fix: currency conversion

cmd/add.go

@@ -138,25 +138,6 @@ func runAdd(cmd *cobra.Command, args []string) error {
 		bill.PaymentModeID = methodID
 	}
 
-	// Resolve optional currency
-	if convertTo != "" {
-		currencyID, err := cache.ResolveCurrency(project, convertTo)
-		if err != nil {
-			return fmt.Errorf("resolving currency: %w", err)
-		}
-		bill.OriginalCurrencyID = currencyID
-	}
-
-	// Add optional comment
-	if comment != "" {
-		bill.Comment = comment
-	}
-
-	// Create the bill
-	if err := client.CreateBill(ProjectID, bill); err != nil {
-		return fmt.Errorf("creating bill: %w", err)
-	}
-
 	// Fetch user info for locale-aware formatting
 	locale := "en_US"
 	userInfo, ok := cache.LoadUserInfo()
@@ -172,7 +153,29 @@ func runAdd(cmd *cobra.Command, args []string) error {
 		locale = userInfo.Language
 	}
 
+	// Resolve optional currency and convert amount
+	if convertTo != "" {
+		currency, err := cache.ResolveCurrency(project, convertTo)
+		if err != nil {
+			return fmt.Errorf("resolving currency: %w", err)
+		}
+		bill.OriginalCurrencyID = currency.ID
+		bill.Amount = amount * currency.ExchangeRate
+		origFormatter := format.NewAmountFormatter(locale, currency.Name)
+		bill.What = fmt.Sprintf("%s (%s)", expenseName, origFormatter.Format(amount))
+	}
+
+	// Add optional comment
+	if comment != "" {
+		bill.Comment = comment
+	}
+
+	// Create the bill
+	if err := client.CreateBill(ProjectID, bill); err != nil {
+		return fmt.Errorf("creating bill: %w", err)
+	}
+
 	formatter := format.NewAmountFormatter(locale, project.CurrencyName)
-	_, _ = fmt.Fprintf(cmd.OutOrStdout(), "Successfully added expense: %s (%s)\n", expenseName, formatter.Format(amount))
+	_, _ = fmt.Fprintf(cmd.OutOrStdout(), "Successfully added expense: %s (%s)\n", expenseName, formatter.Format(bill.Amount))
 	return nil
 }

cmd/add_test.go

@@ -233,7 +233,7 @@ func TestAddCommandWithAllFlags(t *testing.T) {
 			{ID: 3, Name: "Credit Card"},
 		},
 		Currencies: []api.Currency{
-			{ID: 2, Name: "€"},
+			{ID: 2, Name: "€", ExchangeRate: 0.85},
 		},
 	}
 
@@ -288,11 +288,11 @@ func TestAddCommandWithAllFlags(t *testing.T) {
 	}
 
 	// Verify bill data
-	if receivedBill["what"] != "Dinner" {
+	if receivedBill["what"] != "Dinner (€ 45.00)" {
 		t.Errorf("Wrong what: %s", receivedBill["what"])
 	}
-	if receivedBill["amount"] != "45.00" {
-		t.Errorf("Wrong amount: %s", receivedBill["amount"])
+	if receivedBill["amount"] != "38.25" { // 45.00 * 0.85 exchange rate
+		t.Errorf("Wrong amount: got %s, want 38.25 (45.00 * 0.85)", receivedBill["amount"])
 	}
 	if receivedBill["payer"] != "2" { // Alice's ID
 		t.Errorf("Wrong payer: %s", receivedBill["payer"])

internal/cache/cache.go

@@ -346,33 +346,33 @@ func ResolvePaymentMode(project *api.Project, nameOrID string) (int, error) {
 	return 0, fmt.Errorf("payment mode not found: %s", nameOrID)
 }
 
-// ResolveCurrency finds a currency by name (case-insensitive), ID, or currency code symbol and returns the ID
-func ResolveCurrency(project *api.Project, nameOrID string) (int, error) {
+// ResolveCurrency finds a currency by name (case-insensitive), ID, or currency code symbol and returns the currency
+func ResolveCurrency(project *api.Project, nameOrID string) (*api.Currency, error) {
 	// Try parsing as ID first
 	if id, err := strconv.Atoi(nameOrID); err == nil {
-		for _, cur := range project.Currencies {
-			if cur.ID == id {
-				return id, nil
+		for i := range project.Currencies {
+			if project.Currencies[i].ID == id {
+				return &project.Currencies[i], nil
 			}
 		}
 	}
 
 	// Try matching by name (case-insensitive)
 	lowerName := strings.ToLower(nameOrID)
-	for _, cur := range project.Currencies {
-		if strings.ToLower(cur.Name) == lowerName {
-			return cur.ID, nil
+	for i := range project.Currencies {
+		if strings.ToLower(project.Currencies[i].Name) == lowerName {
+			return &project.Currencies[i], nil
 		}
 	}
 
 	// Try matching by currency code symbol (e.g., "usd" -> "$")
 	if symbol, ok := currencyCodeToSymbol[lowerName]; ok {
-		for _, cur := range project.Currencies {
-			if strings.Contains(cur.Name, symbol) {
-				return cur.ID, nil
+		for i := range project.Currencies {
+			if strings.Contains(project.Currencies[i].Name, symbol) {
+				return &project.Currencies[i], nil
 			}
 		}
 	}
 
-	return 0, fmt.Errorf("currency not found: %s", nameOrID)
+	return nil, fmt.Errorf("currency not found: %s", nameOrID)
 }

internal/cache/cache_test.go

@@ -164,13 +164,13 @@ func TestResolveCurrency(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			gotID, err := ResolveCurrency(project, tt.nameOrID)
+			got, err := ResolveCurrency(project, tt.nameOrID)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("ResolveCurrency() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
-			if gotID != tt.wantID {
-				t.Errorf("ResolveCurrency() = %v, want %v", gotID, tt.wantID)
+			if err == nil && got.ID != tt.wantID {
+				t.Errorf("ResolveCurrency() ID = %v, want %v", got.ID, tt.wantID)
 			}
 		})
 	}