auth.js

import NextAuth from "next-auth";
import Credentials from "next-auth/providers/credentials";
import Google from "next-auth/providers/google";
import { connectDB } from "@/lib/mongodb";
import User from "@/models/User";
import bcrypt from "bcryptjs";

function generateReferralCode(name) {
  const cleanName = name.replace(/[^a-zA-Z]/g, "").toUpperCase().slice(0, 5);
  const randomNum = Math.floor(1000 + Math.random() * 9000);
  return `${cleanName}${randomNum}`;
}

export const { handlers, signIn, signOut, auth } = NextAuth({
  trustHost: true,
  providers: [
    Google({
      clientId: process.env.GOOGLE_CLIENT_ID,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET,
    }),
    Credentials({
      credentials: {
        email: { label: "Email", type: "email" },
        password: { label: "Password", type: "password" },
      },
      async authorize(credentials) {
        await connectDB();
        const user = await User.findOne({ email: credentials.email });
        if (!user) throw new Error("No user found");
        const isValid = await bcrypt.compare(credentials.password, user.password);
        if (!isValid) throw new Error("Invalid password");
        return { id: user._id.toString(), name: user.name, email: user.email };
      },
    }),
  ],
  callbacks: {
    async signIn({ user, account }) {
      if (account?.provider === "google") {
        await connectDB();
        const existing = await User.findOne({ email: user.email });
        if (!existing) {
          // Create new user from Google login
          await User.create({
            name: user.name,
            email: user.email,
            password: null,
            referralCode: generateReferralCode(user.name),
            bonusGenerations: 0,
          });
        }
        return true;
      }
      return true;
    },
  },
  pages: {
    signIn: "/login",
  },
  session: { strategy: "jwt" },
  secret: process.env.NEXTAUTH_SECRET,
});