#! /bin/sh -e

. /usr/share/debconf/confmodule
db_capb backup

## Main state machine.
state=0
while :; do
  case $state in

    0)
      db_input medium runlisp/dump-custom-images || :
      ;;

    1)
      db_get runlisp/dump-custom-images
      case $RET in select) ;; *) state=2; continue ;; esac

      ## Determine the configured Lisp systems.
      sects=$(query-runlisp-config -LM)
      unset lisps
      for s in $sects; do
	case $s in @*) continue ;; esac
	if ! query-runlisp-config -M -p$s:dump-image >/dev/null 2>&1
	  then continue; fi
	lisps=${lisps+$lisps, }$s
      done
      db_subst runlisp/selected-implementations lisps "$lisps"

      ## See if the list has changed recently.
      db_get runlisp/available-implementations
      case $RET in
	"$lisps")
	  ch=nil prio=medium
	  ;;
	*)
	  ch=t prio=high
	  db_set runlisp/available-implementations "$lisps"
	  ;;
      esac

      ## Filter nonexistent implementations from the active list.
      db_get runlisp/selected-implementations
      case $RET in
	-)
	  v=$lisps
	  ;;
	*)
	  unset v
	  for i in $(echo "$RET" | tr , " "); do
	    case " $lisps," in *" $i,"*) v=${v+$v, }$i ;; esac
	  done
	  ;;
      esac
      db_set runlisp/selected-implementations "$v"
      case $ch in
	t) db_fset runlisp/selected-implementations seen false ;;
      esac
      db_input $prio runlisp/selected-implementations || :
      ;;

    -1)
      exit 10
      ;;
    *)
      break
      ;;
  esac

  set +e; db_go; rc=$?; set -e
  case $rc in
    0) state=$(( $state + 1 )) ;;
    30) state=$(( $state - 1 )) ;;
    *) exit $rc ;;
  esac
done