#!/usr/bin/env bash

set -euo pipefail

DIR="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"

target_commit="${1:-unset}"

if [ "unset" = "$target_commit" ]; then
  target_commit=$(curl --silent \
                       -H "Accept: application/vnd.github+json" \
                       -H "X-GitHub-Api-Version: 2022-11-28" \
                       https://api.github.com/repos/NixOS/nixpkgs/branches/nixpkgs-unstable \
                  | jq -r .commit.sha)
fi

archive_sha=$(nix-prefetch-url https://github.com/NixOS/nixpkgs/archive/$target_commit.tar.gz --unpack 2>/dev/null)

tmp=$(mktemp)

jq -n \
   --arg branch nixpkgs-unstable \
   --arg repo nixpkgs \
   --arg owner NixOS \
   --arg rev $target_commit \
   --arg sha256 $archive_sha \
   '{$owner, $repo, $branch, $rev, $sha256}' \
   > $tmp

mv $tmp $DIR/../nix/nixpkgs/default.src.json