engine/exchanges: Add GetCurrencyTradeURL wrapper func/gRPC endpoint (#1521)

* beginning the concept

* expands testing and implementations

* test standardisation, expansion

* more

* finish remainder, add rpc func

* lint

* grammar? I barely know her!

* wow i forgot something wow wow wow wow

* rm SendPayload

* enFixio!

* improve binance long-dated support

* update test design, update wrapper funcs

* adds kraken futures, adds bybit support

* fixes SIMPLE bugs

* s is for sucks

* fixed option url x2

* fixed silly test

engine/rpcserver_test.go

@@ -268,6 +268,10 @@ func (f fExchange) GetHistoricCandlesExtended(_ context.Context, p currency.Pair
 	}, nil
 }
 
+func (f fExchange) GetCurrencyTradeURL(_ context.Context, _ asset.Item, _ currency.Pair) (string, error) {
+	return "https://google.com", nil
+}
+
 func (f fExchange) GetMarginRatesHistory(context.Context, *margin.RateHistoryRequest) (*margin.RateHistoryResponse, error) {
 	leet := decimal.NewFromInt(1337)
 	rates := []margin.Rate{
@@ -4290,3 +4294,55 @@ func TestRPCProxyAuthClient(t *testing.T) {
 		})
 	}
 }
+
+func TestGetCurrencyTradeURL(t *testing.T) {
+	t.Parallel()
+	em := NewExchangeManager()
+	exch, err := em.NewExchangeByName("binance")
+	require.NoError(t, err)
+
+	exch.SetDefaults()
+	b := exch.GetBase()
+	b.Name = fakeExchangeName
+	b.Enabled = true
+	b.CurrencyPairs.Pairs = make(map[asset.Item]*currency.PairStore)
+	err = b.CurrencyPairs.Store(asset.Spot, &currency.PairStore{
+		AssetEnabled:  convert.BoolPtr(true),
+		Enabled:       []currency.Pair{currency.NewPair(currency.BTC, currency.USDT)},
+		Available:     []currency.Pair{currency.NewPair(currency.BTC, currency.USDT)},
+		RequestFormat: &currency.PairFormat{Uppercase: true},
+		ConfigFormat:  &currency.PairFormat{Uppercase: true},
+	})
+	require.NoError(t, err)
+
+	fakeExchange := fExchange{
+		IBotExchange: exch,
+	}
+	err = em.Add(fakeExchange)
+	require.NoError(t, err)
+
+	s := RPCServer{Engine: &Engine{ExchangeManager: em}}
+	_, err = s.GetCurrencyTradeURL(context.Background(), nil)
+	assert.ErrorIs(t, err, common.ErrNilPointer)
+
+	req := &gctrpc.GetCurrencyTradeURLRequest{}
+	_, err = s.GetCurrencyTradeURL(context.Background(), req)
+	assert.ErrorIs(t, err, ErrExchangeNameIsEmpty)
+
+	req.Exchange = fakeExchangeName
+	_, err = s.GetCurrencyTradeURL(context.Background(), req)
+	assert.ErrorIs(t, err, asset.ErrNotSupported)
+
+	req.Asset = "spot"
+	_, err = s.GetCurrencyTradeURL(context.Background(), req)
+	assert.ErrorIs(t, err, currency.ErrCurrencyPairEmpty)
+
+	req.Pair = &gctrpc.CurrencyPair{
+		Delimiter: "-",
+		Base:      "btc",
+		Quote:     "usdt",
+	}
+	resp, err := s.GetCurrencyTradeURL(context.Background(), req)
+	assert.NoError(t, err)
+	assert.NotEmpty(t, resp.Url)
+}