#!/usr/bin/env bash
# 001-create-swap - Create 2GB swap + fstab entry + vm.swappiness=10
# up:   enable swap (skipped if swap already active)
# down: disable swap and remove file/fstab/sysctl entries
set -euo pipefail

case "${1:-}" in
  up)
    if swapon --show --noheadings | grep -q .; then
      echo "    swap already active - skipping"
      exit 0
    fi
    if [[ ! -f /swapfile ]]; then
      fallocate -l 2G /swapfile || {
        dd if=/dev/zero of=/swapfile bs=1M count=2048 status=none
      }
      chmod 600 /swapfile
      mkswap /swapfile >/dev/null
    fi
    swapon /swapfile
    grep -q '^/swapfile' /etc/fstab || echo '/swapfile none swap sw 0 0' >> /etc/fstab
    if ! grep -rqs 'vm.swappiness' /etc/sysctl.d/ /etc/sysctl.conf; then
      echo 'vm.swappiness=10' > /etc/sysctl.d/99-swap.conf
      sysctl -p /etc/sysctl.d/99-swap.conf >/dev/null
    fi
    echo "    swap 2GB enabled + fstab entry + vm.swappiness=10"
    ;;
  down)
    swapoff /swapfile
    rm -f /swapfile
    sed -i '\|^/swapfile|d' /etc/fstab
    grep -q '^vm.swappiness=10$' /etc/sysctl.d/99-swap.conf 2>/dev/null \
      && rm -f /etc/sysctl.d/99-swap.conf || true
    echo "    swap removed"
    ;;
esac