#!/bin/sh -e
  # Helper to bypass AC_ERLANG_CHECK_LIB
  #
  # Ejabberd releases do not download specific versions of its erlang
  # dependencies.  Instead, it clones the master branch of a git
  # repository and asks erl to provide the library version.  However,
  # the target erl program cannot be called from the host. So, this
  # script aims at finding the library version installed on the target,
  # without calling erlang.
  
  usage() {
      cat <<EOF
  Usage:
          $0 library
  Look for Erlang's library in TARGET_DIR/usr/lib/erlang/lib.
  
  If the library is found, it returns the path to the latest version,
  relative to TARGET_DIR. Otherwise, it returns "not found".
  
  If there are several versions, it returns an error because it does not
  know which one Erlang uses.
  
  EOF
  }
  
  die () {
      echo "$@" >&2
      exit 1
  }
  
  if [ $# -ne 1 ]; then
      usage
      exit 0
  else
      library="$1"
  fi
  
  target_dir="${TARGET_DIR:-output/target}"
  
  [ -d "$target_dir" ] || die "TARGET_DIR is not a directory. Please \
  specify the TARGET_DIR environment variable."
  
  case "$(ls -1d -- "$target_dir/usr/lib/erlang/lib/$library-"* | wc -l)" in
      0)
          echo "not found"
          ;;
      1)
          echo "$target_dir/usr/lib/erlang/lib/$library-"* \
              | sed -e "s,^$target_dir,,"
          ;;
      *)
          die "Several versions of $library have been found. Please \
          remove the unused ones."
          ;;
  esac