#!/bin/sh -e

# This script will setup the build dir based on the current git branch and the
# directory auto-build-save/$BRANCH.  We don't use a symlink for the build dir
# because we want to maximize the ccache reuse, so all builds must happen in
# the same real dir.  When a dir is moved out of auto-build-save/$BRANCH to the
# build dir, it is replaced with a symlink so that it can still be found under
# that dir.  The build dir also gets a .branch -> $BRANCH symlink so that we
# can figure out the current build dir's branch.

# To get started, just clone the rsync git repo and create the auto-build-save
# dir.  If you have an existing git checkout and it is not in a pristine state,
# run "make distclean" before creating the auto-build-save dir.

auto_top='auto-build-save'
if test -d $auto_top && test -d .git; then
    desired_branch=`git rev-parse --abbrev-ref HEAD | tr / %`
    if test "$desired_branch" = HEAD; then
	echo "ERROR: switch to the right build dir manually when in detached HEAD mode." 1>&2
	exit 1
    fi
    auto_dir="$auto_top/$desired_branch"
    if test -d build; then
	cur_branch=`readlink build/.branch`
    else
	cur_branch='/'
    fi
    if test "$desired_branch" != "$cur_branch"; then
	if test "$cur_branch" != /; then
	    rm -f "$auto_top/$cur_branch"
	    mv build "$auto_top/$cur_branch"
	fi
	test -d "$auto_dir" || mkdir "$auto_dir"
	test -h "$auto_dir/.branch" || ln -s "$desired_branch" "$auto_dir/.branch"
	mv "$auto_dir" build
	ln -s ../build "$auto_dir"
    fi
    if test ! -h Makefile; then
	rm -f Makefile
	ln -s packaging/auto-Makefile Makefile
    fi
    echo $desired_branch
fi