fix(coin): accept symbol-first trades

internal/modules/coin/handlers.go

@@ -70,16 +70,17 @@ func (s *state) handleBuy(ctx context.Context, b *bot.Bot, update *models.Update
 	}
 	args := argsAfterCommand(update.Message.Text)
 	if len(args) != 2 {
-		return chathelper.Reply(ctx, b, update.Message, "Usage: /coin_buy <usd_amount> <COIN>\nExample: /coin_buy 100 BTC")
+		return chathelper.Reply(ctx, b, update.Message, "Usage: /coin_buy <COIN> <usd_amount>\nExample: /coin_buy BTC 10")
 	}
-	amount, ok := parsePositiveFinite(args[0])
-	if !ok || !isSafeUSD(amount) {
+	parsed, err := parseCoinValueArgs(args, isSafeUSD, errInvalidUSDAmount)
+	if errors.Is(err, errInvalidUSDAmount) {
 		return chathelper.Reply(ctx, b, update.Message, "USD amount must be a positive finite number within the supported range.")
 	}
-	coin, err := ResolveCoinSymbol(args[1])
 	if err != nil {
 		return s.replyPriceError(ctx, b, update, err)
 	}
+	coin := parsed.coin
+	amount := parsed.value
 	price, err := s.prices.FetchUSD(ctx, coin)
 	if err != nil {
 		return s.replyPriceError(ctx, b, update, err)
@@ -120,16 +121,17 @@ func (s *state) handleSell(ctx context.Context, b *bot.Bot, update *models.Updat
 	}
 	args := argsAfterCommand(update.Message.Text)
 	if len(args) != 2 {
-		return chathelper.Reply(ctx, b, update.Message, "Usage: /coin_sell <qty> <COIN>\nExample: /coin_sell 0.01 BTC")
+		return chathelper.Reply(ctx, b, update.Message, "Usage: /coin_sell <COIN> <qty>\nExample: /coin_sell BTC 0.01")
 	}
-	qty, ok := parsePositiveFinite(args[0])
-	if !ok {
+	parsed, err := parseCoinValueArgs(args, isPositiveFinite, errInvalidQuantity)
+	if errors.Is(err, errInvalidQuantity) {
 		return chathelper.Reply(ctx, b, update.Message, "Quantity must be a positive finite number.")
 	}
-	coin, err := ResolveCoinSymbol(args[1])
 	if err != nil {
 		return s.replyPriceError(ctx, b, update, err)
 	}
+	coin := parsed.coin
+	qty := parsed.value
 	price, err := s.prices.FetchUSD(ctx, coin)
 	if err != nil {
 		return s.replyPriceError(ctx, b, update, err)

internal/modules/coin/handlers_order_test.go

@@ -0,0 +1,45 @@
+package coin
+
+import (
+	"context"
+	"testing"
+
+	"github.com/tiennm99/miti99bot/internal/testutil"
+)
+
+func TestHandleBuyAcceptsCoinFirstOrder(t *testing.T) {
+	ctx := context.Background()
+	s := newTestState(map[string]CoinPrice{"BTC": {USD: 50000, Source: "Binance"}}, nil)
+	rb := testutil.NewRecordingBot(t)
+	_ = s.handleTopup(ctx, rb.Bot, testutil.NewPrivateMessage(7, "/coin_topup 1000"))
+	rb.Reset()
+
+	if err := s.handleBuy(ctx, rb.Bot, testutil.NewPrivateMessage(7, "/coin_buy BTC 10")); err != nil {
+		t.Fatalf("handleBuy: %v", err)
+	}
+
+	rb.AssertSentText(t, "Bought 0.0002 BTC")
+	p, _ := LoadPortfolio(ctx, s.kv, 7, 999)
+	if p.USD != 990 || p.Assets["BTC"] != 0.0002 {
+		t.Fatalf("after coin-first buy = %+v", p)
+	}
+}
+
+func TestHandleSellAcceptsCoinFirstOrder(t *testing.T) {
+	ctx := context.Background()
+	s := newTestState(map[string]CoinPrice{"BTC": {USD: 50000, Source: "Binance"}}, nil)
+	rb := testutil.NewRecordingBot(t)
+	_ = s.handleTopup(ctx, rb.Bot, testutil.NewPrivateMessage(7, "/coin_topup 1000"))
+	_ = s.handleBuy(ctx, rb.Bot, testutil.NewPrivateMessage(7, "/coin_buy 500 BTC"))
+	rb.Reset()
+
+	if err := s.handleSell(ctx, rb.Bot, testutil.NewPrivateMessage(7, "/coin_sell BTC 0.01")); err != nil {
+		t.Fatalf("handleSell: %v", err)
+	}
+
+	rb.AssertSentText(t, "Sold 0.01 BTC")
+	p, _ := LoadPortfolio(ctx, s.kv, 7, 999)
+	if p.USD != 1000 || len(p.Assets) != 0 {
+		t.Fatalf("after coin-first sell = %+v", p)
+	}
+}

internal/modules/coin/trade_args.go

@@ -0,0 +1,38 @@
+package coin
+
+import "errors"
+
+var (
+	errInvalidUSDAmount = errors.New("coin: invalid USD amount")
+	errInvalidQuantity  = errors.New("coin: invalid quantity")
+)
+
+type coinValueArgs struct {
+	coin  CoinSymbol
+	value float64
+}
+
+func parseCoinValueArgs(args []string, validValue func(float64) bool, invalidValueErr error) (coinValueArgs, error) {
+	if len(args) != 2 {
+		return coinValueArgs{}, invalidValueErr
+	}
+	if coin, err := ResolveCoinSymbol(args[0]); err == nil {
+		value, ok := parsePositiveFinite(args[1])
+		if !ok || !validValue(value) {
+			return coinValueArgs{}, invalidValueErr
+		}
+		return coinValueArgs{coin: coin, value: value}, nil
+	}
+	value, ok := parsePositiveFinite(args[0])
+	if !ok || !validValue(value) {
+		if _, secondOK := parsePositiveFinite(args[1]); secondOK {
+			return coinValueArgs{}, ErrUnsupportedCoin
+		}
+		return coinValueArgs{}, invalidValueErr
+	}
+	coin, err := ResolveCoinSymbol(args[1])
+	if err != nil {
+		return coinValueArgs{}, err
+	}
+	return coinValueArgs{coin: coin, value: value}, nil
+}