refactor: add helper functions for subtotal, cart empty, and cart item count

pkg/tui/cart.go

@@ -28,7 +28,7 @@ func (m Model) updateCartViewport() Model {
 }
 
 func (m Model) generateCartContent() string {
-	if len(m.Cart) == 0 {
+	if m.IsCartEmpty() {
 		emptyStyle := m.theme.TextDim().
 			Align(lipgloss.Center).
 			Width(m.widthContent).
@@ -179,7 +179,7 @@ func (m Model) CartUpdate(msg tea.Msg) (Model, tea.Cmd) {
 			return m, m.syncCartItemCmd(coffeeID, newQty)
 		}
 	case "p", "enter":
-		if len(m.Cart) > 0 {
+		if !m.IsCartEmpty() {
 			return m.ShippingSwitch()
 		}
 	}

pkg/tui/confirmation.go

@@ -150,10 +150,8 @@ func (m Model) generateReviewContent() string {
 	}
 	view.WriteString("\n")
 
-	subtotal := 0
-	for _, item := range m.GetCartItemsSlice() {
-		subtotal += item.Coffee.Price * item.Quantity
-	}
+	subtotal := m.CalculateSubtotal()
+
 	view.WriteString(fmt.Sprintf("subtotal: %s\n", formatUSD(subtotal)))
 	view.WriteString(m.theme.TextAccent().Render(fmt.Sprintf("total:    %s", formatUSD(subtotal))) + "\n")
 	view.WriteString("\n")

pkg/tui/footer.go

@@ -135,7 +135,7 @@ func (m Model) BuildFooter() string {
 		}
 	} else if m.currentPage == cartPage {
 		// In cart view, show proceed option
-		if len(m.Cart) > 0 {
+		if !m.IsCartEmpty() {
 			footerText = fmt.Sprintf("%s %s    %s %s    %s %s    %s %s    %s %s    %s %s    %s %s    %s %s",
 				keybindStyle.Render("j/k"),
 				descStyle.Render("items"),

pkg/tui/header.go

@@ -8,12 +8,8 @@ import (
 
 func (m Model) BuildHeader() string {
 	// Calculate cart total and item count
-	total := 0
-	itemCount := 0
-	for _, item := range m.Cart {
-		total += item.Quantity * item.Coffee.Price
-		itemCount += item.Quantity
-	}
+	total := m.CalculateSubtotal()
+	itemCount := m.CartItemCount()
 
 	// Define colors
 	grayStyle := m.theme.TextBody()

pkg/tui/menu.go

@@ -32,12 +32,8 @@ func (m Model) BuildMenuView() string {
 
 	hint := base.Render("press esc to close")
 
-	itemCount := 0
-	total := 0
-	for _, item := range m.Cart {
-		total += item.Quantity * item.Coffee.Price
-		itemCount += item.Quantity
-	}
+	total := m.CalculateSubtotal()
+	itemCount := m.CartItemCount()
 
 	cartHint := base.Render(fmt.Sprintf("cart $%.2f [%d]", float64(total)/100, itemCount))
 

pkg/tui/model.go

@@ -755,6 +755,29 @@ func (m Model) GetCartItemsSlice() []*models.CartItem {
 	return items
 }
 
+// IsCartEmpty returns true when the cart has no items
+func (m Model) IsCartEmpty() bool {
+	return len(m.Cart) == 0
+}
+
+// CartItemCount returns the total number of items (sum of quanities) in the cart
+func (m Model) CartItemCount() int {
+	count := 0
+	for _, item := range m.Cart {
+		count += item.Quantity
+	}
+	return count
+}
+
+// CalculateSubtotal returns the cart subtotal in cents
+func (m Model) CalculateSubtotal() int {
+	subtotal := 0
+	for _, item := range m.Cart {
+		subtotal += item.Coffee.Price * item.Quantity
+	}
+	return subtotal
+}
+
 // NewModel creates a new model using the default renderer.
 func NewModel(username string) Model {
 	return newModelWithRenderer(username, lipgloss.DefaultRenderer())