4 files changed, 207 insertions, 0 deletions
diff --git a/frontend/app/routes/dashboard.tsx b/frontend/app/routes/dashboard.tsx
new file mode 100644
index 0000000..be274eb
--- /dev/null
+++ b/frontend/app/routes/dashboard.tsx
@@ -0,0 +1,22 @@
+import type { LoaderFunctionArgs } from "@remix-run/node";
+import { isAuthenticated } from "../services/auth.server";
+import { useLoaderData } from "@remix-run/react";
+
+export async function loader({ request }: LoaderFunctionArgs) {
+  return await isAuthenticated(request, {
+    failureRedirect: "/login",
+  });
+}
+
+export default function Dashboard() {
+  const user = useLoaderData<typeof loader>()!;
+
+  return (
+    <div>
+      <h1>
+        #{user.userId} {user.displayUsername} (@{user.username})
+      </h1>
+      {user.isAdmin && <p>Admin</p>}
+    </div>
+  );
+}
diff --git a/frontend/app/routes/login.tsx b/frontend/app/routes/login.tsx
new file mode 100644
index 0000000..cf5be14
--- /dev/null
+++ b/frontend/app/routes/login.tsx
@@ -0,0 +1,31 @@
+import type { ActionFunctionArgs, LoaderFunctionArgs } from "@remix-run/node";
+import { Form } from "@remix-run/react";
+import { authenticator } from "../services/auth.server";
+
+export async function loader({ request }: LoaderFunctionArgs) {
+  return await authenticator.isAuthenticated(request, {
+    successRedirect: "/dashboard",
+  });
+}
+
+export async function action({ request }: ActionFunctionArgs) {
+  return await authenticator.authenticate("default", request, {
+    successRedirect: "/dashboard",
+    failureRedirect: "/login",
+  });
+}
+
+export default function Login() {
+  return (
+    <Form method="post">
+      <input type="username" name="username" required />
+      <input
+        type="password"
+        name="password"
+        autoComplete="current-password"
+        required
+      />
+      <button>Log In</button>
+    </Form>
+  );
+}
diff --git a/frontend/app/services/auth.server.ts b/frontend/app/services/auth.server.ts
new file mode 100644
index 0000000..144a7cd
--- /dev/null
+++ b/frontend/app/services/auth.server.ts
@@ -0,0 +1,141 @@
+import { Authenticator } from "remix-auth";
+import { FormStrategy } from "remix-auth-form";
+import { sessionStorage } from "./session.server";
+import { jwtDecode } from "jwt-decode";
+import type { Session } from "@remix-run/server-runtime";
+
+export const authenticator = new Authenticator<string>(sessionStorage);
+
+async function login(username: string, password: string): Promise<string> {
+  const res = await fetch(`http://api-server/api/login`, {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({ username, password }),
+  });
+  if (!res.ok) {
+    throw new Error("Invalid username or password");
+  }
+  const user = await res.json();
+  return user.token;
+}
+
+authenticator.use(
+  new FormStrategy(async ({ form }) => {
+    const username = String(form.get("username"));
+    const password = String(form.get("password"));
+    return await login(username, password);
+  }),
+  "default",
+);
+
+type JwtPayload = {
+  user_id: number;
+  username: string;
+  display_username: string;
+  icon_path: string | null;
+  is_admin: boolean;
+};
+
+export type User = {
+  userId: number;
+  username: string;
+  displayUsername: string;
+  iconPath: string | null;
+  isAdmin: boolean;
+};
+
+export async function isAuthenticated(
+  request: Request | Session,
+  options?: {
+    successRedirect?: never;
+    failureRedirect?: never;
+    headers?: never;
+  },
+): Promise<User | null>;
+export async function isAuthenticated(
+  request: Request | Session,
+  options: {
+    successRedirect: string;
+    failureRedirect?: never;
+    headers?: HeadersInit;
+  },
+): Promise<null>;
+export async function isAuthenticated(
+  request: Request | Session,
+  options: {
+    successRedirect?: never;
+    failureRedirect: string;
+    headers?: HeadersInit;
+  },
+): Promise<User>;
+export async function isAuthenticated(
+  request: Request | Session,
+  options: {
+    successRedirect: string;
+    failureRedirect: string;
+    headers?: HeadersInit;
+  },
+): Promise<null>;
+export async function isAuthenticated(
+  request: Request | Session,
+  options:
+    | {
+        successRedirect?: never;
+        failureRedirect?: never;
+        headers?: never;
+      }
+    | {
+        successRedirect: string;
+        failureRedirect?: never;
+        headers?: HeadersInit;
+      }
+    | {
+        successRedirect?: never;
+        failureRedirect: string;
+        headers?: HeadersInit;
+      }
+    | {
+        successRedirect: string;
+        failureRedirect: string;
+        headers?: HeadersInit;
+      } = {},
+): Promise<User | null> {
+  let jwt;
+
+  // This function's signature should be compatible with `authenticator.isAuthenticated` but TypeScript does not infer it correctly.
+  const { successRedirect, failureRedirect, headers } = options;
+  if (successRedirect && failureRedirect) {
+    jwt = await authenticator.isAuthenticated(request, {
+      successRedirect,
+      failureRedirect,
+      headers,
+    });
+  } else if (!successRedirect && failureRedirect) {
+    jwt = await authenticator.isAuthenticated(request, {
+      failureRedirect,
+      headers,
+    });
+  } else if (successRedirect && !failureRedirect) {
+    jwt = await authenticator.isAuthenticated(request, {
+      successRedirect,
+      headers,
+    });
+  } else {
+    jwt = await authenticator.isAuthenticated(request);
+  }
+
+  if (!jwt) {
+    return null;
+  }
+  // TODO: runtime type check
+  const payload = jwtDecode<JwtPayload>(jwt);
+  return {
+    userId: payload.user_id,
+    username: payload.username,
+    displayUsername: payload.display_username,
+    iconPath: payload.icon_path,
+    isAdmin: payload.is_admin,
+  };
+}
diff --git a/frontend/app/services/session.server.ts b/frontend/app/services/session.server.ts
new file mode 100644
index 0000000..2000853
--- /dev/null
+++ b/frontend/app/services/session.server.ts
@@ -0,0 +1,13 @@
+import { createCookieSessionStorage } from "@remix-run/node";
+
+export const sessionStorage = createCookieSessionStorage({
+  cookie: {
+    name: "albatross_session",
+    sameSite: "lax",
+    path: "/",
+    httpOnly: true,
+    secrets: ["TODO"],
+    // secure: process.env.NODE_ENV === "production",
+    secure: false, // TODO
+  },
+});