#!/bin/sh -eu

PROG="${0##*/}"

fatal()
{
	printf %s\\n "$PROG: $*" >&2
	exit 1
}

workdir=
exit_handler()
{
	local rc=$?
	trap - EXIT
	[ -z "$workdir" ] || rm -rf "$workdir"
	exit $rc
}

signal_handler()
{
	echo "$PROG: Interrupted" >&2
	exit 1
}

trap exit_handler EXIT
trap signal_handler SIGHUP SIGPIPE SIGINT SIGTERM SIGQUIT

workdir=`mktemp -td cvs2git.XXXXXXXXXX` ||
	fatal "failed to create working directory"

rewrite_head()
{
	local head="$1" && shift
	local new_head="$1" && shift

	git checkout "old/$head"
	cg-admin-rewritehist \
		--msg-filter 'perl -0777 -pe "s/^\\n+//s"' \
		--commit-filter '
		if { [ "$#" = 3 ] &&
			[ -z "$(git-diff-tree "$GIT_COMMIT^1" "$GIT_COMMIT")" ]
		} || [ "$GIT_AUTHOR_NAME" = "cvs2svn" ]
		then
			shift
			while [ -n "$1" ]; do
				shift; echo "$1"; shift
			done
		elif [ "$#" = 1 ] &&
			[ "$1" = 4b825dc642cb6eb9a060e54bf8d69288fbee4904 ]
		then
			shift
		else
			msg="$(mktemp -t rewrite.XXXXXXXXXX)"
			cat >"$msg"
			if grep -qs "file .* was added on branch .* on " "$msg"
			then
				shift
				while [ -n "$1" ]; do
					shift; echo "$1"; shift
				done
			else
				git-commit-tree "$@" <"$msg"
			fi
			rm -f "$msg"
		fi
		' "$new_head"
}

[ "$#" = 2 ] || fatal "usage: $PROG <cvs-repo> <git-repo>"
cvs_repo="$1"
git_repo="$2"
[ -d "$cvs_repo" ] || fatal "CVS repository '$cvs_repo' not found"
[ -e "$git_repo" ] && fatal "GIT repository '$git_repo' already exists" ||:

svn_repo="$workdir/svn"
authors="$(readlink -ev Authors)" ||
	fatal "Authors file not found"

cvs2svn -s "$svn_repo" --username=cvs2svn --keywords-off --encoding=utf-8 \
	"$cvs_repo"

mkdir -p "$git_repo"
cd "$git_repo"
git-init-db
git-svn multi-init -b branches --no-metadata -A "$authors" \
	file://"$svn_repo"
git-svn multi-fetch --no-metadata -A "$authors"
rm -rf "$svn_repo"

rm -f .git/refs/heads/master
mv .git/refs/remotes .git/refs/heads/old
mv .git/refs/heads/old/{trunk,master}

for head in `ls -1 .git/refs/heads/old`; do
	new_head="$(echo "$head" | sed 's/_/./g')" 
	case "$new_head" in
		std-2.4.22-alt12.kdb)	continue 			;;
		std-2.4.22-patches)	new_head='alt-linux-2.3'	;;
		Master-2.4)		new_head='alt-linux-2.4'	;;
		branch-3.0)		new_head='alt-linux-3.0'	;;
	esac
	rewrite_head "$head" "$new_head"
done

git checkout master
rm -rf .git/refs/heads/old
git repack -a -d -l -f
git prune