#!/bin/sh
# Shell script implementing the Aliens interface for RubyGems.
# Copyright 2009 Michael Homer. Released under the GNU GPL 2 or later.

getversion() {
   prog="$1"
   gem list "$prog" | sed -n -e '/'"$prog"' / { s/.*(\([^),]\+\)[),].*/\1/ p ; q} '
}

in_version_range() {
   lower="$1"
   ver="$2"
   upper="$3"
   [ "$ver" ] || return 1
   [ "$ver" != "$lower" -a "$(GuessLatest "$ver" "$lower")" = "$lower" ] && return 1
   [ "$upper" ] || return 0
   [ "$(GuessLatest "$ver" "$upper")" = "$upper" ] || return 1
   [ "$ver" = "$upper" -a "$ver" != "$lower" ] && return 1
   return 0
}

getinstallversion() {
   prog="$1"
   for V in $(gem list --remote "$prog"  | sed -n -e '/'"$prog"' / { s/.*(\([^)]\+\))/\1/; s/,//g; p }')
   do
      if in_version_range "$2" "$V" "$3"
      then
         echo $V
         return 0
      fi
   done
}

install() {
   prog="$1"
   ver="$2"
   if [ "$ver" ]
   then
      gem install "$prog" --version "$ver"
   else
      gem install "$prog"
   fi
}

command="$1"
prog="$2"

case "$command" in
   --getversion)
      echo $(getversion "$2")
      ;;
   --getinstallversion)
      echo $(getinstallversion "$2" "$3" "$4")
      ;;
   --greater-than)
      ver=$(getversion "$2")
      latest=$(GuessLatest "$ver" "$3")
      [ "$latest" = "$3" ] && exit 1 || exit 0
      ;;
   --met|--within-range|--interval)
      prog="$2"
      lower="$3"
      upper="$4"
      ver=$(getversion "$prog")
	  in_version_range "$lower" "$ver" "$upper"
      ;;
   --have-manager)
      which gem >/dev/null 2>&1 || exit 1
      ;;
   --get-manager-rule)
      echo "Ruby >= 1.9"
      ;;
   --install)
      install "$2" "$3"
      ;;
esac # is ridiculous