#! /usr/bin/env nix-shell
#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/6616de389ed55fba6eeba60377fc04732d5a207c.tar.gz -i bash -p git gnugrep gnused findutils nixfmt

nixfmt_args=()
files=()

for arg do
    case $arg in
        -h)
            echo "$0 [-c]"
            exit
            ;;
        -c)
            nixfmt_args+=("$arg")
            ;;
        -*)
            echo "unrecognised flag: $arg" >&2
            exit 1
            ;;
        *)
            files+=("$arg")
            ;;
    esac
done

# The excludes are for files touched by open pull requests and we want
# to avoid merge conflicts.
excludes=(
    modules/default.nix
    modules/files.nix
    modules/home-environment.nix
    modules/lib/default.nix
    modules/lib/file-type.nix
    modules/misc/news.nix
    modules/programs/ssh.nix
    modules/programs/zsh.nix
    tests/default.nix
)

exclude_args=()
for e in "${excludes[@]}"; do
    exclude_args+=(-e "$e")
done

git_root=$(git rev-parse --show-toplevel)

git ls-files -z --cached --others --full-name -- "${files[@]}" |
    grep -z '\.nix$' |
    grep -z -v "${exclude_args[@]}" |
    sed -z "s|^|$git_root/|" |
    xargs -0 nixfmt "${nixfmt_args[@]}"