'use strict';

class EventPubSub {
    constructor(scope){
        this._events_={};
        this.publish=this.trigger=this.emit;
        this.subscribe=this.on;
        this.unSubscribe=this.off;
    }

    on(type,handler){
        if(!handler){
            const err=new ReferenceError('handler not defined.');
            throw(err);
        }

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

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

    off(type,handler){
        if(!this._events_[type]){
            return this;
        }

        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;
        }

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

        const handlers=this._events_[type];

        while(handlers.includes(handler)){
            handlers.splice(
                handlers.indexOf(handler),
                1
            );
        }

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

        return this;
    }

    emit(type,...args){
        if(!this._events_[type]){
            return this.emit$(type,...args);
        }

        const handlers=this._events_[type];

        for(let handler of handlers){
            handler.apply(this, args);
        }

        return this.emit$(type,...args);
    }

    emit$(type,...args){
        if(!this._events_['*']){
            return this;
        }

        const catchAll=this._events_['*'];

        for(let handler of catchAll){
            handler.call(this, type, ...args);
        }

        return this;
    }
}

module.exports=EventPubSub;