#!/bin/bash
set -e

NAME=systemd
UPSTREAM=git://anongit.freedesktop.org/systemd/systemd
REFDIR="$HOME/git/systemd"  # for faster cloning, if available


[ -n "$1" ] && HEAD="$1" || HEAD="HEAD"

WORKDIR="$(mktemp -d --tmpdir "$NAME.XXXXXXXXXX")"
trap 'rm -rf $WORKDIR' exit

[ -d "$REFDIR" ] && REFERENCE="--reference $REFDIR"
git clone $REFERENCE "$UPSTREAM" "$WORKDIR"

pushd "$WORKDIR" > /dev/null
read COMMIT_ID COMMIT_SHORTID COMMIT_TITLE <<EOGIT
$(git log ${HEAD}^..${HEAD} --pretty='format:%H %h %s')
EOGIT
popd > /dev/null

echo "Making git snapshot using commit: $COMMIT_SHORTID $COMMIT_TITLE"

DIRNAME="$NAME-git$COMMIT_SHORTID"
git archive --remote="$WORKDIR" --format=tar --prefix="$DIRNAME/" "$COMMIT_ID" | xz -9 > "$DIRNAME.tar.xz"

echo "Written $DIRNAME.tar.xz"