import { createServerFn } from "@tanstack/react-start";
import { unreadNotifications } from "~/server/user-inbox";
import { enforceRateLimit, requestIp } from "~/server/limits";
import { z } from "zod";
import { viewerMiddleware } from "./middleware";
import { createSession, destroySession, loadUserByLogin } from "~/server/auth";
import { verifyPassword, verifyPasswordAgainstNobody } from "~/server/crypto";
import { createUser, githubOAuthEnabled, signupsEnabled } from "~/server/accounts";
import { badRequest } from "~/server/errors";
import { rehashIfStale, sendEmailVerification } from "~/server/account-security";
import { requiresSecondFactor, startPendingLogin } from "~/server/two-factor";
import { accountName, email, password } from "~/lib/validation";

export const getSession = createServerFn({ method: "GET" })
  .middleware([viewerMiddleware])
  .handler(async ({ context }) => {
    const unread = context.viewer ? await unreadNotifications(context.viewer.id) : 0;
    return { viewer: context.viewer, unreadNotifications: unread };
  });

export const getAuthOptions = createServerFn({ method: "GET" }).handler(async () => {
  return { signupsEnabled: signupsEnabled(), githubEnabled: githubOAuthEnabled() };
});

export const signUp = createServerFn({ method: "POST" })
  .validator(z.object({ username: accountName, email, password }))
  .handler(async ({ data }) => {
    await enforceRateLimit("AUTH_LIMITER", `signup:${requestIp()}`);
    const id = await createUser({
      name: data.username,
      email: data.email,
      password: data.password,
      githubId: null,
      displayName: null,
    });
    await createSession(id);
    await sendEmailVerification(id, data.email);
    return { ok: true };
  });

export const signIn = createServerFn({ method: "POST" })
  .validator(z.object({ login: z.string().trim().min(1), password: z.string().min(1) }))
  .handler(async ({ data }) => {
    const login = data.login.toLowerCase();
    await enforceRateLimit("AUTH_LIMITER", `login:${requestIp()}`);
    await enforceRateLimit("AUTH_LIMITER", `login:${login}:${requestIp()}`);
    // AUTH-A3: an account-level budget too, so spraying one account from many IPs still hits a ceiling.
    await enforceRateLimit("AUTH_LIMITER", `login:acct:${login}`);
    const user = await loadUserByLogin(data.login);
    // AUTH-A5: unknown logins burn the same PBKDF2 work as a wrong password, so timing does not enumerate accounts.
    const ok = user?.password_hash
      ? await verifyPassword(data.password, user.password_hash)
      : await verifyPasswordAgainstNobody(data.password);
    if (!user?.password_hash || !ok) {
      throw badRequest("Incorrect username or password");
    }
    await rehashIfStale(user.id, data.password, user.password_hash);
    if (await requiresSecondFactor(user.id)) {
      await startPendingLogin(user.id);
      return { ok: true, twoFactor: true };
    }
    await createSession(user.id);
    return { ok: true, twoFactor: false };
  });

export const signOut = createServerFn({ method: "POST" }).handler(async () => {
  await destroySession();
  return { ok: true };
});