elysium/apps/api/src/middleware/auth.ts

/**
 * @file Authentication middleware for validating JWT tokens.
 * @copyright nhcarrigan
 * @license Naomi's Public License
 * @author Naomi Carrigan
 */

import { verifyToken } from "../services/jwt.js";
import type { HonoEnvironment } from "../types/hono.js";
import type { MiddlewareHandler } from "hono";

/**
 * Validates the Authorization Bearer token on each request and attaches the discordId to context.
 * @param context - The Hono context object.
 * @param next - The next middleware handler.
 * @returns A JSON error response if authentication fails, otherwise calls next.
 */
export const authMiddleware: MiddlewareHandler<HonoEnvironment> = async(
  context,
  next,
) => {
  const authorization = context.req.header("Authorization");

  if (authorization?.startsWith("Bearer ") !== true) {
    return context.json(
      { error: "Missing or invalid Authorization header" },
      401,
    );
  }

  const token = authorization.slice(7);

  try {
    const payload = verifyToken(token);
    context.set("discordId", payload.discordId);
  } catch {
    return context.json({ error: "Invalid or expired token" }, 401);
  }

  // eslint-disable-next-line @typescript-eslint/no-confusing-void-expression -- Need the consistent return!
  return await next();
};