Group C+ fixes

src/lib/validation.ts

@@ -30,23 +30,73 @@ export const SUPPORTED_COUNTRIES = ["CH", "DE", "AT", "FR", "IT", "LI"] as const
 export type SupportedCountry = (typeof SUPPORTED_COUNTRIES)[number];
 
 /**
- * Billing address — every field required at minimum non-empty length.
- * Postal code rules vary too much across DACH+ to enforce a single
- * regex usefully; we settle for "non-empty, ≤ 12 chars". Country is a
- * fixed enum to prevent free-text typos that break invoicing.
+ * Country-specific postal-code patterns. Bug 33: previously a postal
+ * code could be anything (e.g. "abc"), which broke invoicing.
+ *
+ * Patterns are deliberately conservative — they reject obviously wrong
+ * input but don't try to be exhaustive valid-range checkers (e.g. CH
+ * codes are 1000-9999 in practice but \d{4} accepts 0000; the post
+ * office will reject downstream if it matters). If a future country
+ * has multi-format codes (e.g. UK postcodes with the inner-outer
+ * structure), add it as a regex here rather than trying to fit
+ * every country into the same shape.
  */
-export const billingAddressSchema = z.object({
-  // Company line is structurally optional — personal accounts leave it
-  // empty by design (Bug 2). Server-side, the wizard's UI hides the
-  // field for personals; the schema just doesn't require it.
-  company: z.string().trim().max(100).optional().default(""),
-  street: z.string().trim().min(1, "required").max(200),
-  postalCode: z.string().trim().min(1, "required").max(12),
-  city: z.string().trim().min(1, "required").max(100),
-  country: z.enum(SUPPORTED_COUNTRIES, {
-    message: "Please choose a country from the list",
-  }),
-});
+const POSTAL_CODE_PATTERNS: Record<SupportedCountry, RegExp> = {
+  CH: /^\d{4}$/,
+  DE: /^\d{5}$/,
+  AT: /^\d{4}$/,
+  FR: /^\d{5}$/,
+  IT: /^\d{5}$/,
+  LI: /^\d{4}$/,
+};
+
+/**
+ * Postal-code expectation in human terms — used in error messages so
+ * the user gets a useful hint ("expected 4 digits") rather than just
+ * a regex failure. Keep in sync with POSTAL_CODE_PATTERNS.
+ */
+const POSTAL_CODE_HINTS: Record<SupportedCountry, string> = {
+  CH: "4 digits",
+  DE: "5 digits",
+  AT: "4 digits",
+  FR: "5 digits",
+  IT: "5 digits",
+  LI: "4 digits",
+};
+
+/**
+ * Billing address — every field required at minimum non-empty length.
+ * Postal code is validated against the chosen country (Bug 33). Country
+ * is a fixed enum to prevent free-text typos that break invoicing.
+ *
+ * `superRefine` is the right hook here because we need to look at two
+ * fields (country + postalCode) together. The error path is set on
+ * `postalCode` so the wizard renders the inline error under the right
+ * input rather than at the form root.
+ */
+export const billingAddressSchema = z
+  .object({
+    // Company line is structurally optional — personal accounts leave it
+    // empty by design (Bug 2). Server-side, the wizard's UI hides the
+    // field for personals; the schema just doesn't require it.
+    company: z.string().trim().max(100).optional().default(""),
+    street: z.string().trim().min(1, "required").max(200),
+    postalCode: z.string().trim().min(1, "required").max(12),
+    city: z.string().trim().min(1, "required").max(100),
+    country: z.enum(SUPPORTED_COUNTRIES, {
+      message: "Please choose a country from the list",
+    }),
+  })
+  .superRefine((data, ctx) => {
+    const pattern = POSTAL_CODE_PATTERNS[data.country];
+    if (!pattern.test(data.postalCode)) {
+      ctx.addIssue({
+        code: "custom",
+        path: ["postalCode"],
+        message: `Invalid postal code (expected ${POSTAL_CODE_HINTS[data.country]})`,
+      });
+    }
+  });
 
 export type BillingAddressInput = z.infer<typeof billingAddressSchema>;