import { z } from "zod";

/**
 * Opaque at the type level via Zod's nominal `.brand()`: a plain `string` is not assignable to
 * `EkklesiaUserId` without passing through `parseEkklesiaUserId`/`safeParseEkklesiaUserId`. The
 * brand exists only in the type system — it adds no runtime tag, wrapper, or field, so a value
 * still serializes (JSON.stringify, string concatenation, equality) as a plain opaque string.
 * Ekklesia does not assume any particular format (in particular, not UUID): Phase 4A's identity
 * schema stores Better Auth's default application-generated id, an opaque base62-ish string, not
 * a database-generated UUID. Only the constraints Ekklesia itself owns are validated: non-empty
 * after trimming, and a generous upper bound against unreasonably large values.
 */
export const ekklesiaUserIdSchema = z.string().trim().min(1).max(128).brand<"EkklesiaUserId">();

export type EkklesiaUserId = z.infer<typeof ekklesiaUserIdSchema>;

export function parseEkklesiaUserId(input: unknown): EkklesiaUserId {
  return ekklesiaUserIdSchema.parse(input);
}

export function safeParseEkklesiaUserId(input: unknown): z.ZodSafeParseResult<EkklesiaUserId> {
  return ekklesiaUserIdSchema.safeParse(input);
}

export interface EkklesiaAnonymousPrincipal {
  readonly kind: "anonymous";
}

export interface EkklesiaAuthenticatedPrincipal {
  readonly kind: "authenticated";
  readonly userId: EkklesiaUserId;
}

export type EkklesiaPrincipal = EkklesiaAnonymousPrincipal | EkklesiaAuthenticatedPrincipal;

export const ANONYMOUS_PRINCIPAL: EkklesiaAnonymousPrincipal = Object.freeze({
  kind: "anonymous",
});

export function createAuthenticatedPrincipal(userId: unknown): EkklesiaAuthenticatedPrincipal {
  return Object.freeze({
    kind: "authenticated",
    userId: parseEkklesiaUserId(userId),
  });
}

export function isAnonymousPrincipal(
  principal: EkklesiaPrincipal,
): principal is EkklesiaAnonymousPrincipal {
  return principal.kind === "anonymous";
}

export function isAuthenticatedPrincipal(
  principal: EkklesiaPrincipal,
): principal is EkklesiaAuthenticatedPrincipal {
  return principal.kind === "authenticated";
}