# Get the current commit ref
if(NOT GIT_DESCRIBE)
  execute_process(
    COMMAND git describe --tags --always --first-parent --dirty=-modified
    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
    OUTPUT_VARIABLE GIT_DESCRIBE
    OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_QUIET
  )
  if(NOT GIT_DESCRIBE)
    message(NOTICE "Git describe is unknown, you may set it via GIT_DESCRIBE")
  else()
    message(NOTICE "Git describe: ${GIT_DESCRIBE}")
    string(REGEX MATCH "-modified$" GIT_DIRTY "${GIT_DESCRIBE}")
    if(GIT_DIRTY)
      message("Git worktree modified: yes")
      set(GIT_DIRTY 1)
    else()
      message(NOTICE "Git worktree modified: no")
      set(GIT_DIRTY 0)
    endif()

    # Get the current working branch
    execute_process(
      COMMAND git rev-parse --abbrev-ref HEAD
      WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
      OUTPUT_VARIABLE GIT_BRANCH
      OUTPUT_STRIP_TRAILING_WHITESPACE
      ERROR_QUIET
    )
    if(NOT GIT_BRANCH)
      message(NOTICE "Git branch: unknown")
    else()
      message(NOTICE "Git branch: ${GIT_BRANCH}")
    endif()
    # Get the number of commits since the version tag
    string(
      REGEX MATCH
      ".*-([0-9]*)-.*"
      GIT_COMMIT_COUNT_MATCH
      "${GIT_DESCRIBE}"
    )
    if(GIT_COMMIT_COUNT_MATCH)
      set(GIT_COMMIT_COUNT "${CMAKE_MATCH_1}")
      message(NOTICE "Git commit count: ${GIT_COMMIT_COUNT}")
    else()
      message(NOTICE "Git commit count: unknown")
    endif()
  endif()
else()
  message(NOTICE "Git describe: ${GIT_DESCRIBE}")
  if(NOT GIT_COMMIT_DATE)
    message(
      NOTICE
      "Git commit date unknown, using current time for GIT_COMMIT_DATE"
    )
    # use current date in case of tar ball builds
    string(TIMESTAMP GIT_COMMIT_DATE "%Y-%m-%dT%H:%M:%SZ" UTC)
  endif()
endif()

# Get the current commit date
if(NOT GIT_COMMIT_DATE)
  execute_process(
    COMMAND git show --quiet --format=%cI --date=short --no-show-signature
    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
    OUTPUT_VARIABLE GIT_COMMIT_DATE
    OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_QUIET
  )
endif()

if(NOT GIT_COMMIT_DATE)
  message(
    NOTICE
    "Git commit date unknown, using current time for GIT_COMMIT_DATE"
  )
  # use current date in case of tar ball builds
  string(TIMESTAMP GIT_COMMIT_DATE "%Y-%m-%dT%H:%M:%SZ" UTC)
else()
  message(NOTICE "Git commit date: ${GIT_COMMIT_DATE}")
endif()
string(REGEX MATCH "^[0-9][0-9][0-9][0-9]" GIT_COMMIT_YEAR "${GIT_COMMIT_DATE}")