piano/js/libs/flight/lib/logger.js

// ==========================================
// Copyright 2013 Twitter, Inc
// Licensed under The MIT License
// http://opensource.org/licenses/MIT
// ==========================================

define(

  [
    './utils'
  ],

  function(utils) {
    'use strict';

    var actionSymbols = {
      on: '<-',
      trigger: '->',
      off: 'x '
    };

    function elemToString(elem) {
      var tagStr = elem.tagName ? elem.tagName.toLowerCase() : elem.toString();
      var classStr = elem.className ? '.' + (elem.className) : '';
      var result = tagStr + classStr;
      return elem.tagName ? ['\'', '\''].join(result) : result;
    }

    function log(action, component, eventArgs) {
      if (!window.DEBUG || !window.DEBUG.enabled) return;
      var name, eventType, elem, fn, payload, logFilter, toRegExp, actionLoggable, nameLoggable, info;

      if (typeof eventArgs[eventArgs.length-1] == 'function') {
        fn = eventArgs.pop();
        fn = fn.unbound || fn; // use unbound version if any (better info)
      }

      if (eventArgs.length == 1) {
        elem = component.$node[0];
        eventType = eventArgs[0];
      } else if ((eventArgs.length == 2) && typeof eventArgs[1] == 'object' && !eventArgs[1].type) {
        //2 args, first arg is not elem
        elem = component.$node[0];
        eventType = eventArgs[0];
        if (action == "trigger") {
          payload = eventArgs[1];
        }
      } else {
        //2+ args, first arg is elem
        elem = eventArgs[0];
        eventType = eventArgs[1];
        if (action == "trigger") {
          payload = eventArgs[2];
        }
      }

      name = typeof eventType == 'object' ? eventType.type : eventType;

      logFilter = DEBUG.events.logFilter;

      // no regex for you, actions...
      actionLoggable = logFilter.actions == 'all' || (logFilter.actions.indexOf(action) > -1);
      // event name filter allow wildcards or regex...
      toRegExp = function(expr) {
        return expr.test ? expr : new RegExp('^' + expr.replace(/\*/g, '.*') + '$');
      };
      nameLoggable =
        logFilter.eventNames == 'all' ||
        logFilter.eventNames.some(function(e) {return toRegExp(e).test(name);});

      if (actionLoggable && nameLoggable) {
        info = [actionSymbols[action], action, '[' + name + ']'];
        payload && info.push(payload);
        info.push(elemToString(elem));
        info.push(component.constructor.describe.split(' ').slice(0,3).join(' '));
        console.groupCollapsed && action == 'trigger' && console.groupCollapsed(action, name);
        console.info.apply(console, info);
      }
    }

    function withLogging() {
      this.before('trigger', function() {
        log('trigger', this, utils.toArray(arguments));
      });
      if (console.groupCollapsed) {
        this.after('trigger', function() {
          console.groupEnd();
        });
      }
      this.before('on', function() {
        log('on', this, utils.toArray(arguments));
      });
      this.before('off', function() {
        log('off', this, utils.toArray(arguments));
      });
    }

    return withLogging;
  }
);