#! /usr/bin/env sh

set -eu

notify-send "Running nix via the wrapper."

if [ "$_NIX_WRAPPER_FALLBACK" = "true" ]; then
    # Allow skipping the size check.
    nix "$@"
else
    usage="$(btrfs filesystem usage /nix --raw 2>/dev/null)"
    avail="$(echo "$usage" | grep 'Device size:' | cut -f 3 | sed 's/ //g')"
    used="$(echo "$usage" | grep 'Used:' | cut -f 4 | head -n 1 | sed 's/ //g')"
    perc="$(printf "scale=3\n%d / %d\n" "$used" "$avail" | bc)"
    perc="$(printf "%d * 100\n" "$perc" | bc)"

    if test -gt "$perc" "0.2"; then
        nix "$@"
    else
        echo "Not enough space free, in nix store: Only, $perc is still free."
        exit 3
    fi
fi

# vim: ft=sh