# - Returns a version string from Git

#

# These functions force a re-configure on each git commit so that you can

# trust the values of the variables in your build system.

#

#  get_git_head_revision(<refspecvar> <hashvar> [<additional arguments to git describe> ...])

#

# Returns the refspec and sha hash of the current head revision

#

#  git_describe( [<additional arguments to git describe> ...])

#

# Returns the results of git describe on the source tree, and adjusting

# the output so that it tests false if an error occurs.

#

#  git_get_exact_tag( [<additional arguments to git describe> ...])

#

# Returns the results of git describe --exact-match on the source tree,

# and adjusting the output so that it tests false if there was no exact

# matching tag.

#

# 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 Iowa State University 2009-2010.

# 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)

if(__get_git_revision_description)

	return()

endif()

set(__get_git_revision_description YES)

# We must run the following at "include" time, not at function call time,

# to find the path to this module rather than the path to a calling list file

get_filename_component(_gitdescmoddir ${CMAKE_CURRENT_LIST_FILE} PATH)

function(get_git_head_revision _refspecvar _hashvar)

	set(GIT_PARENT_DIR "${CMAKE_SOURCE_DIR}")

	set(GIT_DIR "${GIT_PARENT_DIR}/.git")

	while(NOT EXISTS "${GIT_DIR}")	# .git dir not found, search parent directories

		set(GIT_PREVIOUS_PARENT "${GIT_PARENT_DIR}")

		get_filename_component(GIT_PARENT_DIR ${GIT_PARENT_DIR} PATH)

		if(GIT_PARENT_DIR STREQUAL GIT_PREVIOUS_PARENT)

			# We have reached the root directory, we are not in git

			set(${_refspecvar} "GITDIR-NOTFOUND" PARENT_SCOPE)

			set(${_hashvar} "GITDIR-NOTFOUND" PARENT_SCOPE)

			return()

		endif()

		set(GIT_DIR "${GIT_PARENT_DIR}/.git")

	endwhile()

	set(GIT_DATA "${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/git-data")

	if(NOT EXISTS "${GIT_DATA}")

		file(MAKE_DIRECTORY "${GIT_DATA}")

	endif()

	if(NOT EXISTS "${GIT_DIR}/HEAD")

		return()

	endif()

	set(HEAD_FILE "${GIT_DATA}/HEAD")

	configure_file("${GIT_DIR}/HEAD" "${HEAD_FILE}" COPYONLY)

	configure_file("${_gitdescmoddir}/GetGitRevisionDescription.cmake.in"

		"${GIT_DATA}/grabRef.cmake"

		@ONLY)

	include("${GIT_DATA}/grabRef.cmake")

	set(${_refspecvar} "${HEAD_REF}" PARENT_SCOPE)

	set(${_hashvar} "${HEAD_HASH}" PARENT_SCOPE)

endfunction()

function(git_rev_parse _var)

	if(NOT GIT_FOUND)

		find_package(Git QUIET)

	endif()

	if(NOT GIT_FOUND)

		set(${_var} "n/a" PARENT_SCOPE)

		return()

	endif()

	get_git_head_revision(refspec hash)

	if(NOT hash)

		set(${_var} "n/a" PARENT_SCOPE)

		return()

	endif()

	execute_process(COMMAND "${GIT_EXECUTABLE}" rev-parse ${ARGN} ${hash}

		WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"

		RESULT_VARIABLE res

		OUTPUT_VARIABLE out

		ERROR_QUIET

		OUTPUT_STRIP_TRAILING_WHITESPACE)

	if(NOT res EQUAL 0)

		set(out "n/a")

	endif()

	set(${_var} "${out}" PARENT_SCOPE)

endfunction()

function(git_describe _var)

	if(NOT GIT_FOUND)

		find_package(Git QUIET)

	endif()

	if(NOT GIT_FOUND)

		set(${_var} "n/a" PARENT_SCOPE)

		return()

	endif()

	get_git_head_revision(refspec hash)

	if(NOT hash)

		set(${_var} "n/a" PARENT_SCOPE)

		return()

	endif()

	execute_process(COMMAND "${GIT_EXECUTABLE}" describe ${hash} ${ARGN}

		WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"

		RESULT_VARIABLE res

		OUTPUT_VARIABLE out

		ERROR_QUIET

		OUTPUT_STRIP_TRAILING_WHITESPACE)

	if(NOT res EQUAL 0)

		set(out "n/a")

	endif()

	set(${_var} "${out}" PARENT_SCOPE)

endfunction()

function(git_get_exact_tag _var)

	git_describe(out --exact-match ${ARGN})

	set(${_var} "${out}" PARENT_SCOPE)

endfunction()