GateIO: Add GetEstimatedInterestRate REST endpoint (#2102)

* gateio: Add func GetEstimatedInterestRate (cherry-pickable)

* Add tests

* Update exchanges/gateio/gateio.go

Co-authored-by: Gareth Kirwan <gbjkirwan@gmail.com>

* Update exchanges/gateio/gateio.go

Co-authored-by: Gareth Kirwan <gbjkirwan@gmail.com>

* gk: nits

* thrasher-: nits

---------

Co-authored-by: Ryan O'Hara-Reid <ryan.oharareid@thrasher.io>
Co-authored-by: Gareth Kirwan <gbjkirwan@gmail.com>

exchanges/gateio/gateio.go

@@ -166,6 +166,7 @@ var (
 	errMissingAPIKey                    = errors.New("missing API key information")
 	errInvalidTextPrefix                = errors.New("invalid text value, requires prefix `t-`")
 	errSingleAssetRequired              = errors.New("single asset type required")
+	errTooManyCurrencyCodes             = errors.New("too many currency codes supplied")
 )
 
 // validTimesInForce holds a list of supported time-in-force values and corresponding string representations.
@@ -1323,6 +1324,31 @@ func (e *Exchange) ConvertSmallBalances(ctx context.Context, currs ...currency.C
 
 // ********************************* Margin *******************************************
 
+// GetEstimatedInterestRate retrieves estimated interest rate for provided currencies
+func (e *Exchange) GetEstimatedInterestRate(ctx context.Context, currencies []currency.Code) (map[string]types.Number, error) {
+	if len(currencies) == 0 {
+		return nil, currency.ErrCurrencyCodesEmpty
+	}
+	if len(currencies) > 10 {
+		return nil, fmt.Errorf("%w: maximum 10", errTooManyCurrencyCodes)
+	}
+	var currStr strings.Builder
+	for i := range currencies {
+		if currencies[i].IsEmpty() {
+			return nil, currency.ErrCurrencyCodeEmpty
+		}
+		if i != 0 {
+			currStr.WriteString(",")
+		}
+		currStr.WriteString(currencies[i].String())
+	}
+	params := url.Values{}
+	params.Set("currencies", currStr.String())
+
+	var response map[string]types.Number
+	return response, e.SendAuthenticatedHTTPRequest(ctx, exchange.RestSpot, marginEstimateRateEPL, http.MethodGet, "margin/uni/estimate_rate", params, nil, &response)
+}
+
 // GetMarginSupportedCurrencyPairs retrieves margin supported currency pairs.
 func (e *Exchange) GetMarginSupportedCurrencyPairs(ctx context.Context) ([]MarginCurrencyPairInfo, error) {
 	var currenciePairsInfo []MarginCurrencyPairInfo

exchanges/gateio/gateio_test.go

@@ -3707,3 +3707,35 @@ func TestUnmarshalJSONOrderbookLevels(t *testing.T) {
 
 	require.Error(t, ob.UnmarshalJSON([]byte(`["p":"123.45","s":"0.001"]`)))
 }
+
+func TestGetEstimatedInterestRate(t *testing.T) {
+	t.Parallel()
+
+	_, err := e.GetEstimatedInterestRate(t.Context(), nil)
+	require.ErrorIs(t, err, currency.ErrCurrencyCodesEmpty)
+
+	_, err = e.GetEstimatedInterestRate(t.Context(), currency.Currencies{currency.EMPTYCODE})
+	require.ErrorIs(t, err, currency.ErrCurrencyCodeEmpty)
+
+	_, err = e.GetEstimatedInterestRate(t.Context(), currency.Currencies{
+		currency.USDT,
+		currency.BTC,
+		currency.ETH,
+		currency.XRP,
+		currency.LTC,
+		currency.DOGE,
+		currency.BCH,
+		currency.SOL,
+		currency.ADA,
+		currency.DOT,
+		currency.MATIC,
+	})
+	require.ErrorIs(t, err, errTooManyCurrencyCodes)
+
+	sharedtestvalues.SkipTestIfCredentialsUnset(t, e)
+	got, err := e.GetEstimatedInterestRate(t.Context(), currency.Currencies{currency.BTC})
+	require.NoError(t, err)
+	val, ok := got["BTC"]
+	require.True(t, ok, "result map must contain BTC key")
+	require.Positive(t, val.Float64(), "estimated interest rate must not be 0")
+}

exchanges/gateio/gateio_types.go

@@ -630,14 +630,14 @@ type CurrencyChain struct {
 
 // MarginCurrencyPairInfo represents margin currency pair detailed info.
 type MarginCurrencyPairInfo struct {
-	ID             string       `json:"id"`
-	Base           string       `json:"base"`
-	Quote          string       `json:"quote"`
-	Leverage       float64      `json:"leverage"`
-	MinBaseAmount  types.Number `json:"min_base_amount"`
-	MinQuoteAmount types.Number `json:"min_quote_amount"`
-	MaxQuoteAmount types.Number `json:"max_quote_amount"`
-	Status         int32        `json:"status"`
+	ID             currency.Pair `json:"id"`
+	Base           currency.Code `json:"base"`
+	Quote          currency.Code `json:"quote"`
+	Leverage       float64       `json:"leverage"`
+	MinBaseAmount  types.Number  `json:"min_base_amount"`
+	MinQuoteAmount types.Number  `json:"min_quote_amount"`
+	MaxQuoteAmount types.Number  `json:"max_quote_amount"`
+	Status         int32         `json:"status"`
 }
 
 // OrderbookOfLendingLoan represents order book of lending loans

exchanges/gateio/gateio_wrapper.go

@@ -432,12 +432,7 @@ func (e *Exchange) FetchTradablePairs(ctx context.Context, a asset.Item) (curren
 			if tradables[x].Status == 0 {
 				continue
 			}
-			p := strings.ToUpper(tradables[x].Base + currency.UnderscoreDelimiter + tradables[x].Quote)
-			cp, err := currency.NewPairFromString(p)
-			if err != nil {
-				return nil, err
-			}
-			pairs = append(pairs, cp)
+			pairs = append(pairs, tradables[x].ID)
 		}
 		return pairs, nil
 	case asset.CoinMarginedFutures, asset.USDTMarginedFutures:

exchanges/gateio/ratelimiter.go

@@ -123,6 +123,7 @@ const (
 	marginGetMaxBorrowCrossEPL
 	marginGetCrossBorrowHistoryEPL
 	marginGetBorrowEPL
+	marginEstimateRateEPL
 
 	flashSwapOrderEPL
 	flashGetOrdersEPL
@@ -312,6 +313,7 @@ var packageRateLimits = request.RateLimitDefinitions{
 	marginGetMaxBorrowCrossEPL:          otherPrivateEndpointRateLimit(),
 	marginGetCrossBorrowHistoryEPL:      otherPrivateEndpointRateLimit(),
 	marginGetBorrowEPL:                  otherPrivateEndpointRateLimit(),
+	marginEstimateRateEPL:               otherPrivateEndpointRateLimit(),
 
 	flashSwapOrderEPL:   otherPrivateEndpointRateLimit(),
 	flashGetOrdersEPL:   otherPrivateEndpointRateLimit(),