import NextAuth from "next-auth";
import Credentials from "next-auth/providers/credentials";
import Discord from "next-auth/providers/discord";
import Google from "next-auth/providers/google";
import { LaravelEncrypter } from "@/lib/auth/laravel-encrypter";
import { checkLogin } from "@/lib/auth/password";
import { verifyTotp } from "@/lib/auth/totp";
import { prisma } from "@/lib/prisma";
import { env } from "@/env";

export const { handlers, signIn, signOut, auth } = NextAuth({
  trustHost: true,
  session: { strategy: "jwt", maxAge: 24 * 60 * 60 },
  pages: { signIn: "/login" },
  providers: [
    Credentials({
      credentials: {
        username: { label: "Username", type: "text" },
        password: { label: "Password", type: "password" },
        code: { label: "2FA code", type: "text" },
      },
      authorize: async (credentials) => {
        const username = String(credentials?.username ?? "").trim();
        const password = String(credentials?.password ?? "");
        if (!username || !password) return null;

        const user = await prisma.user.findUnique({ where: { username } });
        if (!user) return null;

        // Byte-compatible AtomCMS check (argon2id/bcrypt + md5->argon2id upgrade).
        const res = await checkLogin(password, user.password, {
          convertPasswords: env.CONVERT_PASSWORDS,
        });
        if (!res.valid) return null;

        if (res.upgradedHash) {
          await prisma.user.update({
            where: { id: user.id },
            data: { password: res.upgradedHash },
          });
        }

        // Two-factor: if enabled, a valid TOTP code is required. The secret is
        // Laravel-encrypted with APP_KEY (fail closed if it cannot be read).
        if (user.twoFactorConfirmedAt && user.twoFactorSecret) {
          const code = String(credentials?.code ?? "").trim();
          if (!code || !env.APP_KEY) return null;
          try {
            const secret = new LaravelEncrypter(env.APP_KEY).decrypt(user.twoFactorSecret);
            if (!verifyTotp(code, secret)) return null;
          } catch {
            return null;
          }
        }

        return { id: String(user.id), name: user.username, rank: user.rank };
      },
    }),
    // OAuth providers — enabled only when both id + secret are configured.
    ...(env.DISCORD_CLIENT_ID && env.DISCORD_CLIENT_SECRET
      ? [Discord({ clientId: env.DISCORD_CLIENT_ID, clientSecret: env.DISCORD_CLIENT_SECRET })]
      : []),
    ...(env.GOOGLE_CLIENT_ID && env.GOOGLE_CLIENT_SECRET
      ? [Google({ clientId: env.GOOGLE_CLIENT_ID, clientSecret: env.GOOGLE_CLIENT_SECRET })]
      : []),
  ],
  callbacks: {
    async signIn({ user, account }) {
      if (account?.provider === "credentials") return true;
      // OAuth: only allow if a hotel account with this email already exists.
      const email = user.email;
      if (!email) return "/login?error=NoEmail";
      try {
        const dbUser = await prisma.user.findFirst({
          where: { mail: email },
          select: { id: true },
        });
        return dbUser ? true : "/login?error=NoAccount";
      } catch {
        return "/login?error=Unavailable";
      }
    },
    async jwt({ token, user, account }) {
      if (user && account?.provider === "credentials") {
        token.rank = (user as { rank?: number }).rank;
      } else if (user?.email) {
        // OAuth: bind the session to the matching hotel account.
        try {
          const dbUser = await prisma.user.findFirst({
            where: { mail: user.email },
            select: { id: true, rank: true, username: true },
          });
          if (dbUser) {
            token.sub = String(dbUser.id);
            token.rank = dbUser.rank;
            token.name = dbUser.username;
          }
        } catch {
          // leave token as-is on lookup failure
        }
      }
      return token;
    },
    session({ session, token }) {
      if (token.sub && session.user) session.user.id = token.sub;
      if (typeof token.rank === "number" && session.user) session.user.rank = token.rank;
      return session;
    },
  },
});