server {
    listen 80;
    server_name _;
    root /usr/share/nginx/html;
    index index.html;

    # Gzip compression (fallback for clients that don't support Brotli)
    gzip on;
    gzip_vary on;
    gzip_comp_level 6;
    gzip_min_length 256;
    gzip_proxied any;
    gzip_types
        text/plain
        text/css
        text/xml
        text/javascript
        application/javascript
        application/x-javascript
        application/json
        application/xml
        application/wasm
        application/octet-stream
        image/svg+xml
        font/woff2;
    gzip_disable "MSIE [1-6]\.";

    # Security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;

    # NEVER cache index.html and service worker - always fetch fresh
    location = /index.html {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    location = /sw.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    location = /registerSW.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    location = /manifest.webmanifest {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    # Cache static assets with hashed filenames (immutable)
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }

    # Handle SPA routing - all routes serve index.html
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Health check endpoint
    location /health {
        return 200 'OK';
        add_header Content-Type text/plain;
    }
}