engine/exchange manager: Add support for custom exchanges (#749)

* engine: Setup exchange manager earlier

So it's available for applications before starting.

* engine: Add a custom exchange builder interface

Allows applications that import GCT as a lib to build new
custom exchanges without further modifications.

engine/engine.go

@@ -105,6 +105,8 @@ func NewFromSettings(settings *Settings, flagSet map[string]bool) (*Engine, erro
 		return nil, fmt.Errorf("failed to create script manager. Err: %s", err)
 	}
 
+	b.ExchangeManager = SetupExchangeManager()
+
 	validateSettings(&b, settings, flagSet)
 
 	return &b, nil
@@ -363,7 +365,6 @@ func (bot *Engine) Start() error {
 		bot.Config.PurgeExchangeAPICredentials()
 	}
 
-	bot.ExchangeManager = SetupExchangeManager()
 	gctlog.Debugln(gctlog.Global, "Setting up exchanges..")
 	err = bot.SetupExchanges()
 	if err != nil {

engine/exchange_manager.go

@@ -45,10 +45,17 @@ var (
 	ErrExchangeFailedToLoad  = errors.New("exchange failed to load")
 )
 
+// CustomExchangeBuilder interface allows external applications to create
+// custom/unsupported exchanges that satisfy the IBotExchange interface.
+type CustomExchangeBuilder interface {
+	NewExchangeByName(name string) (exchange.IBotExchange, error)
+}
+
 // ExchangeManager manages what exchanges are loaded
 type ExchangeManager struct {
 	m         sync.Mutex
 	exchanges map[string]exchange.IBotExchange
+	Builder   CustomExchangeBuilder
 }
 
 // SetupExchangeManager creates a new exchange manager
@@ -183,6 +190,9 @@ func (m *ExchangeManager) NewExchangeByName(name string) (exchange.IBotExchange,
 	case "zb":
 		exch = new(zb.ZB)
 	default:
+		if m.Builder != nil {
+			return m.Builder.NewExchangeByName(nameLower)
+		}
 		return nil, fmt.Errorf("%s, %w", nameLower, ErrExchangeNotFound)
 	}
 

engine/exchange_manager_test.go

@@ -1,10 +1,13 @@
 package engine
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 
+	exchange "github.com/thrasher-corp/gocryptotrader/exchanges"
 	"github.com/thrasher-corp/gocryptotrader/exchanges/bitfinex"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/sharedtestvalues"
 )
 
 func TestSetupExchangeManager(t *testing.T) {
@@ -79,3 +82,34 @@ func TestNewExchangeByName(t *testing.T) {
 		}
 	}
 }
+
+type ExchangeBuilder struct{}
+
+func (n ExchangeBuilder) NewExchangeByName(name string) (exchange.IBotExchange, error) {
+	var exch exchange.IBotExchange
+
+	switch name {
+	case "customex":
+		exch = new(sharedtestvalues.CustomEx)
+	default:
+		return nil, fmt.Errorf("%s, %w", name, ErrExchangeNotFound)
+	}
+
+	return exch, nil
+}
+
+func TestNewCustomExchangeByName(t *testing.T) {
+	m := SetupExchangeManager()
+	m.Builder = ExchangeBuilder{}
+	name := "customex"
+	exch, err := m.NewExchangeByName(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err == nil {
+		exch.SetDefaults()
+		if !strings.EqualFold(exch.GetName(), name) {
+			t.Error("did not load expected exchange")
+		}
+	}
+}

