#
# Internal file for GetGitRevisionDescription.cmake
#
# Requires CMake 2.6 or newer (uses the 'function' command)
#
# Original Author:
# 2009-2010 Ryan Pavlik <rpavlik@iastate.edu> <abiryan@ryand.net>
# http://academic.cleardefinition.com
# Iowa State University HCI Graduate Program/VRAC
#
# Copyright 2009-2012, Iowa State University
# Copyright 2011-2015, Contributors
# Distributed under the Boost Software License, Version 1.0.
# (See accompanying file LICENSE_1_0.txt or copy at
# http://www.boost.org/LICENSE_1_0.txt)
# SPDX-License-Identifier: BSL-1.0

set(HEAD_HASH)

file(READ "@HEAD_FILE@" HEAD_CONTENTS LIMIT 1024)

string(STRIP "${HEAD_CONTENTS}" HEAD_CONTENTS)
if (HEAD_CONTENTS MATCHES "ref")
  # named branch
  string(REPLACE "ref: " "" HEAD_REF "${HEAD_CONTENTS}")
  if (EXISTS "@GIT_DIR@/${HEAD_REF}")
    configure_file("@GIT_DIR@/${HEAD_REF}" "@GIT_DATA@/head-ref" COPYONLY)
  else()
    configure_file("@GIT_DIR@/packed-refs" "@GIT_DATA@/packed-refs" COPYONLY)
    file(READ "@GIT_DATA@/packed-refs" PACKED_REFS)
    if (PACKED_REFS MATCHES "([0-9a-z]*) ${HEAD_REF}")
      set(HEAD_HASH "${CMAKE_MATCH_1}")
    endif()
  endif()
else()
  # detached HEAD
  configure_file("@GIT_DIR@/HEAD" "@GIT_DATA@/head-ref" COPYONLY)
endif()

if (NOT HEAD_HASH)
  file(READ "@GIT_DATA@/head-ref" HEAD_HASH LIMIT 1024)
  string(STRIP "${HEAD_HASH}" HEAD_HASH)
endif()
