webapi-eca/js/eventpoller.js

// # Event Poller

'use strict';

if(process.argv.length < 3) {
  log.error('EP', 'No DB port defined! Not starting poller...');
} else {
  (function() {
    var fs = require('fs'),
      path = require('path'),
      log = require('./logging'),
      db = require('./db_interface'),
      ml = require('./module_loader'),
      listMessageActions = {},
      listAdminCommands = {},
      listEventModules = {},
      listPoll = {},  //TODO this will change in the future because it could have
                      //several parameterized (user-specific) instances of each event module 
      isRunning = true,
      eId = 0;
    //TODO allow different polling intervals (a wrapper together with settimeout per to be polled could be an easy and solution)
    
    db.init(process.argv[2], process.argv[3]);
    
    //TODO eventpoller will not load event modules from filesystem, this will be done by
    // the moduel manager and the eventpoller receives messages about new/updated active rules 
    
    db.getEventModules(function(err, obj) {
      if(err) log.error('EP', 'retrieving Event Modules from DB!');
      else {
        if(!obj) {
          log.print('EP', 'No Event Modules found in DB!');
          process.send({ event: 'ep_finished_loading' });
        } else {
          var m, semaphore = 0;
          for(var el in obj) {
            semaphore++;
            m = ml.requireFromString(obj[el], el);
            db.getEventModuleAuth(el, function(mod) {
              return function(err, obj) {
                if(--semaphore === 0) process.send({ event: 'ep_finished_loading' });
                if(obj && mod.loadCredentials) mod.loadCredentials(JSON.parse(obj));
              };
            }(m));
            log.print('EP', 'Loading Event Module: ' + el);
            listEventModules[el] = m;
          }
        }
      }
    });
    
    listMessageActions['event'] = function(args) {
      var prop = args[1], arrModule = prop.split('->');
      // var arrModule = obj.module.split('->');
      if(arrModule.length > 1){
        var module = listEventModules[arrModule[0]];
        for(var i = 1; i < arrModule.length; i++) {
          if(module) module = module[arrModule[i]];
        }
        if(module) {
          log.print('EP', 'Found active event module "' + prop + '", adding it to polling list');
          //FIXME change this to [module][prop] = module; because like this identical properties get overwritten
          // also add some on a per user basis information because this should go into a user context for the users
          // that sat up this rule!
          listPoll[prop] = module;
        } else {
          log.print('EP', 'No property "' + prop + '" found');
        }
      }
    };
    
    listAdminCommands['loadevent'] = function(args) {
      ml.loadModule('mod_events', args[2], loadEventCallback);
    };
    
    listAdminCommands['loadevents'] = function(args) {
      ml.loadModules('mod_events', loadEventCallback);
    };
    
    listAdminCommands['shutdown'] = function(args) {
      log.print('EP', 'Shutting down DB Link');
      isRunning = false;
      db.shutDown();
    };
    
    //TODO this goes into module_manager, this will receive notification about
    // new loaded/stored event modules and fetch them from the db
    listMessageActions['cmd'] = function(args) {
      var func = listAdminCommands[args[1]];
      if(typeof(func) === 'function') func(args);
    };
    
    process.on('message', function(strProps) {
      var arrProps = strProps.split('|');
      if(arrProps.length < 2) log.error('EP', 'too few parameter in message!');
      else {
        var func = listMessageActions[arrProps[0]];
        if(func) func(arrProps);
      }
    });
    function loadEventCallback(name, data, mod, auth) {
      db.storeEventModule(name, data); // store module in db
      if(auth) db.storeEventModuleAuth(name, auth);
      listEventModules[name] = mod; // store compiled module for polling
    }
    
    function checkRemotes() {
      for(var prop in listPoll) {
        try {
          listPoll[prop](
          /*
           * define and immediately call anonymous function with param prop.
           * This places the value of prop into the context of the callback
           * and thus doesn't change when the for loop keeps iterating over listPoll
           */
            (function(p) {
              return function(err, obj) {
                if(err) {
                  err.additionalInfo = 'module: ' + p;
                  log.error('EP', err);
                } else {
                  process.send({
                    event: p,
                    eventid: 'polled_' + eId++,
                    data: obj
                  });
                }
              };
            })(prop)
          );
        } catch (e) {
          log.error('EP', e);
        }
      }
    }
    
    function pollLoop() {
      if(isRunning) {
        checkRemotes();
        setTimeout(pollLoop, 10000);
      }
    }

    pollLoop();
  })();
}