import { NextResponse, type NextRequest } from 'next/server'
import { locales, defaultLocale } from './src/i18n/config'
import { auth } from './src/lib/auth'

function getLocaleFromHeaders(acceptLanguage: string | null): string {
  if (!acceptLanguage) return defaultLocale;
  
  const languages = acceptLanguage
    .split(',')
    .map(lang => lang.split(';')[0].trim().toLowerCase());
  
  // Check for exact matches first
  for (const lang of languages) {
    if (locales.includes(lang as any)) {
      return lang;
    }
  }
  
  // Check for language prefix matches (e.g., 'zh-CN' -> 'zh')
  for (const lang of languages) {
    const prefix = lang.split('-')[0];
    if (locales.includes(prefix as any)) {
      return prefix;
    }
  }
  
  return defaultLocale;
}

export async function middleware(request: NextRequest) {
  let response = NextResponse.next({
    request: {
      headers: request.headers,
    },
  })

  // Handle locale detection and cookie setting
  const currentLocale = request.cookies.get('locale')?.value;
  const acceptLanguage = request.headers.get('accept-language');
  
  if (!currentLocale) {
    const detectedLocale = getLocaleFromHeaders(acceptLanguage);
    response.cookies.set('locale', detectedLocale, {
      maxAge: 60 * 60 * 24 * 365, // 1 year
      httpOnly: false,
      secure: process.env.NODE_ENV === 'production',
      sameSite: 'lax',
    });
  }

  // Better Auth session check
  try {
    await auth.api.getSession({
      headers: request.headers
    })
  } catch (error) {
    // Session validation failed, but we continue
    console.debug('Session validation failed in middleware:', error)
  }

  return response
}

export const config = {
  matcher: [
    '/((?!_next/static|_next/image|favicon.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)',
  ],
}