save: @auth/core implementation in fresh framework

README.md

how to use it?

To resolve dependencies defined by @auth/core First you need to modify ./import_map.json and add this scope

{
  "imports": {...},
  "scopes": {
    ...
    "https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/": {
      "@panva/hkdf": "https://deno.land/x/hkdf@v1.0.4/index.ts",
      "oauth4webapi": "https://deno.land/x/oauth4webapi@v2.2.0/mod.ts",
      "cookie": "https://esm.sh/v113/cookie@0.5.0"
    },
  }
}

freshauth.ts

// see the original implementation: https://github.com/nextauthjs/next-auth/blob/main/packages/frameworks-solid-start/src/index.ts
// Note: Any dependencies by @auth/core is scoped in import_map.json
import { Handler, Status } from "$fresh/server.ts";
// @deno-types="https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/index.d.ts"
import {
  Auth,
  AuthConfig,
} from "https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/index.js";
// @deno-types="https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/types.d.ts"
import {
  AuthAction,
  Session,
} from "https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/types.js";
// @deno-types="https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/providers/github.d.ts"
export { default as GitHubProvider } from "https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/providers/github.js";

export type { AuthAction };

// custom role
export type Role = "admin" | "user";

// a custom declaration
declare module "https://cdn.jsdelivr.net/npm/@auth/core@0.5.1/types.js" {
  interface User {
    role?: Role | null;
  }
  interface Session {
    user: {
      role?: Role | null;
    } & DefaultUser;
  }
}

export interface FreshAuthConfig extends AuthConfig {
  /**
   * Defines the base path for the auth routes.
   * @default '/api/auth'
   */
  prefix?: string;
}

const actions: AuthAction[] = [
  "providers",
  "session",
  "csrf",
  "signin",
  "signout",
  "callback",
  "verify-request",
  "error",
];

export function FreshAuth(config: FreshAuthConfig): Handler {
  const { prefix = "/api/auth", ...authOptions } = config;
  authOptions.secret ??= Deno.env.get("AUTH_SECRET");
  authOptions.trustHost ??= !!(
    Deno.env.get("AUTH_TRUST_HOST") ?? Deno.env.get("DENO_DEPLOYMENT_ID")
  );
  return async (request: Request, _ctx) => {
    if (!["GET", "POST"].includes(request.method))
      return new Response("Invalid method", { status: Status.NotImplemented });
    const url = new URL(request.url);
    const action = url.pathname
      .slice(prefix.length + 1)
      .split("/")[0] as AuthAction;
    if (!actions.includes(action) || !url.pathname.startsWith(prefix + "/")) {
      return new Response("Not Found", { status: Status.NotFound });
    }
    const response = await Auth(request, authOptions);
    // const resp = response.clone();
    // console.log(await resp.text());
    return response;
  };
}

export type GetSessionResult = Promise<Session | null>;

export async function getSession(
  req: Request,
  options: FreshAuthConfig
): GetSessionResult {
  options.secret ??= Deno.env.get("AUTH_SECRET");
  options.trustHost ??= true;
  const { prefix = "/api/auth" } = options;

  const url = new URL(`${prefix}/session`, req.url);
  const response = await Auth(
    new Request(url, { headers: req.headers }),
    options
  );

  const { status = Status.OK } = response;

  const data = await response.json();

  if (!data || !Object.keys(data).length) return null;
  if (status === Status.OK) return data;
  throw new Error(data.message);
}