#!/usr/bin/env bash
set -euo pipefail

ARTIFACT_DIR="${1:-}"
if [[ -z "$ARTIFACT_DIR" ]]; then
	echo "usage: generate-checksums.sh <artifact-dir>" >&2
	exit 1
fi

if [[ ! -d "$ARTIFACT_DIR" ]]; then
	echo "artifact directory does not exist: $ARTIFACT_DIR" >&2
	exit 1
fi

cd "$ARTIFACT_DIR"

mapfile -t FILES < <(find . -maxdepth 1 -type f | sed 's|^\./||' | grep -v '^SHA256SUMS' | sort)

if [[ ${#FILES[@]} -eq 0 ]]; then
	echo "no files to checksum in $ARTIFACT_DIR" >&2
	exit 1
fi

: >SHA256SUMS
for FILE in "${FILES[@]}"; do
	if command -v sha256sum >/dev/null 2>&1; then
		HASH="$(sha256sum "$FILE" | awk '{ print $1 }')"
	else
		HASH="$(shasum -a 256 "$FILE" | awk '{ print $1 }')"
	fi
	printf '%s  %s\n' "$HASH" "$FILE" >>SHA256SUMS
done

cp SHA256SUMS SHA256SUMS.txt