server {
    listen 80;
    listen [::]:80;
    server_name localhost;
    
    root /usr/share/nginx/html;
    index index.html index.htm;
    
    # Security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "no-referrer-when-downgrade" always;
    add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;
    
    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_proxied expired no-cache no-store private must-revalidate auth;
    gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml+rss application/javascript;
    
    # Handle client 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";
    }
    
    # Cache manifest files
    location ~* \.(manifest|webmanifest)$ {
        expires 1y;
        add_header Cache-Control "public";
    }
    
    # Disable cache for service worker
    location ~* sw\.js$ {
        expires -1;
        add_header Cache-Control "no-cache, no-store, must-revalidate";
    }
    
    # Health check endpoint
    location /health {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }
}