Ekklesia/packages/contracts/src/authorization.ts

import { z } from "zod";
import { permissionIdSchema } from "./identifiers.js";
import type { EkklesiaUserId } from "./identity.js";
import { parseEkklesiaUserId } from "./identity.js";

/**
 * Opaque at the type level via Zod's nominal `.brand()`, exactly like `EkklesiaUserId` and
 * `PermissionId`: a plain `string` is not assignable to `GrantId` without passing through
 * `parseGrantId`/`safeParseGrantId`. Ekklesia does not assume any particular format; Core's
 * Postgres-backed store happens to generate a UUID, but callers must treat the value as opaque.
 */
export const grantIdSchema = z.string().trim().min(1).max(128).brand<"GrantId">();

export type GrantId = z.infer<typeof grantIdSchema>;

export function parseGrantId(input: unknown): GrantId {
  return grantIdSchema.parse(input);
}

export function safeParseGrantId(input: unknown): z.ZodSafeParseResult<GrantId> {
  return grantIdSchema.safeParse(input);
}

/**
 * A generic, Core-opaque resource scope narrowing a grant or an authorization check to one
 * resource (for example a specific calendar event or media item). Core never interprets the
 * value beyond exact string equality — the owning module defines what a scope string means, if
 * anything. Not branded: unlike a permission or a grant, a scope carries no identity of its own
 * within Core; it is simply an opaque comparison key.
 */
export const authorizationScopeSchema = z.string().trim().min(1).max(256);

export type AuthorizationScope = z.infer<typeof authorizationScopeSchema>;

export function parseAuthorizationScope(input: unknown): AuthorizationScope {
  return authorizationScopeSchema.parse(input);
}

export function safeParseAuthorizationScope(
  input: unknown,
): z.ZodSafeParseResult<AuthorizationScope> {
  return authorizationScopeSchema.safeParse(input);
}

/**
 * Every permission declaration has exactly one baseline. `public` allows any principal, anonymous
 * or authenticated. `authenticated` requires a valid authenticated principal and nothing more.
 * `restricted` requires an active matching grant or platform-owner authority — baseline alone
 * never satisfies it.
 */
export const permissionBaselineSchema = z.enum(["public", "authenticated", "restricted"]);

export type PermissionBaseline = z.infer<typeof permissionBaselineSchema>;

/**
 * The one authoritative shape of a *registered* permission declaration — what both Core's
 * authorization registry (`core/src/authorization/permissions.ts`) and a module manifest's
 * `permissions` array parse into, so a permission a module declares and a permission Core's
 * registry enforces are provably the same structure, never two independently maintained
 * interfaces that could quietly drift apart. `.strict()` rejects any property beyond these three —
 * there is no room for a module or a future caller to smuggle extra, unvalidated metadata into a
 * declaration Core treats as trusted.
 *
 * This schema says nothing about *registration*: parsing a value into a `PermissionDeclaration`
 * only proves it is shaped correctly, not that any registry has accepted it. Registration remains
 * exclusively `PermissionRegistry`'s responsibility (`core/src/authorization/permissions.ts`) —
 * built by composing exactly the declarations a trusted caller supplies, Core's own plus every
 * discovered module's.
 */
export const permissionDeclarationSchema = z
  .object({
    id: permissionIdSchema,
    baseline: permissionBaselineSchema,
    /** Operator/audit-facing text only. Authorization never reads, parses, or otherwise
     * interprets this value — changing it can never change what a permission allows. */
    description: z.string().trim().min(1).max(240),
  })
  .strict();

export type PermissionDeclarationInput = z.input<typeof permissionDeclarationSchema>;
export type PermissionDeclaration = z.output<typeof permissionDeclarationSchema>;

export function parsePermissionDeclaration(input: unknown): PermissionDeclaration {
  return permissionDeclarationSchema.parse(input);
}

export function safeParsePermissionDeclaration(
  input: unknown,
): z.ZodSafeParseResult<PermissionDeclaration> {
  return permissionDeclarationSchema.safeParse(input);
}

/**
 * Distinguishes a grant an operator/system created directly (`explicit`) from one a module
 * created as a side effect of its own business operation, attributed to some source the module
 * understands (`relationship`) — for example adding a person to a volunteer roster. Core never
 * interprets which relationship produced the grant; it only records the distinction and an
 * opaque source reference for audit purposes.
 */
export const grantSourceKindSchema = z.enum(["explicit", "relationship"]);

export type GrantSourceKind = z.infer<typeof grantSourceKindSchema>;

/** A Core-opaque reference to whatever produced a `relationship` grant (or, optionally, extra
 * context for an `explicit` one) — for example a module-defined identifier. Never interpreted by
 * Core, never a foreign key into another module's tables. */
export const grantSourceRefSchema = z.string().trim().min(1).max(256);

export type GrantSourceRef = z.infer<typeof grantSourceRefSchema>;

const authorizationActorTypeSchema = z.enum(["user", "system"]);

export type AuthorizationActorType = z.infer<typeof authorizationActorTypeSchema>;

export interface AuthorizationUserActor {
  readonly type: "user";
  readonly userId: EkklesiaUserId;
}

export interface AuthorizationSystemActor {
  readonly type: "system";
}

/**
 * Who performed a security-relevant authorization mutation (a grant or platform-owner change).
 * Mirrors `EkklesiaPrincipal`'s discriminated-union style. `system` covers Core-internal or
 * automated actions with no specific human actor (for example a future bootstrap command run by
 * an operator with no prior Ekklesia identity); it never means "unauthenticated" or "anonymous
 * caller" — every mutating call site chooses this deliberately.
 */
export type AuthorizationActor = AuthorizationUserActor | AuthorizationSystemActor;

export const SYSTEM_ACTOR: AuthorizationSystemActor = Object.freeze({ type: "system" });

export function createUserActor(userId: unknown): AuthorizationUserActor {
  return Object.freeze({ type: "user", userId: parseEkklesiaUserId(userId) });
}

export function isUserActor(actor: AuthorizationActor): actor is AuthorizationUserActor {
  return actor.type === "user";
}

/**
 * The only public result of an authorization check. Deliberately minimal and frozen: it never
 * carries a reason, a matched grant, a permission echo, or any other detail a caller could use to
 * infer another user's grants or Core's internal evaluation path. `AUTHORIZATION_ALLOWED` and
 * `AUTHORIZATION_DENIED` are the only two values ever produced.
 */
export interface AuthorizationDecision {
  readonly allowed: boolean;
}

export const AUTHORIZATION_ALLOWED: AuthorizationDecision = Object.freeze({ allowed: true });
export const AUTHORIZATION_DENIED: AuthorizationDecision = Object.freeze({ allowed: false });

export function isAuthorizationAllowed(decision: AuthorizationDecision): boolean {
  return decision.allowed;
}