#!/bin/sh
exec >&2
[ "${NIXREDO_ROOT-x}" != x ] || { printf "Set NIXREDO_ROOT. Set empty to use global nix store\n"; exit 127; }
if [ $# -eq 0 ]; then set -- all; fi
if [ -e "$1.nix" ]; then
  set -e
  set -- "$1" "$1" "$1.redo.tmp"
  f=$(realpath "$1.nix")
  out=$(nix -vL --show-trace build ${NIXREDO_ROOT:+--store "$NIXREDO_ROOT"} \
            --option auto-optimise-store true --option substituters daemon \
            --impure --json --no-link \
            --expr "import @buildernix@ { cwd = \"$PWD/\"; rargs = [ \"$1\" \"$1\" ];} \"$f\"" |
            @jq@ -r '.[0].outputs.out')
  [ -n "$out" ] || exit 127
  rm -rf "$3"
  ln -s "${NIXREDO_ROOT+$NIXREDO_ROOT}$out" "$3"
  # ln "${NIXREDO_ROOT+$NIXREDO_ROOT/}$out" "$3"
  # chmod +w "$3"
  # touch "$3"
  mv "$3" "$1"
elif [ -e "$1" ]; then
  :
else
  printf "Error: No rule to build %s\n" "$1"
  exit 127
fi