# * 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(<var> [<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(<var> [<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.
#
# git_local_changes(<var>)
#
# Returns either "CLEAN" or "DIRTY" with respect to uncommitted changes. Uses the return code of "git diff-index --quiet
# HEAD --". Does not regard untracked files.
#
# 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 "${CMAKE_CURRENT_SOURCE_DIR}")
  set(GIT_DIR "${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()
  # check if this is a submodule
  if(NOT IS_DIRECTORY ${GIT_DIR})
    file(READ ${GIT_DIR} submodule)
    string(REGEX REPLACE "gitdir: (.*)\n$" "\\1" GIT_DIR_RELATIVE ${submodule})
    get_filename_component(SUBMODULE_DIR ${GIT_DIR} PATH)
    get_filename_component(GIT_DIR ${SUBMODULE_DIR}/${GIT_DIR_RELATIVE} ABSOLUTE)
  endif()
  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_get_latest_tag _var)
  if(NOT GIT_FOUND)
    find_package(Git QUIET)
  endif()

  # We use git describe --tags `git rev-list --exclude "*.*.*-*" --tags --max-count=1`
  # Note how we eclude prereleases tags (the ones with "-alphaX")
  execute_process(COMMAND
          "${GIT_EXECUTABLE}"
          rev-list
          --exclude "*.*.*-*"
          --tags
          --max-count=1
          WORKING_DIRECTORY
          "${CMAKE_CURRENT_SOURCE_DIR}"
          RESULT_VARIABLE
          res
          OUTPUT_VARIABLE
          tag_hash
          ERROR_QUIET
          OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(out "${tag_hash}-${res}-NOTFOUND" PARENT_SCOPE)
    return()
  endif()

  execute_process(COMMAND
    "${GIT_EXECUTABLE}"
    describe
    --tags
    ${tag_hash}
    WORKING_DIRECTORY
    "${CMAKE_CURRENT_SOURCE_DIR}"
    RESULT_VARIABLE
    res
    OUTPUT_VARIABLE
    out
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(out "${out}-${res}-NOTFOUND")
  endif()
  set(${_var} "${out}" PARENT_SCOPE)
endfunction()

function(git_get_delta_from_tag _var tag hash)
  if(NOT GIT_FOUND)
    find_package(Git QUIET)
  endif()

  # Count commits in HEAD
  execute_process(COMMAND
    "${GIT_EXECUTABLE}"
    rev-list
    --count
    ${hash}
    WORKING_DIRECTORY
    "${CMAKE_CURRENT_SOURCE_DIR}"
    RESULT_VARIABLE
    res
    OUTPUT_VARIABLE
    out_counter_head
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(${_var} "HEADCOUNT-NOTFOUND" PARENT_SCOPE)
    return()
  endif()

  # Count commits in latest tag
  execute_process(COMMAND
    "${GIT_EXECUTABLE}"
    rev-list
    --count
    ${tag}
    WORKING_DIRECTORY
    "${CMAKE_CURRENT_SOURCE_DIR}"
    RESULT_VARIABLE
    res
    OUTPUT_VARIABLE
    out_counter_tag
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(${_var} "TAGCOUNT-NOTFOUND" PARENT_SCOPE)
    return()
  endif()

  execute_process(COMMAND
    expr
    ${out_counter_head} - ${out_counter_tag}
    WORKING_DIRECTORY
    "${CMAKE_CURRENT_SOURCE_DIR}"
    RESULT_VARIABLE
    res
    OUTPUT_VARIABLE
    out_delta
    ERROR_QUIET
    OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(${_var} "DELTA-NOTFOUND" PARENT_SCOPE)
    return()
  endif()
  set(${_var} "${out_delta}" PARENT_SCOPE)
endfunction()

function(git_describe _var)
  if(NOT GIT_FOUND)
    find_package(Git QUIET)
  endif()
  get_git_head_revision(refspec hash)
  if(NOT GIT_FOUND)
    set(${_var}
            "GIT-NOTFOUND"
            PARENT_SCOPE)
    return()
  endif()
  if(NOT hash)
    set(${_var}
            "HEAD-HASH-NOTFOUND"
            PARENT_SCOPE)
    return()
  endif()

  execute_process(COMMAND
          "${GIT_EXECUTABLE}"
          describe
          ${hash}
          ${ARGN}
          WORKING_DIRECTORY
          "${CMAKE_CURRENT_SOURCE_DIR}"
          RESULT_VARIABLE
          res
          OUTPUT_VARIABLE
          out
          ERROR_QUIET
          OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT res EQUAL 0)
    set(out "${out}-${res}-NOTFOUND")
  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()

function(git_local_changes _var)
  if(NOT GIT_FOUND)
    find_package(Git QUIET)
  endif()
  get_git_head_revision(refspec hash)
  if(NOT GIT_FOUND)
    set(${_var}
        "GIT-NOTFOUND"
        PARENT_SCOPE)
    return()
  endif()
  if(NOT hash)
    set(${_var}
        "HEAD-HASH-NOTFOUND"
        PARENT_SCOPE)
    return()
  endif()

  execute_process(
    COMMAND "${GIT_EXECUTABLE}" diff-index --quiet HEAD --
    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
    RESULT_VARIABLE res
    OUTPUT_VARIABLE out
    ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(res EQUAL 0)
    set(${_var}
        "CLEAN"
        PARENT_SCOPE)
  else()
    set(${_var}
        "DIRTY"
        PARENT_SCOPE)
  endif()
endfunction()