class Communication {
    constructor(interval, ocu, occ, oiu) {
        // Register callbacks
        this.on_candle_update = ocu;
        this.on_candle_close = occ;
        this.on_indctr_update = oiu;
        // Open connections.
        this.set_app_con();
        this.set_exchange_con(interval);
    }

    candle_update(new_candle){
        this.on_candle_update(new_candle);
    }

    candle_close(new_candle){
        // Send a copy of the data to the server
        this.app_con.send( JSON.stringify({ message_type: "candle_data", data :new_candle }));
        this.on_candle_close(new_candle);
    }

    indicator_update(data){
        this.this.on_indctr_update(data);
    }

    set_app_con(){
        // Create a web socket connection to our app.
        this.app_con = new WebSocket('ws://localhost:5000/ws');
        this.app_con.onopen = () => this.app_con.send("Connection OK");

        this.app_con.addEventListener('message', ev => {
            if(ev.data){
                // Get the message received from server
                let msg = JSON.parse(ev.data)
                // Handle a request from the server
                if (msg.request) {
                    //handle request
                    console.log('Received a request from the server');
                    console.log(msg.request);
                }
                // Handle a reply from the server
                if (msg.reply) {
                    // Handle indicator updates
                    if (msg.reply == 'i_updates'){
                       // console.log(msg.data);
                        this.indicator_update(msg.data)
                    }
                }
            }
        })
    }

    set_exchange_con(interval){
        let ws = "wss://stream.binance.com:9443/ws/btcusdt@kline_" + interval;
        this.exchange_con = new WebSocket(ws);

        // Set the on-message call-back for the socket
        this.exchange_con.onmessage = (event) => {
            // Convert message to json obj
    	    let message = JSON.parse(event.data);
    	    // Isolate the candle data from message
    	    let candlestick = message.k;
    	    //console.log(message.k)
            // Reformat data for lightweight charts
            let new_candle={
    		    time: candlestick.t / 1000,
    		    open: candlestick.o,
    		    high: candlestick.h,
    		    low: candlestick.l,
    		    close: candlestick.c,
    		    vol: candlestick.v
    	    };
            // Update frequently updated objects
            this.candle_update(new_candle);
            // Update less frequently updated objects.
            if (candlestick.x == true) { this.candle.close(new_candle); }
        }
    }
}