import { NextAuthOptions } from 'next-auth'
import CredentialsProvider from 'next-auth/providers/credentials'
import bcrypt from 'bcryptjs'

export const authOptions: NextAuthOptions = {
  secret: process.env.NEXTAUTH_SECRET,
  providers: [
    CredentialsProvider({
      name: 'credentials',
      credentials: {
        username: { label: 'Username', type: 'text' },
        password: { label: 'Password', type: 'password' },
      },
      async authorize(credentials) {
        if (!credentials?.username || !credentials?.password) return null

        const adminUsername = process.env.ADMIN_USERNAME
        let adminPasswordHash = process.env.ADMIN_PASSWORD_HASH

        if (!adminUsername || !adminPasswordHash) {
          throw new Error('Admin credentials not configured')
        }

        // Handle base64 encoded hash to avoid Next.js .env $ expansion issues
        if (adminPasswordHash.startsWith('JDJ') || (!adminPasswordHash.startsWith('$2') && !adminPasswordHash.startsWith('$2a'))) {
          try {
            const decoded = Buffer.from(adminPasswordHash, 'base64').toString('utf8')
            if (decoded.startsWith('$2')) {
              adminPasswordHash = decoded
            }
          } catch {
            // keep original if decoding fails
          }
        }

        if (credentials.username !== adminUsername) return null

        const isValid = await bcrypt.compare(credentials.password, adminPasswordHash)
        if (!isValid) return null

        return { id: '1', name: adminUsername, email: `${adminUsername}@configvault` }
      },
    }),
  ],
  session: { strategy: 'jwt' },
  pages: {
    signIn: '/login',
  },
  callbacks: {
    async jwt({ token, user }) {
      if (user) token.id = user.id
      return token
    },
    async session({ session, token }) {
      if (session.user) (session.user as any).id = token.id
      return session
    },
  },
}