import { jwtDecode } from "jwt-decode";

import type { AuthPayloadFragment, AuthUserFragment } from "#graphql/types";
import type { H3Event } from "h3";

/**
 * Handle user login by setting the session data with the provided authentication information.
 *
 * @param event The H3 event object.
 * @param payload The authentication payload containing user and token information.
 * @return A promise that resolves to true if the login was successful, or false if there was an error.
 */
export async function handleLogin(
  event: H3Event,
  { user, authToken, refreshToken }: AuthPayloadFragment,
) {
  if (!user || !authToken || !refreshToken) {
    return false;
  }

  await setUserSession(event, {
    user: getAuthUser(user),
    secure: { authToken, refreshToken },
    loggedInAt: new Date().toISOString(),
  });

  return true;
}

/**
 * Handle user logout by clearing the session data.
 *
 * @param event The H3 event object.
 * @returns A promise that resolves when the session has been cleared.
 */
export async function handleLogout(event: H3Event) {
  await clearUserSession(event);
}

/**
 * Convert the AuthUserFragment to a User object expected by nuxt-auth-utils
 *
 * @param user The AuthUserFragment containing user data from the GraphQL response
 * @returns A User object with the expected structure for nuxt-auth-utils, including an array of role names
 */
function getAuthUser(user: AuthUserFragment) {
  return {
    ...user,
    roles: user.roles.nodes.map(({ name }) => name) || [],
  };
}

/**
 * Retrieve the authentication token from the user's session, checking for expiration and handling token refresh if necessary.
 *
 * @param event The H3 event object, used to access the user's session data.
 * @returns A promise that resolves to the authentication token if it is valid, or undefined if there is no valid token or if the user is not authenticated.
 */
export async function getAuthToken(event: H3Event) {
  // Retrieve user session, return if none
  const session = await getUserSession(event);
  if (!session.secure) {
    return;
  }

  // Extract tokens and check expiration
  const decoded = jwtDecode<{ exp: number }>(session.secure.authToken);
  const isExpired = decoded.exp * 1000 < Date.now();
  if (isExpired) {
    // TOOD: Refresh token logic
  }

  return session.secure.authToken;
}