cmd=${1:-help}
ct_name=${2:-}

require_name() {
  if [ -z "$ct_name" ]; then
    echo "usage: ct $cmd <container>" >&2
    exit 1
  fi
}

case "$cmd" in
  list)
    sep() { printf '%0.s-' {1..60}; printf '\n'; }
    uptime_str() {
      awk '{s=int($1);d=int(s/86400);h=int((s%86400)/3600);m=int((s%3600)/60);
        if(d>0)printf "%d days %d hours %d minutes",d,h,m;
        else if(h>0)printf "%d hours %d minutes",h,m;
        else printf "%d minutes",m}' /proc/uptime
    }

    printf 'HOST: %s  UP: %s\n' "$(hostname)" "$(uptime_str)"
    sep

    printf 'CONTAINERS\n'
    mapfile -t all_units < <({
      systemctl list-unit-files --no-legend --no-pager --plain 2>/dev/null
      systemctl list-units --all --no-legend --no-pager --plain 2>/dev/null
    } | awk '$1 ~ /^container@.+\.service$/ {print $1}' | sort -u)

    if [ ${#all_units[@]} -gt 0 ]; then
      systemctl show "${all_units[@]}" \
        --property=Id,UnitFileState,ActiveState --no-pager 2>/dev/null \
      | awk '
        /^Id=container@/ { n=$0; sub(/^Id=container@/,"",n); sub(/\.service$/,"",n) }
        /^UnitFileState=/ { f=$0; sub(/^UnitFileState=/,"",f) }
        /^ActiveState=/   { a=$0; sub(/^ActiveState=/,"",a) }
        /^[[:space:]]*$/ { if (n!="") { _print(); n=f=a="" } }
        END              { if (n!="") _print() }
        function _print() {
          start = (f=="enabled") ? "auto" : "manual"
          if      (a=="active")   st="running"
          else if (a=="failed")   st="FAILED"
          else if (a=="inactive") st="stopped"
          else                    st=(a!="") ? a : "not-loaded"
          mid = "-"
          if (a == "active") {
            midcmd = "machinectl show " n " -p Id --value 2>/dev/null"
            got = ""
            midcmd | getline got
            close(midcmd)
            if (got != "") mid = substr(got,1,12) "..."
          }
          printf "  %-35s %-8s %-10s %s\n", n, start, st, mid
        }
      '
    else
      printf '  none\n'
    fi

    sep

    printf 'FAILED UNITS (host)\n'
    failed=$(systemctl list-units --state=failed --no-legend --no-pager --plain 2>/dev/null \
      | awk 'NF>0{print $1}')
    if [ -z "$failed" ]; then printf '  none\n'
    else printf '%s\n' "$failed" | sed 's/^/  /'; fi

    sep

    printf 'FAILED UNITS (containers)\n'
    any_failed=0
    machines=$(machinectl list --no-legend --no-pager 2>/dev/null | awk 'NF>0{print $1}')
    for m in $machines; do
      ct_failed=$(sudo systemctl -M "$m" list-units --state=failed \
        --no-legend --no-pager --plain 2>/dev/null \
        | awk 'NF>0 && $1!~/^container@/{print $1}' || true)
      if [ -n "$ct_failed" ]; then
        printf '  [%s]\n' "$m"
        printf '%s\n' "$ct_failed" | sed 's/^/    /'
        any_failed=1
      fi
    done
    [ "$any_failed" -eq 0 ] && printf '  none\n'

    sep

    df -h /persist | awk 'NR==2{printf "DISK  %s used / %s total (%s)\n",$3,$2,$5}'
    free -h | awk '/^Mem:/{printf "MEM   %s used / %s total\n",$3,$2}'
    ;;
  start)
    require_name
    sudo systemctl start "container@$ct_name"
    ;;
  stop)
    require_name
    sudo systemctl stop "container@$ct_name"
    ;;
  restart)
    require_name
    sudo systemctl restart "container@$ct_name"
    ;;
  status)
    require_name
    machinectl status "$ct_name"
    ;;
  logs)
    require_name
    shift 2
    sudo journalctl -M "$ct_name" --no-hostname "$@"
    ;;
  shell)
    require_name
    exec sudo machinectl shell "$ct_name"
    ;;
  attach)
    require_name
    leader=$(machinectl show "$ct_name" -p Leader --value 2>/dev/null)
    if [ -z "$leader" ] || [ "$leader" = "0" ]; then
      printf 'error: container %s is not running\n' "$ct_name" >&2
      exit 1
    fi
    exec sudo nsenter -m -t "$leader" -- dtach -a -r none /run/ct-attach/attach.sock
    ;;
  *)
    printf 'usage: ct <cmd> [container]\n\n'
    printf '  %-9s %-13s %s\n' \
      "list"    ""             "list all containers with state (running/stopped/FAILED)" \
      "start"   "<container>"  "start a container" \
      "stop"    "<container>"  "stop a container" \
      "restart" "<container>"  "restart a container" \
      "status"  "<container>"  "show container status" \
      "logs"    "<container>"  "view logs (extra args forwarded to journalctl)" \
      "shell"   "<container>"  "open a shell" \
      "attach"  "<container>"  "attach to Minecraft console (detach: Ctrl+\\)"
    ;;
esac