server {
    listen 80;
    listen [::]:80;
    server_name _;

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

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_proxied expired no-cache no-store private auth;
    gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml application/javascript application/json;
    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;

    # Health check endpoint
    location /health {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }

    # Static assets - long cache
    location /assets/ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        try_files $uri =404;
    }

    # Favicon and static files
    location ~* \.(ico|svg|png|jpg|jpeg|gif|webp|woff|woff2|ttf|eot)$ {
        expires 1M;
        add_header Cache-Control "public";
        try_files $uri =404;
    }

    # JavaScript and CSS with content hash
    location ~* \.(js|css)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        try_files $uri =404;
    }

    # API proxy (if needed - configure backend URL)
    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 86400s;
        proxy_send_timeout 86400s;
    }

    # WebSocket proxy
    location /ws/ {
        proxy_pass http://backend:8000/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 86400s;
        proxy_send_timeout 86400s;
    }

    # SPA fallback - serve index.html for all routes
    location / {
        try_files $uri $uri/ /index.html;

        # No cache for index.html
        location = /index.html {
            expires -1;
            add_header Cache-Control "no-store, no-cache, must-revalidate";
        }
    }

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

    # Error pages
    error_page 404 /index.html;
    error_page 500 502 503 504 /50x.html;
    location = /50x.html {
        root /usr/share/nginx/html;
    }
}