# Cable: CMake Bootstrap Library.
# Copyright 2018 Pawel Bylica.
# Licensed under the Apache License, Version 2.0. See the LICENSE file.

# Execute git only if the tool is available.
if(GIT)
    execute_process(
        COMMAND ${GIT} describe --always --long --tags --match=v* --abbrev=40 --dirty
        WORKING_DIRECTORY ${SOURCE_DIR}
        OUTPUT_VARIABLE gitinfo
        OUTPUT_STRIP_TRAILING_WHITESPACE
        ERROR_VARIABLE error
        ERROR_STRIP_TRAILING_WHITESPACE
    )
endif()

if(error)
    message(WARNING "Git ${error}")
endif()

set(gitinfo_file ${OUTPUT_DIR}/gitinfo.txt)

if(EXISTS ${gitinfo_file})
    file(READ ${gitinfo_file} prev_gitinfo)
else()
    # Create empty file, because other targets expect it to exist.
    file(WRITE ${gitinfo_file} "")
endif()

if(NOT "${gitinfo}" STREQUAL "${prev_gitinfo}")
    file(WRITE ${gitinfo_file} ${gitinfo})
endif()