implement buyandhold strategy to test the api design

pkg/bbgo/account.go

@@ -14,6 +14,13 @@ type Account struct {
 	Balances map[string]types.Balance
 }
 
+func (a *Account) Balance(currency string) (balance types.Balance, ok bool) {
+	a.Lock()
+	balance, ok = a.Balances[currency]
+	a.Unlock()
+	return balance, ok
+}
+
 func (a *Account) handleBalanceUpdates(balances map[string]types.Balance) {
 	a.Lock()
 	defer a.Unlock()
@@ -34,7 +41,7 @@ func (a *Account) Print() {
 
 	for _, balance := range a.Balances {
 		if util.NotZero(balance.Available) {
-			log.Infof("[trader] balance %s %f", balance.Currency, balance.Available)
+			log.Infof("account balance %s %f", balance.Currency, balance.Available)
 		}
 	}
 }

pkg/strategy/buyandhold/main.go

@@ -2,42 +2,82 @@ package buyandhold
 
 import (
 	"context"
+	"encoding/json"
+	"io/ioutil"
+	"math"
 
 	"github.com/c9s/bbgo/pkg/bbgo"
 	"github.com/c9s/bbgo/pkg/types"
+	"github.com/c9s/bbgo/pkg/util"
 )
 
 type Strategy struct {
-	symbol string
+	Symbol            string  `json:"symbol"`
+	Interval          string  `json:"interval"`
+	BaseQuantity      float64 `json:"baseQuantity"`
+	MaxAssetQuantity  float64 `json:"maxAssetQuantity"`
+	MinDropPercentage float64 `json:"minDropPercentage"`
 }
 
-func New(symbol string) *Strategy {
+func LoadFile(filepath string) (*Strategy, error) {
+	o, err := ioutil.ReadFile(filepath)
+	if err != nil {
+		return nil, err
+	}
+
+	var strategy Strategy
+	err = json.Unmarshal(o, &strategy)
+	return &strategy, err
+}
+
+func New(symbol string, interval string, baseQuantity float64) *Strategy {
 	return &Strategy{
-		symbol: symbol,
+		Symbol:            symbol,
+		Interval:          interval,
+		BaseQuantity:      baseQuantity,
+		MinDropPercentage: -0.08,
 	}
 }
 
+func (s *Strategy) SetMinDropPercentage(p float64) *Strategy {
+	s.MinDropPercentage = p
+	return s
+}
+
+func (s *Strategy) SetMaxAssetQuantity(q float64) *Strategy {
+	s.MaxAssetQuantity = q
+	return s
+}
+
 func (s *Strategy) Run(ctx context.Context, trader types.Trader, session *bbgo.ExchangeSession) error {
-	session.Subscribe(types.KLineChannel, s.symbol, types.SubscribeOptions{ Interval: "1h" })
+	session.Subscribe(types.KLineChannel, s.Symbol, types.SubscribeOptions{Interval: s.Interval})
 
 	session.Stream.OnKLineClosed(func(kline types.KLine) {
 		changePercentage := kline.GetChange() / kline.Open
 
-		// buy when price drops -10%
-		if changePercentage < -0.1 {
+		// buy when price drops -8%
+		if changePercentage < s.MinDropPercentage {
+			market, ok := session.Markets[s.Symbol]
+			if !ok {
+				return
+			}
+
+			baseBalance, ok := session.Account.Balance(market.BaseCurrency)
+			if ok {
+				// we hold too many
+				if util.NotZero(s.MaxAssetQuantity) && baseBalance.Available > s.MaxAssetQuantity {
+					return
+				}
+			}
+
 			trader.SubmitOrder(ctx, &types.SubmitOrder{
 				Symbol:   kline.Symbol,
 				Side:     types.SideTypeBuy,
 				Type:     types.OrderTypeMarket,
-				Quantity:       1.0,
+				Quantity: s.BaseQuantity * math.Abs(changePercentage),
 			})
 		}
 	})
 
 	return nil
 }
-
-
-
-
-

strategies/buyandhold/main.go

@@ -69,11 +69,12 @@ var rootCmd = &cobra.Command{
 		environ.AddExchange(sessionID, exchange).Subscribe(types.KLineChannel, symbol, types.SubscribeOptions{})
 
 		trader := bbgo.NewTrader(environ)
-		trader.AttachStrategy(sessionID, buyandhold.New(symbol))
-		trader.Run(ctx)
+		trader.AttachStrategy(sessionID, buyandhold.New(symbol, "1h", 0.1))
+		// trader.AttachCrossExchangeStrategy(...)
+		err = trader.Run(ctx)
 
 		cmdutil.WaitForSignal(ctx, syscall.SIGINT, syscall.SIGTERM)
-		return nil
+		return err
 	},
 }