Bitmex: Fix deprecated API endpoints and add config migration support (#1901)

* Bitmex: Fix configured WS url ignored

* Bitmex: Replace deprecated WS api endpoint

* [Bitmex deprecated the old WS multiplexing endpoint](https://blog.bitmex.com/api_announcement/api-update-remove-support-realtimemd/)
* [Bitmex deprecated the www WS endpoint in 2021](https://blog.bitmex.com/api_announcement/change-of-websocket-endpoint/). Apparently still in service though.

Fixes #1894

config/versions/register.go

@@ -9,6 +9,7 @@ import (
 	v5 "github.com/thrasher-corp/gocryptotrader/config/versions/v5"
 	v6 "github.com/thrasher-corp/gocryptotrader/config/versions/v6"
 	v7 "github.com/thrasher-corp/gocryptotrader/config/versions/v7"
+	v8 "github.com/thrasher-corp/gocryptotrader/config/versions/v8"
 )
 
 func init() {
@@ -20,4 +21,5 @@ func init() {
 	Manager.registerVersion(5, &v5.Version{})
 	Manager.registerVersion(6, &v6.Version{})
 	Manager.registerVersion(7, &v7.Version{})
+	Manager.registerVersion(8, &v8.Version{})
 }

config/versions/v8/v8.go

@@ -0,0 +1,43 @@
+package v8
+
+import (
+	"context"
+	"errors"
+
+	"github.com/buger/jsonparser"
+)
+
+// Version is an ExchangeVersion to remove deprecated WS endpoints from user config
+// Announcements:
+// * https://blog.bitmex.com/api_announcement/change-of-websocket-endpoint/
+// * https://blog.bitmex.com/api_announcement/api-update-remove-support-realtimemd/
+type Version struct{}
+
+// Exchanges returns just Bitmex
+func (v *Version) Exchanges() []string { return []string{"Bitmex"} }
+
+// UpgradeExchange replaces deprecated WS endpoints
+func (v *Version) UpgradeExchange(_ context.Context, e []byte) ([]byte, error) {
+	url, err := jsonparser.GetString(e, "api", "urlEndpoints", "WebsocketSpotURL")
+	switch {
+	case errors.Is(err, jsonparser.KeyPathNotFoundError):
+		return e, nil
+	case err != nil:
+		return e, err
+	}
+
+	switch url {
+	case "wss://ws.bitmex.com/realtimemd", "wss://www.bitmex.com/realtimemd", "wss://www.bitmex.com/realtime":
+		// Old defaults, just delete them
+		return jsonparser.Delete(e, "api", "urlEndpoints", "WebsocketSpotURL"), nil
+	case "wss://ws.testnet.bitmex.com/realtimemd", "wss://testnet.bitmex.com/realtimemd", "wss://testnet.bitmex.com/realtime":
+		// User wants to use testnet
+		return jsonparser.Set(e, []byte(`"wss://ws.testnet.bitmex.com/realtime"`), "api", "urlEndpoints", "WebsocketSpotURL")
+	}
+	return e, nil
+}
+
+// DowngradeExchange is a no-op for v8
+func (v *Version) DowngradeExchange(_ context.Context, e []byte) ([]byte, error) {
+	return e, nil
+}

config/versions/v8/v8_test.go

@@ -0,0 +1,56 @@
+package v8_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	v8 "github.com/thrasher-corp/gocryptotrader/config/versions/v8"
+)
+
+func TestExchanges(t *testing.T) {
+	t.Parallel()
+	assert.Equal(t, []string{"Bitmex"}, new(v8.Version).Exchanges())
+}
+
+func TestUpgradeExchange(t *testing.T) {
+	t.Parallel()
+
+	for _, tt := range []struct {
+		in  string
+		exp string
+	}{
+		{"wss://private.bitmex.com/realtimemd", `"WebsocketSpotURL": "wss://private.bitmex.com/realtimemd"`},
+		{"wss://ws.bitmex.com/realtimemd", ""},
+		{"wss://www.bitmex.com/realtimemd", ""},
+		{"wss://www.bitmex.com/realtime", ""},
+		{"wss://ws.testnet.bitmex.com/realtimemd", `"WebsocketSpotURL": "wss://ws.testnet.bitmex.com/realtime"`},
+		{"wss://testnet.bitmex.com/realtimemd", `"WebsocketSpotURL": "wss://ws.testnet.bitmex.com/realtime"`},
+		{"wss://testnet.bitmex.com/realtime", `"WebsocketSpotURL": "wss://ws.testnet.bitmex.com/realtime"`},
+	} {
+		t.Run(tt.in, func(t *testing.T) {
+			t.Parallel()
+			in := []byte(`{"name":"Bitmex","api":{"urlEndpoints":{"WebsocketSpotURL": "` + tt.in + `"}}}`)
+			out, err := new(v8.Version).UpgradeExchange(t.Context(), in)
+			require.NoError(t, err)
+			exp := `{"name":"Bitmex","api":{"urlEndpoints":{` + tt.exp + `}}}`
+			assert.Equal(t, exp, string(out))
+		})
+	}
+
+	in := []byte(`{"name":"Bitmex","api":{}`)
+	out, err := new(v8.Version).UpgradeExchange(t.Context(), in)
+	require.NoError(t, err, "UpgradeExchange must not error when urlEndpoints is missing")
+	assert.Equal(t, string(in), string(out), "UpgradeExchange should return same input not error when urlEndpoints is missing")
+
+	_, err = new(v8.Version).UpgradeExchange(t.Context(), []byte(`{"name":"Bitmex","api":{"urlEndpoints":{"WebsocketSpotURL": 42}}}`))
+	require.ErrorContains(t, err, "Value is not a string", "UpgradeExchange must error correctly on string value")
+}
+
+func TestDowngradeExchange(t *testing.T) {
+	t.Parallel()
+	in := []byte(`{"name":"Bitmex","api":{"urlEndpoints":{"WebsocketSpotURL": 42}}}`)
+	out, err := new(v8.Version).DowngradeExchange(t.Context(), in)
+	require.NoError(t, err)
+	require.Equal(t, string(in), string(out), "DowngradeExchange must not change json")
+}