exchanges/sharedtestvalues/customex.go

@@ -0,0 +1,283 @@
+package sharedtestvalues
+
+import (
+	"sync"
+	"time"
+
+	"github.com/thrasher-corp/gocryptotrader/config"
+	"github.com/thrasher-corp/gocryptotrader/currency"
+	exchange "github.com/thrasher-corp/gocryptotrader/exchanges"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/account"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/asset"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/kline"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/order"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/orderbook"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/stream"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/ticker"
+	"github.com/thrasher-corp/gocryptotrader/exchanges/trade"
+	"github.com/thrasher-corp/gocryptotrader/portfolio/withdraw"
+)
+
+type CustomEx struct {
+	exchange.Base
+}
+
+func (c *CustomEx) Setup(exch *config.ExchangeConfig) error {
+	return nil
+}
+
+func (c *CustomEx) Start(wg *sync.WaitGroup) {
+}
+
+func (c *CustomEx) SetDefaults() {
+}
+
+func (c *CustomEx) GetName() string {
+	return "customex"
+}
+
+func (c *CustomEx) IsEnabled() bool {
+	return true
+}
+
+func (c *CustomEx) SetEnabled(bool) {
+}
+
+func (c *CustomEx) ValidateCredentials(a asset.Item) error {
+	return nil
+}
+
+func (c *CustomEx) FetchTicker(p currency.Pair, a asset.Item) (*ticker.Price, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) UpdateTicker(p currency.Pair, a asset.Item) (*ticker.Price, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) FetchOrderbook(p currency.Pair, a asset.Item) (*orderbook.Base, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) UpdateOrderbook(p currency.Pair, a asset.Item) (*orderbook.Base, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) FetchTradablePairs(a asset.Item) ([]string, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) UpdateTradablePairs(forceUpdate bool) error {
+	return nil
+}
+
+func (c *CustomEx) GetEnabledPairs(a asset.Item) (currency.Pairs, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) GetAvailablePairs(a asset.Item) (currency.Pairs, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) FetchAccountInfo(a asset.Item) (account.Holdings, error) {
+	return account.Holdings{}, nil
+}
+
+func (c *CustomEx) UpdateAccountInfo(a asset.Item) (account.Holdings, error) {
+	return account.Holdings{}, nil
+}
+
+func (c *CustomEx) GetAuthenticatedAPISupport(endpoint uint8) bool {
+	return false
+}
+
+func (c *CustomEx) SetPairs(pairs currency.Pairs, a asset.Item, enabled bool) error {
+	return nil
+}
+
+func (c *CustomEx) GetAssetTypes(enabled bool) asset.Items {
+	return nil
+}
+
+func (c *CustomEx) GetRecentTrades(p currency.Pair, a asset.Item) ([]trade.Data, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) GetHistoricTrades(p currency.Pair, a asset.Item, startTime, endTime time.Time) ([]trade.Data, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) SupportsAutoPairUpdates() bool {
+	return false
+}
+
+func (c *CustomEx) SupportsRESTTickerBatchUpdates() bool {
+	return false
+}
+
+func (c *CustomEx) GetFeeByType(f *exchange.FeeBuilder) (float64, error) {
+	return 0.0, nil
+}
+
+func (c *CustomEx) GetLastPairsUpdateTime() int64 {
+	return 0
+}
+
+func (c *CustomEx) GetWithdrawPermissions() uint32 {
+	return 0
+}
+
+func (c *CustomEx) FormatWithdrawPermissions() string {
+	return ""
+}
+
+func (c *CustomEx) SupportsWithdrawPermissions(permissions uint32) bool {
+	return false
+}
+
+func (c *CustomEx) GetFundingHistory() ([]exchange.FundHistory, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) SubmitOrder(s *order.Submit) (order.SubmitResponse, error) {
+	return order.SubmitResponse{}, nil
+}
+
