#!/bin/sh

determineGitRevision()
{
	haikuTop=$1
	haikuBuildOutputDir=$2

	revision=`cat ${haikuBuildOutputDir}/haiku-revision 2>/dev/null`
	lastBuiltRevision=`cat ${haikuBuildOutputDir}/last-built-revision \
		2>/dev/null`
	localRev=`git rev-list -n1 HEAD`

	# only determine the haiku-revision if anything has changed from
	# last build
	if [ -z "$revision" -o "$lastBuiltRevision" != "$localRev" ]; then
		haikuBranch=`git describe --abbrev=0 --match 'haiku/*.base' \
			| $SED -re 's/haiku\/(.*)\.base/\1/'`
		if [ -z "$haikuBranch" ]; then
			echo "*** unable to find haiku branch the build is based on"
			exit 1;
		fi
		haikuTip=`git rev-list -n1 haiku/${haikuBranch}.tip`
		if [ -z "$haikuTip" ]; then
			echo "*** unable to find tip of haiku branch the build is based on"
			exit 1;
		fi

		# make sure that haiku-tip matches the remote tracking branch,
		# otherwise the tag hasn't been fetched/updated and we should
		# print a warning
		trackingBranch=`git branch -r --contains $haikuTip \
			| grep -v -- '->' | tr -d ' '`
		if [ -z "$trackingBranch" ]; then
			echo "*** unable to find tracking branch the build is based on"
			exit 1;
		fi
		haikuTipLag=`git rev-list --count ${haikuTip}..$trackingBranch`
		if [ "$haikuTipLag" != "0" ]; then
			echo "*********************************************************"
			echo "!!! haiku/${haikuBranch}.tip is $haikuTipLag behind \
				remote tracking branch"
			echo "!!! you may want to 'git fetch --tags' to update the tag"
			echo "*********************************************************"
		fi

		# the haiku revision the HEAD is based on is the nearest common ancestor
		# of these two (i.e. the merge base)
		haikuBaseRev=`git merge-base $localRev $haikuTip`
		if [ -z "$haikuTip" ]; then
			echo "*** unable to find merge-base for haiku tip and build"
			exit 1;
		fi

		# the revision we use is the description of HEAD with
		# respect to the root of the current branch
		revision=`git describe --dirty --long --match=haiku/$haikuBranch`
		if [ "$localRev" != "$haikuBaseRev" ]; then
			# HEAD is not a changeset from Haiku's central repo, so we add
			# a description of the changeset in Haiku's repo HEAD is based on
			haikuBaseRevDescr=`git describe --long --match=haiku/$haikuBranch \
				$haikuBaseRev`
			revision="$revision [$haikuBaseRevDescr]"
		fi
		echo $localRev >${haikuBuildOutputDir}/last-built-revision
	fi
}


determineHaikuRevision()
{
	haikuTop=$1
	haikuBuildOutputDir=$2

	case `uname` in
	Darwin)
		SED=gsed
		;;
	*)
		SED=sed
		;;
	esac
	export SED

	originalDir=`pwd`
	cd ${haikuTop}
	export LC_ALL=C
	if [ -d .svn ]; then
		revision=`svn info 2>/dev/null | grep Revision | awk '{printf $2}'`
	elif [ -d .git/svn ]; then
		revision=`git svn info 2>/dev/null | grep Revision | awk '{printf $2}'`
	elif [ -d .git ]; then
		determineGitRevision $haikuTop $haikuBuildOutputDir
	elif [ -d .hg ]; then
		# Try searching hg log for last svn commit
		# Extract from "(svn r12345) ..." line
		revision=`(cd ${haikuTop} &&
			hg log --no-merges --template "{desc|firstline}\n") 2> /dev/null |
			grep --max-count=1 "(svn r" |
			$SED -n -e 's,(svn r\(.*\)).*,\1,p'`
	fi
	if [ "$revision" = "" ]; then
		revision=0
	fi
	echo $revision >${haikuBuildOutputDir}/haiku-revision
	cd $originalDir
}