choosenim

#!/bin/bash
CHOOSE=`realpath $0`                   # make note of our origin
NIM=`nim --hint[Conf]:off --dump.format:json dump config | jq -r .prefixdir`/..
if [ "$NIM" = "null/.." ]; then        # true when the prefixdir is missing
	NIM=`dirname \`which nim\``/../..    # fallback for 1.0 support; see #127
fi
if [ $! -eq 0 ]; then                  # if nim threw an error due to a bad arg,
  exit 1                               # fail so the user can deal with it
fi
cd "$NIM"
if [ -n "$*" ]; then                   # a toolchain was requested
  if [ -d "$*" ]; then                 # the toolchain is available
    rm -f chosen                       # ffs my ln -sf should remove it
    ln -sf "$*" chosen                 # select the chosen toolchain
    if ! [ -f "chosen/bin/$CHOOSE" ]; then
      cp -p "$CHOOSE" chosen/bin       # install choosenim if necessary
    fi
    nim --version                      # emit current toolchain version
    exit 0                             # successful selection of toolchain
  fi
fi
tree -v -d -L 1 --noreport             # report on available toolchains
exit 1                                 # signify failure to switch