Exchange: Poloniex fixes (#537)

* fix panic bug where item type was different intermittently

* fix nonce bug where it requires an actual timestamp for each consecutive call

* add in default case

* Added in type conversion check and check dataset length to continue

exchanges/poloniex/poloniex.go

@@ -785,7 +785,7 @@ func (p *Poloniex) SendAuthenticatedHTTPRequest(method, endpoint string, values
 	headers := make(map[string]string)
 	headers["Content-Type"] = "application/x-www-form-urlencoded"
 	headers["Key"] = p.API.Credentials.Key
-	values.Set("nonce", p.Requester.GetNonce(true).String())
+	values.Set("nonce", strconv.FormatInt(time.Now().UnixNano(), 10))
 	values.Set("command", endpoint)
 
 	hmac := crypto.GetHMAC(crypto.HashSHA512,
@@ -803,7 +803,6 @@ func (p *Poloniex) SendAuthenticatedHTTPRequest(method, endpoint string, values
 		Body:          bytes.NewBufferString(values.Encode()),
 		Result:        result,
 		AuthRequest:   true,
-		NonceEnabled:  true,
 		Verbose:       p.Verbose,
 		HTTPDebugging: p.HTTPDebugging,
 		HTTPRecording: p.HTTPRecording,

exchanges/poloniex/poloniex_websocket.go

@@ -314,11 +314,28 @@ func (p *Poloniex) wsHandleData(respRaw []byte) error {
 						currencyPair := currencyIDMap[channelID]
 						var trade WsTrade
 						trade.Symbol = currencyIDMap[channelID]
-						dataL3 := dataL2.([]interface{})
-						trade.TradeID, err = strconv.ParseInt(dataL3[1].(string), 10, 64)
-						if err != nil {
-							return err
+						dataL3, ok := dataL2.([]interface{})
+						if !ok {
+							return errors.New("websocket trade update error: type conversion failure")
 						}
+
+						if len(dataL3) != 6 {
+							return errors.New("websocket trade update error: incorrect data returned")
+						}
+
+						// tradeID type intermittently changes
+						switch t := dataL3[1].(type) {
+						case string:
+							trade.TradeID, err = strconv.ParseInt(t, 10, 64)
+							if err != nil {
+								return err
+							}
+						case float64:
+							trade.TradeID = int64(t)
+						default:
+							return fmt.Errorf("unhandled type for websocket trade update: %v", t)
+						}
+
 						side := order.Buy
 						if dataL3[2].(float64) != 1 {
 							side = order.Sell