implement core foundation

go/internal/billing/config.go

@@ -0,0 +1,37 @@
+package billing
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Config struct {
+	SecretKey      string
+	WebhookSecret  string
+	PriceMonthlyID string
+	PriceAnnualID  string
+
+	SuccessURL string
+	CancelURL  string
+}
+
+func (c Config) Validate() error {
+	required := map[string]string{
+		"SecretKey":      c.SecretKey,
+		"WebhookSecret":  c.WebhookSecret,
+		"PriceMonthlyID": c.PriceMonthlyID,
+		"PriceAnnualID":  c.PriceAnnualID,
+		"SuccessURL":     c.SuccessURL,
+		"CancelURL":      c.CancelURL,
+	}
+	var missing []string
+	for name, value := range required {
+		if value == "" {
+			missing = append(missing, name)
+		}
+	}
+	if len(missing) > 0 {
+		return fmt.Errorf("billing config missing: %s", strings.Join(missing, ", "))
+	}
+	return nil
+}