srcdir="$1"

# If no git repo try to read from the existing git_version.h, for building from tarballs
if ! test -d "${srcdir}/.git"; then
  version_h_path="${srcdir}/build/git_version.h"
  if test -f "${version_h_path}"; then
    while read line; do
      set -- $line
      export $2=$(echo $3 | sed 's/"//g')
    done < "${version_h_path}"
    if test x$BUILD_GIT_VERSION_NUMBER != x -a x$BUILD_GIT_VERSION_STRING != x; then
      export VERSION_SOURCE="from cached git_version.h"
      return 0
    else
      echo "invalid git_version.h"
      exit 2
    fi
  else
    echo "git repo not found and no cached git_version.h"
    exit 2
  fi
fi

last_svn_revision=6962
last_svn_hash="16cd907fe7482cb54a7374cd28b8501f138116be"

git_revision=$(expr $last_svn_revision + $(git log --pretty=oneline $last_svn_hash..HEAD 2>/dev/null | wc -l))
git_version_str=$(git describe --exact-match 2> /dev/null)
if test x$git_version_str != x; then
  git_version_str="${git_version_str##v}"
  tagged_release=1
else
  git_branch="$(git symbolic-ref HEAD 2> /dev/null)" || git_branch="(unnamed branch)"
  git_branch="${git_branch##refs/heads/}"
  git_hash=$(git rev-parse --short HEAD)

  git_version_str="${git_revision}-${git_branch}-${git_hash}"
  tagged_release=0
fi

new_version_h="\
#define BUILD_GIT_VERSION_NUMBER ${git_revision}
#define BUILD_GIT_VERSION_STRING \"${git_version_str}\"
#define TAGGED_RELEASE ${tagged_release}"

# may not exist yet for out of tree builds
mkdir -p build
version_h_path="build/git_version.h"

# Write it only if it's changed to avoid spurious rebuilds
# This bizzare comparison method is due to that newlines in shell variables are very exciting
case "$(cat ${version_h_path} 2> /dev/null)"
in
  "${new_version_h}");;
  *) echo "${new_version_h}" > "${version_h_path}"
esac

export BUILD_GIT_VERSION_NUMBER="${git_revision}"
export BUILD_GIT_VERSION_STRING="${git_version_str}"
export VERSION_SOURCE="from git"

cat << EOF > build/git_version.xml
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <GitVersionNumber>${git_revision}</GitVersionNumber>
    <GitVersionString>${git_version_str}</GitVersionString>
  </PropertyGroup>
</Project>
EOF