upstream backend {
    server backend:5000;
}

server {
    listen 80;
    server_name _;
    client_max_body_size 100M;

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

server {
    listen 443 ssl http2;
    server_name _;
    client_max_body_size 100M;

    # SSL certificates (mount via certbot / Let's Encrypt)
    ssl_certificate /etc/nginx/ssl/fullchain.pem;
    ssl_certificate_key /etc/nginx/ssl/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_prefer_server_ciphers on;
    ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256;

    # Security headers
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;
    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;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=()" always;
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-inline' https://pagead2.googlesyndication.com https://www.googletagmanager.com https://www.google-analytics.com; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com; img-src 'self' data: blob: https://pagead2.googlesyndication.com https://www.google-analytics.com; connect-src 'self' https://www.google-analytics.com https://pagead2.googlesyndication.com; frame-src https://googleads.g.doubleclick.net https://tpc.googlesyndication.com; frame-ancestors 'self'" always;

    # Gzip
    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml text/javascript image/svg+xml;
    gzip_min_length 1000;

    # API requests → Flask
    location /api/ {
        proxy_pass http://backend;
        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 300s;
        proxy_send_timeout 300s;
    }

    # Frontend static files
    location / {
        root /usr/share/nginx/html;
        try_files $uri $uri/ /index.html;

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

    # Health check
    location /health {
        proxy_pass http://backend/api/health;
    }
}