events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;
    sendfile      on;
    keepalive_timeout 65;

    # Trust NPM as a proxy — replace $remote_addr with the real client IP
    # from X-Forwarded-For when the request comes from NPM's subnet
    real_ip_header    X-Forwarded-For;
    real_ip_recursive on;
    set_real_ip_from  192.168.0.0/16;
    set_real_ip_from  10.0.0.0/8;
    set_real_ip_from  172.16.0.0/12;

    # Log format includes real IP, referrer, and user agent
    log_format main '$remote_addr - [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" fwd="$http_x_forwarded_for"';
    access_log /var/log/nginx/access.log main;

    # Use Docker's internal DNS; valid=10s forces re-resolution after container restarts.
    # Variables in proxy_pass activate this resolver (upstream blocks do not).
    resolver 127.0.0.11 valid=10s ipv6=off;

    server {
        listen 80;
        server_name _;

        client_max_body_size 10M;

        # API — variable forces re-resolution via resolver on each request cycle
        location /api/ {
            set $api http://api:8000;
            proxy_pass $api;
            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 120s;
            proxy_connect_timeout 10s;
        }

        # Next.js static assets (long cache)
        location /_next/static/ {
            set $frontend http://frontend:3000;
            proxy_pass $frontend;
            proxy_cache_valid 200 1d;
            add_header Cache-Control "public, max-age=86400, immutable";
        }

        # Everything else → frontend
        location / {
            set $frontend http://frontend:3000;
            proxy_pass $frontend;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            # WebSocket support (Next.js HMR in dev)
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
        }
    }
}