/**
 * Checks the JSON bodies that the federation routes (`routes/federation.ts`,
 * `routes/oauth.ts`) receive before they read them. They check the shapes
 * only: whether an instance answers, or a code or an invite works, is the
 * services' check.
 *
 * @module
 */

import {
  type AuthorizeRequest,
  type FederationLoginRequest,
  type FederationSessionRequest,
  isPeerStatus,
  type SetPeerRequest,
} from "../../shared/federation.ts";

/** Returns whether `obj` is an object whose `keys` are all strings. */
function hasStrings(obj: unknown, keys: string[]): boolean {
  return !!obj && typeof obj === "object" &&
    keys.every((k) => typeof (obj as Record<string, unknown>)[k] === "string");
}

/** Checks whether `obj` is a {@link FederationLoginRequest}. */
export function isFederationLoginRequest(
  obj: unknown,
): obj is FederationLoginRequest {
  if (!hasStrings(obj, ["instance"])) return false;
  const invite = (obj as Record<string, unknown>).inviteToken;
  return invite === undefined || typeof invite === "string";
}

/** Checks whether `obj` is a {@link FederationSessionRequest}. */
export function isFederationSessionRequest(
  obj: unknown,
): obj is FederationSessionRequest {
  return hasStrings(obj, ["code", "state"]);
}

/** Checks whether `obj` is an {@link AuthorizeRequest}. */
export function isAuthorizeRequest(obj: unknown): obj is AuthorizeRequest {
  return hasStrings(obj, [
    "clientId",
    "redirectUri",
    "state",
    "codeChallenge",
    "codeChallengeMethod",
    "nonce",
  ]);
}

/** Checks whether `obj` is a {@link SetPeerRequest}. */
export function isSetPeerRequest(obj: unknown): obj is SetPeerRequest {
  return hasStrings(obj, ["instance"]) &&
    isPeerStatus((obj as Record<string, unknown>).status);
}