# Stamps GitInfo.cpp with the SHA of HEAD as it is NOW. Run with `cmake -P` on every build (see the
# JFJochGitInfo target in CMakeLists.txt here), so the hash a binary reports is the commit it was
# built from, not the one the tree held when it was last configured - a configure-time stamp once
# reported a hash seventeen commits stale. configure_file leaves the output untouched when nothing
# changed, so this costs a recompile only when HEAD moves. Also included at configure time, so the
# file exists for the generator and the SHA prints with the configure output.
# A source tree that is not a git checkout of its own - a downloaded tarball, perhaps unpacked inside
# some other repository - has no commit to report: the version from VERSION stands alone and the
# commit reads "unknown", and the build goes on.
SET(GIT_SHA1 "")
SET(GIT_DATE "")
if (GIT_EXECUTABLE)
    EXECUTE_PROCESS(COMMAND "${GIT_EXECUTABLE}" rev-parse --show-toplevel
            WORKING_DIRECTORY "${GITINFO_SOURCE_DIR}"
            OUTPUT_VARIABLE GIT_TOPLEVEL
            ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
    if (GIT_TOPLEVEL)
        FILE(REAL_PATH "${GIT_TOPLEVEL}" GIT_TOPLEVEL)
    endif ()
    FILE(REAL_PATH "${GITINFO_SOURCE_DIR}" GITINFO_SOURCE_REAL)
endif ()
if (GIT_EXECUTABLE AND GIT_TOPLEVEL STREQUAL GITINFO_SOURCE_REAL)
    # --dirty: a build from uncommitted changes says so in the hash itself
    EXECUTE_PROCESS(COMMAND
            "${GIT_EXECUTABLE}" describe --match=NeVeRmAtCh --always --abbrev=8 --dirty
            WORKING_DIRECTORY "${GITINFO_SOURCE_DIR}"
            OUTPUT_VARIABLE GIT_SHA1
            ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
    EXECUTE_PROCESS(COMMAND
            "${GIT_EXECUTABLE}" log -1 --format=%ad --date=local
            WORKING_DIRECTORY "${GITINFO_SOURCE_DIR}"
            OUTPUT_VARIABLE GIT_DATE
            ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
endif ()
if (NOT GIT_SHA1)
    SET(GIT_SHA1 "unknown")
endif ()
CONFIGURE_FILE("${GITINFO_TEMPLATE}" "${GITINFO_OUTPUT}" @ONLY)