server {
    listen 80;
    server_name localhost;

    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 image/svg+xml;

    # iOS PWA & Security Headers
    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-Content-Type-Options "nosniff";
    add_header Access-Control-Allow-Origin "*";

    # HTML pages must NEVER be cached by browser/CDN
    location / {
        try_files $uri $uri/ /index.html;
        add_header Cache-Control "no-cache, no-store, must-revalidate, max-age=0";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    # Cache Service Worker with no-cache so updates apply immediately
    location = /sw.js {
        add_header Cache-Control "no-cache, no-store, must-revalidate, max-age=0";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    # Static assets with revalidation
    location ~* \.(css|js|json)$ {
        add_header Cache-Control "no-cache, must-revalidate, max-age=0";
        add_header Pragma "no-cache";
        add_header Expires "0";
    }

    # Images & icons
    location ~* \.(svg|png|jpg|jpeg|ico|webp)$ {
        expires 1d;
        add_header Cache-Control "public, max-age=86400";
    }
}