middleware.ts

import { NextResponse, NextRequest } from 'next/server'
import { COOKIE_NAME, QUERY_PARAM, locales, type Locale, defaultLocale } from '@/i18n/config'

export async function middleware(request: NextRequest) {
  try {
    const { pathname } = request.nextUrl

    // Language detection
    let locale: Locale = defaultLocale
    const queryLocale = request.nextUrl.searchParams.get(QUERY_PARAM)

    // Priority: Query param > Cookie > Default
    if (queryLocale && locales.includes(queryLocale as Locale)) {
      locale = queryLocale as Locale
    } else {
      const cookieLocale = request.cookies.get(COOKIE_NAME)?.value
      if (cookieLocale && locales.includes(cookieLocale as Locale)) {
        locale = cookieLocale as Locale
      }
    }

    // Create response with locale cookie
    const response = NextResponse.next({
      request: { headers: request.headers },
    })

    // Set locale cookie if not already set or different
    if (!request.cookies.get(COOKIE_NAME) || request.cookies.get(COOKIE_NAME)?.value !== locale) {
      response.cookies.set(COOKIE_NAME, locale, {
        maxAge: 31536000, // 1 year
        path: '/',
        sameSite: 'lax',
      })
    }

    // Skip auth check for public API routes
    const publicApiRoutes = ['/api/billing/plans', '/api/generate/questions']
    if (publicApiRoutes.some(route => pathname.startsWith(route))) {
      return response
    }

    // Skip auth check if Supabase is not configured
    const supabaseUrl = process.env.NEXT_PUBLIC_SUPABASE_URL
    const supabaseAnonKey = process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY

    if (!supabaseUrl || !supabaseAnonKey) {
      console.warn('Supabase not configured, skipping auth check in middleware')
      return response
    }

    // Dynamic import to avoid build-time errors
    const { createClient } = await import('@/lib/supabase/server')
    const supabase = await createClient()
    const { data: { user } } = await supabase.auth.getUser()

    const protectedRoutes = ['/drafts']
    const isProtectedRoute = protectedRoutes.some(route => pathname.startsWith(route))

    const authRoutes = ['/login', '/signup']
    const isAuthRoute = authRoutes.includes(pathname)

    if (!user && isProtectedRoute) {
      const loginUrl = new URL('/login', request.url)
      loginUrl.searchParams.set('redirectTo', pathname)
      loginUrl.searchParams.set(QUERY_PARAM, locale)
      return NextResponse.redirect(loginUrl)
    }

    if (user && isAuthRoute) {
      const draftsUrl = new URL('/drafts', request.url)
      draftsUrl.searchParams.set(QUERY_PARAM, locale)
      return NextResponse.redirect(draftsUrl)
    }

    return response
  } catch (error) {
    console.error('Middleware error:', error)
    // Return a basic response to avoid 500 error
    return NextResponse.next()
  }
}

export const config = {
  matcher: [
    '/((?!_next|[^?]*\\.(?:html?|css|js(?!on)|jpe?g|webp|png|gif|svg|ttf|woff2?|ico|csv|docx?|xlsx?|zip|webmanifest)).*)',
    '/(api|trpc)(.*)',
  ],
}