function sub(type,handler){
    if(!handler){
        var err=new ReferenceError('handler not defined');
        throw(err);
    }

    checkScope.apply(this);

    if(!this._events_[type])
        this._events_[type]=[];

    this._events_[type].push(handler);
}

function unsub(type,handler){
    if(!handler){
        var err=new ReferenceError('handler not defined. if you wish to remove all handlers from the event please pass "*" as the handler');
        throw err;
    }
    checkScope.apply(this);

    if(handler=='*'){
        delete this._events_[type];
        return;
    }

    if(!this._events_[type])
        return;

    for(var i=0,
            count=this._events_[type].length;
        i<count;
        i++
    ){
        if(this._events_[type][i]==handler){
            this._events_[type].splice(i,1);
        }
    }

    if(this._events_[type].length<1){
        delete this._events_[type];
    }
}

function pub(type){
    checkScope.apply(this);

    if(this._events_['*'] && type!='*'){
        var params=Array.prototype.slice.call(arguments);
        params.unshift('*');
        this.trigger.apply(this,params);
    }

    if(!this._events_[type])
        return;

    for(var i=0,
            events=this._events_[type],
            count=events.length,
            args=Array.prototype.slice.call(arguments,1);
    i<count;
    i++){
        events[i].apply(this, args);
    }
}

function checkScope(){
    if(!this._events_)
        this._events_={};
}

function init(scope){
    if(!scope)
        return {
            on:sub,
            off:unsub,
            trigger:pub
        };

    scope.on=(
        function(scope){
            return function(){
                sub.apply(
                    scope,
                    Array.prototype.slice.call(arguments)
                );
            }
        }
    )(scope);

    scope.off=(
        function(scope){
            return function(){
                unsub.apply(
                    scope,
                    Array.prototype.slice.call(arguments)
                );
            }
        }
    )(scope);

    scope.trigger=(
        function(scope){
            return function(){
                pub.apply(
                    scope,
                    Array.prototype.slice.call(arguments)
                );
            }
        }
    )(scope);

    scope._events_={};
}

module.exports=init