epub.js/lib/epubjs/hooks.js

EPUBJS.hooks = {};
EPUBJS.Hooks = (function(){
  function hooks(){}
  
  //-- Get pre-registered hooks
  hooks.prototype.getHooks = function(){
    var plugs, hooks;
    this.hooks = {};
    Array.prototype.slice.call(arguments).forEach(function(arg){
      this.hooks[arg] = [];
    }, this);

    for (var plugType in this.hooks) {
      hooks = EPUBJS.hooks[plugType];
      if(hooks){
        plugs = EPUBJS.core.values();
  
        plugs.forEach(function(hook){
          this.registerHook(plugType, hook);
        }, this);
      }
    }
  };
  
  //-- Hooks allow for injecting async functions that must all complete before continuing 
  //   Functions must have a callback as their first argument.
  hooks.prototype.registerHook = function(type, toAdd, toFront){
  
    if(typeof(this.hooks[type]) != "undefined"){
  
      if(typeof(toAdd) === "function"){
        if(toFront) {
          this.hooks[type].unshift(toAdd);
        }else{
          this.hooks[type].push(toAdd);
        }
      }else if(Array.isArray(toAdd)){
        toAdd.forEach(function(hook){
          if(toFront) {
            this.hooks[type].unshift(hook);
          }else{
            this.hooks[type].push(hook);
          }
        }, this);
      }
    }else{
      //-- Allows for undefined hooks, but maybe this should error?
      this.hooks[type] = [func];
    }
  };
  
  hooks.prototype.triggerHooks = function(type, callback, passed){
    var hooks, count;
  
    if(typeof(this.hooks[type]) == "undefined") return false;
  
    hooks = this.hooks[type];
  
    count = hooks.length;
    if(count === 0 && callback) {
      callback();
    }

    function countdown(){
      count--;
      if(count <= 0 && callback) callback();
    }
  
    hooks.forEach(function(hook){
      hook(countdown, passed);
    });
  };
  
  return {
    register: function(name) {
      if(EPUBJS.hooks[name] === undefined) { EPUBJS.hooks[name] = {}; }
      if(typeof EPUBJS.hooks[name] !== 'object') { throw "Already registered: "+name; }
      return EPUBJS.hooks[name];
    },
    mixin: function(object) {
      for (var prop in hooks.prototype) {
        object[prop] = hooks.prototype[prop];
      }
    }
  };
})();