refactor: enforce frontend view model boundaries

src/features/auth/model/auth.schema.ts

@@ -0,0 +1,61 @@
+import { z } from "zod";
+
+import { validationMessage } from "@/shared/i18n";
+
+const EMAIL_PART_COUNT = 2;
+
+const ASCII_SPACE = 32;
+const ASCII_DELETE = 127;
+const MAX_EMAIL_LENGTH = 254;
+const MIN_PASSWORD_BYTES = 12;
+const MAX_PASSWORD_BYTES = 72;
+
+function isEmailCharacterInvalid(character: string): boolean {
+	const codePoint = character.codePointAt(0);
+
+	return (
+		/\s/.test(character)
+		|| (codePoint !== undefined && codePoint < ASCII_SPACE)
+		|| codePoint === ASCII_DELETE
+	);
+}
+
+const email = z
+	.string()
+	.trim()
+	.toLowerCase()
+	.max(MAX_EMAIL_LENGTH)
+	.refine(
+		value =>
+			value.split("@").length === EMAIL_PART_COUNT
+			&& value.split("@").every(Boolean)
+			&& value.split("").every(element => !isEmailCharacterInvalid(element)),
+		{ error: validationMessage("auth.validation.invalidEmail") },
+	);
+
+const password = z
+	.string()
+	.refine(
+		value =>
+			new TextEncoder().encode(value).length >= MIN_PASSWORD_BYTES
+				&& new TextEncoder().encode(value).length <= MAX_PASSWORD_BYTES,
+		{ error: validationMessage("auth.validation.invalidPasswordLength") },
+	);
+
+const loginSchema = z.object({
+	email,
+	password,
+	passwordConfirmation: z.string().optional(),
+});
+
+const registerSchema = loginSchema.refine(
+	value => value.password === value.passwordConfirmation,
+	{
+		error: validationMessage("auth.validation.passwordsDoNotMatch"),
+		path: ["passwordConfirmation"],
+	},
+);
+
+type AuthFormValues = z.input<typeof loginSchema>;
+
+export { type AuthFormValues, loginSchema, registerSchema };