channels,callback){
   var used =[];
   async.each(timers, function work(timer,callback){
  	transponder = _.findWhere(channels, {name: timer.channel_name}).transponder;
  	timer.transponder=transponder;
  	used.push(transponder);
  	callback();
   }, //1st async end 1st function / parameter
 	function(err){
   	//kick doubles
   	//multiple timers can use the same transponder -> no extra reciever needed
   	used_clear = used.filter(function(elem, pos) {
      	return used.indexOf(elem) == pos;
   	})
   	callback(used_clear);
 	}
   );//end async
}; //end function