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

    # 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 "no-referrer-when-downgrade" always;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types
        text/plain
        text/css
        text/xml
        text/javascript
        application/json
        application/javascript
        application/xml+rss
        application/atom+xml
        image/svg+xml;

    # API proxy to backend service
    location /api/ {
        proxy_pass http://backend:8000/api/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        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;
        proxy_cache_bypass $http_upgrade;
        proxy_read_timeout 90;
    }

    # WebSocket proxy for real-time features
    location /api/v1/ws {
        proxy_pass http://backend:8000/api/v1/ws;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_set_header Host $host;
        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;
        proxy_read_timeout 86400;
    }

    # Serve React app - all routes go to index.html for client-side routing
    location / {
        try_files $uri $uri/ /index.html;
    }

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

    # Don't cache index.html
    location = /index.html {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        expires 0;
    }

    # Deny access to hidden files
    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }
}