server {
    listen 80;
    server_name localhost;

    root /usr/share/nginx/html;
    index index.html;

    # API proxy
    location /api {
        proxy_pass http://backend:5000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }

    # Service Worker - no caching!
    location = /sw.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
        add_header Service-Worker-Allowed "/";
    }

    # PWA Manifest
    location = /manifest.json {
        add_header Cache-Control "public, max-age=86400";
        add_header Content-Type "application/manifest+json";
    }

    # React routing
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Cache static assets
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}