java-select

#!/bin/sh

BASE_DIR="$HOME/.java-select"

die() {
  echo >&2 "$@"
  exit 1
}

# On Mac "echo -n" doesn't work in sh without COMMAND_MODE=legacy (man 5 compat).
# This workaround allows to use echo from GNU coreutils.
echo() {
  `which echo` "$@"
}

change() {
  [ "$#" -eq 1 ] || die "1 argument required, $# provided"
  target="${1}"

  if [[ -d "${BASE_DIR}/versions/${target}" ]]; then
    local tmpf="${BASE_DIR}/current.new"
    ln -s "${BASE_DIR}/versions/${target}" "${tmpf}" || die "Unable to create temporary symlink"
    if ! mv -T "${tmpf}" "${BASE_DIR}/current"; then
      die "Unable to replace symlink with ${target}"
    fi
    java -version
  else
    die "Target '${target}' doesn't appear to be valid!"
  fi
}

list() {
  local current=$(readlink "${BASE_DIR}/current")
  current="${current##*/}"

  for candidate in $(ls  "${BASE_DIR}/versions") ; do
    if [[ -d "${BASE_DIR}/versions/${candidate}" ]]; then
      if [ $1 -eq 1 ]; then
        if [[ "${current}" = "${candidate}" ]]; then
          echo -e -n " \e[1;33m*\e[0m "
        else
          echo -n "   "
        fi
      fi
      echo "${candidate}"
    fi
  done
}

if [ "$1" == "--completion" ]; then
  list 0
elif [ "$#" -eq 1 ]; then
  change $1
else
  list 1
fi