server {
    listen 80;
    server_name example.com;
    root /var/www/html;

    # Redirect HTTP to HTTPS
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl;
    http2 on;   # nginx ≥ 1.25.1; en versiones anteriores: listen 443 ssl http2;
    server_name example.com;
    root /var/www/html;

    ssl_certificate     /path/to/cert.pem;
    ssl_certificate_key /path/to/key.pem;
    ssl_protocols TLSv1.2 TLSv1.3;

    # Security headers (no rompen una SPA; una CSP completa depende de tu app)
    server_tokens off;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header X-Frame-Options "DENY" always;
    add_header Content-Security-Policy "frame-ancestors 'none'; object-src 'none'; base-uri 'self'" always;
    add_header Strict-Transport-Security "max-age=31536000" always;   # añade includeSubDomains cuando TODOS los subdominios vayan por https

    # Nunca servir ficheros ocultos: .git/, .env, .htpasswd… (salvo .well-known)
    location ~ /\.(?!well-known) {
        deny all;
    }

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml;

    # Cache static assets — «immutable» solo es correcto si el nombre lleva hash (main-3F2A1B.js)
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        # Repetidas: un add_header aquí anula las del server
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header X-Frame-Options "DENY" always;
        add_header Content-Security-Policy "frame-ancestors 'none'; object-src 'none'; base-uri 'self'" always;
        add_header Strict-Transport-Security "max-age=31536000" always;   # añade includeSubDomains cuando TODOS los subdominios vayan por https
    }

    location / {
        try_files $uri $uri/ /index.html;
    }
}