export namespace WS {

    export type Events = 'error' | 'message' | 'close' | 'open';


    export interface Data<T = any> {
        timeStamp:number;
        data:T;
    };


    export type DataEventHandler<T = any> = (arg:Data<T>)=>void;
    export type CloseEventHandler = (arg:CloseEvent)=>void;
    export type EventHandler = (arg:Event) => void;

    export class JSONWebsocketClient<T = any> {

        private socket:WebSocket;


        private messageHandler:DataEventHandler<T>;
        private closeHandler:CloseEventHandler;
        private errorHandler:EventHandler;
        private openHandler:EventHandler;

        constructor(ws:string) {
            this.socket = new WebSocket(ws);
            this.socket.onopen = this.onOpen.bind(this);
            this.socket.onclose = this.onClose.bind(this);
            this.socket.onerror = this.onError.bind(this);
            this.socket.onmessage = this.onMessage.bind(this);
        }


        on(event:'message',handler:DataEventHandler<T>):void;
        on(event:'close',handler:CloseEventHandler):void;
        on(event:'open' | 'error',handler:EventHandler):void;


        on(event:Events,handler:DataEventHandler<T> | CloseEventHandler | EventHandler) {
            switch(event) {
                case 'close':
                    this.closeHandler = handler as CloseEventHandler;
                    break;
                case 'open':
                    this.openHandler = handler as EventHandler;
                    break;
                case 'message':
                    this.messageHandler = handler as DataEventHandler<T>;
                    break;
                case 'error':
                    this.errorHandler = handler as EventHandler;
                    break;
            }
        }

        send(data:T) {
            this.socket.send(JSON.stringify(data));
        }


        private onMessage(ev:MessageEvent) {
            const data = JSON.parse(ev.data);
            if(this.messageHandler) {
                this.messageHandler({data:data,timeStamp:ev.timeStamp});
            }
        }
        private onError(ev:Event) {
            if(this.errorHandler) {
                this.errorHandler(ev);
            }
        }

        private onClose(ev:CloseEvent) {
            if(this.closeHandler) {
                this.closeHandler(ev);
            }
        }

        private onOpen(ev:Event) {
            if(this.openHandler) {
                this.openHandler(ev);
            }
        }
    }
}