#!/usr/bin/env bash
set -euo pipefail
# POS: network checkport — Check TCP port connectivity

usage() {
    cat <<EOF
Usage: pos network checkport <ip:port>

Check if a TCP port is open on a remote host.

Examples:
  pos network checkport 192.168.1.1:80
  pos network checkport 10.0.0.5:443
EOF
    exit 0
}

case "${1:-}" in
    -h|--help|"") usage ;;
esac

target="$1"

if [[ "$target" != *:* ]]; then
    echo "ERROR: Expected <ip:port> format, got '$target'"
    echo "Usage: pos network checkport <ip:port>"
    exit 1
fi

ip="${target%:*}"
port="${target#*:}"

if [[ -z "$ip" || -z "$port" ]]; then
    echo "ERROR: Invalid target '$target'"
    exit 1
fi

echo "Checking $ip:$port ..."
echo

if timeout 2 bash -c "cat < /dev/null > /dev/tcp/$ip/$port" 2>/dev/null; then
    echo "OPEN ✔ $ip:$port"
else
    echo "CLOSED ✖ $ip:$port"
fi