+func (c *CustomEx) ModifyOrder(action *order.Modify) (order.Modify, error) {
+	return order.Modify{}, nil
+}
+
+func (c *CustomEx) CancelOrder(o *order.Cancel) error {
+	return nil
+}
+
+func (c *CustomEx) CancelBatchOrders(o []order.Cancel) (order.CancelBatchResponse, error) {
+	return order.CancelBatchResponse{}, nil
+}
+
+func (c *CustomEx) CancelAllOrders(orders *order.Cancel) (order.CancelAllResponse, error) {
+	return order.CancelAllResponse{}, nil
+}
+
+func (c *CustomEx) GetOrderInfo(orderID string, pair currency.Pair, assetType asset.Item) (order.Detail, error) {
+	return order.Detail{}, nil
+}
+
+func (c *CustomEx) GetDepositAddress(cryptocurrency currency.Code, accountID string) (string, error) {
+	return "", nil
+}
+
+func (c *CustomEx) GetOrderHistory(getOrdersRequest *order.GetOrdersRequest) ([]order.Detail, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) GetWithdrawalsHistory(code currency.Code) ([]exchange.WithdrawalHistory, error) {
+	return []exchange.WithdrawalHistory{}, nil
+}
+
+func (c *CustomEx) GetActiveOrders(getOrdersRequest *order.GetOrdersRequest) ([]order.Detail, error) {
+	return []order.Detail{}, nil
+}
+
+func (c *CustomEx) WithdrawCryptocurrencyFunds(withdrawRequest *withdraw.Request) (*withdraw.ExchangeResponse, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) WithdrawFiatFunds(withdrawRequest *withdraw.Request) (*withdraw.ExchangeResponse, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) WithdrawFiatFundsToInternationalBank(withdrawRequest *withdraw.Request) (*withdraw.ExchangeResponse, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) SetHTTPClientUserAgent(ua string) {
+}
+
+func (c *CustomEx) GetHTTPClientUserAgent() string {
+	return ""
+}
+
+func (c *CustomEx) SetClientProxyAddress(addr string) error {
+	return nil
+}
+
+func (c *CustomEx) SupportsREST() bool {
+	return true
+}
+
+func (c *CustomEx) GetSubscriptions() ([]stream.ChannelSubscription, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) GetDefaultConfig() (*config.ExchangeConfig, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) GetBase() *exchange.Base {
+	return nil
+}
+
+func (c *CustomEx) SupportsAsset(assetType asset.Item) bool {
+	return false
+}
+
+func (c *CustomEx) GetHistoricCandles(p currency.Pair, a asset.Item, timeStart, timeEnd time.Time, interval kline.Interval) (kline.Item, error) {
+	return kline.Item{}, nil
+}
+
+func (c *CustomEx) GetHistoricCandlesExtended(p currency.Pair, a asset.Item, timeStart, timeEnd time.Time, interval kline.Interval) (kline.Item, error) {
+	return kline.Item{}, nil
+}
+
+func (c *CustomEx) DisableRateLimiter() error {
+	return nil
+}
+
+func (c *CustomEx) EnableRateLimiter() error {
+	return nil
+}
+
+func (c *CustomEx) GetWebsocket() (*stream.Websocket, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) IsWebsocketEnabled() bool {
+	return false
+}
+
+func (c *CustomEx) SupportsWebsocket() bool {
+	return false
+}
+
+func (c *CustomEx) SubscribeToWebsocketChannels(channels []stream.ChannelSubscription) error {
+	return nil
+}
+
+func (c *CustomEx) UnsubscribeToWebsocketChannels(channels []stream.ChannelSubscription) error {
+	return nil
+}
+
+func (c *CustomEx) IsAssetWebsocketSupported(aType asset.Item) bool {
+	return false
+}
+
+func (c *CustomEx) FlushWebsocketChannels() error {
+	return nil
+}
+
+func (c *CustomEx) AuthenticateWebsocket() error {
+	return nil
+}
+
+func (c *CustomEx) GetOrderExecutionLimits(a asset.Item, cp currency.Pair) (*order.Limits, error) {
+	return nil, nil
+}
+
+func (c *CustomEx) CheckOrderExecutionLimits(a asset.Item, cp currency.Pair, price, amount float64, orderType order.Type) error {
+	return nil
+}
+
+func (c *CustomEx) UpdateOrderExecutionLimits(a asset.Item) error {
+	return nil
+}