// cheap event system that handle subscription, unsubscriptions and event emitions
import React from "react";
import { randomString } from "../helpers/";
const emitters = {};

function subscribe(key, event, fn) {
    if (emitters[event]) {
        emitters[event][key] = fn;
    } else {
        emitters[event] = {};
        emitters[event][key] = fn;
    }
}

function unsubscribe(key, event) {
    if (emitters[event]) {
        if (key) {
            delete emitters[event][key];
        } else {
            delete emitters[event];
        }
    }
}

function emit(event, payload) {
    // trigger events if needed
    if (emitters[event]) {
        return Promise.all(Object.keys(emitters[event]).map((key) => {
            return emitters[event][key].apply(null, payload);
        })).then((res) => {
            return emitters[event] ?
                Promise.resolve(res) :
                Promise.reject({ message: "do not exist", code: "CANCELLED" });
        });
    } else {
        return Promise.reject({ message: "oups, something went wrong", code: "NO_LISTENERS" });
    }
}

export function EventReceiver(WrappedComponent) {
    const id = randomString();

    return class extends React.Component {
        subscribe(event, callback) {
            subscribe(id, event, callback);
        }

        unsubscribe(event) {
            unsubscribe(id, event);
        }

        render() {
            return (
                <WrappedComponent subscribe={this.subscribe} unsubscribe={this.unsubscribe}
                    {...this.props} />
            );
        }
    };
}

export function EventEmitter(WrappedComponent) {
    return class extends React.Component {
        emit() {
            // reconstruct arguments
            const args = Array.prototype.slice.call(arguments);
            const event = args.shift();
            const payload = args;

            const res = emit(event, payload);
            if (res.then) {
                return res;
            } else {
                return Promise.resolve(res);
            }
        }

        render() {
            return <WrappedComponent emit={this.emit} {...this.props} />;
        }
    };
}