# - 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(<refvar> <hashvar> [<additional arguments to git describe> ...])
#
# Returns the ref 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.
#
# 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
# https://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)

find_package(Git QUIET)

function(get_git_head_revision _refvar _hashvar)
  if(NOT GIT_EXECUTABLE)
    set(${_refvar}
        "GIT-NOTFOUND"
        PARENT_SCOPE)
    set(${_hashvar}
        "GIT-NOTFOUND"
        PARENT_SCOPE)
    return()
  endif()

  set(src_dir ${PROJECT_SOURCE_DIR})
  set(bin_dir ${PROJECT_BINARY_DIR})

  execute_process(
    COMMAND ${GIT_EXECUTABLE} rev-parse --git-dir
    WORKING_DIRECTORY ${src_dir}
    OUTPUT_VARIABLE GIT_DIR
    ERROR_VARIABLE error
    RESULT_VARIABLE failed
    OUTPUT_STRIP_TRAILING_WHITESPACE)

  if(NOT IS_ABSOLUTE "${GIT_DIR}")
    set(GIT_DIR "${src_dir}/${GIT_DIR}")
  endif()
  if(failed OR NOT EXISTS "${GIT_DIR}/HEAD")
    # not in git
    set(${_refvar}
        "GITDIR-NOTFOUND"
        PARENT_SCOPE)
    set(${_hashvar}
        "GITDIR-NOTFOUND"
        PARENT_SCOPE)
    return()
  endif()
  set(GIT_DATA "${bin_dir}/CMakeFiles/git-data")
  if(NOT EXISTS "${GIT_DATA}")
    file(MAKE_DIRECTORY "${GIT_DATA}")
  endif()
  configure_file("${GIT_DIR}/HEAD" "${GIT_DATA}/HEAD" COPYONLY)

  file(
    STRINGS "${GIT_DIR}/HEAD" head
    LIMIT_COUNT 1
    LIMIT_INPUT 1024)
  if("${head}" MATCHES "^ref: (.*)$")
    set(HEAD_REF "${CMAKE_MATCH_1}")
    if(EXISTS "${GIT_DIR}/${HEAD_REF}")
      configure_file("${GIT_DIR}/${HEAD_REF}" "${GIT_DATA}/HEAD-REF" COPYONLY)
    endif()
  else()
    set(HEAD_REF "")
  endif()
  execute_process(
    COMMAND ${GIT_EXECUTABLE} rev-parse HEAD
    WORKING_DIRECTORY ${src_dir}
    OUTPUT_VARIABLE HEAD_HASH
    OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_VARIABLE error
    RESULT_VARIABLE failed)
  if(failed)
    set(HEAD_HASH "HEAD-HASH-NOTFOUND")
  endif()
  set(${_refvar}
      "${HEAD_REF}"
      PARENT_SCOPE)
  set(${_hashvar}
      "${HEAD_HASH}"
      PARENT_SCOPE)
endfunction()

# get the number of commits since the file has last been modified
function(git_commits_since file _commits)
  get_git_head_revision(ref head)

  set(src_dir ${PROJECT_SOURCE_DIR})

  execute_process(
    COMMAND ${GIT_EXECUTABLE} rev-list ${head} -n 1 -- ${file}
    WORKING_DIRECTORY ${src_dir}
    OUTPUT_VARIABLE tag
    OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_VARIABLE error
    RESULT_VARIABLE failed)
  if(failed)
    set(tag "")
  endif()

  execute_process(
    COMMAND ${GIT_EXECUTABLE} rev-list ${tag}..${head}
    WORKING_DIRECTORY ${src_dir}
    OUTPUT_VARIABLE rev_list
    OUTPUT_STRIP_TRAILING_WHITESPACE
    ERROR_VARIABLE error
    RESULT_VARIABLE failed)

  if(failed)
    set(rev_list "")
  endif()

  string(
    REGEX MATCHALL
          "[a-fA-F0-9]+"
          rev_list
          "${rev_list}")
  list(LENGTH rev_list COUNT)

  set(${_commits}
      "${COUNT}"
      PARENT_SCOPE)
endfunction()

function(git_describe _var)
  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()

  set(src_dir ${PROJECT_SOURCE_DIR})

  # TODO sanitize
  #if((${ARGN}" MATCHES "&&") OR
  #    (ARGN MATCHES "||") OR
  #    (ARGN MATCHES "\\;"))
  #    message("Please report the following error to the project!")
  #    message(FATAL_ERROR "Looks like someone's doing something nefarious with git_describe! Passed arguments ${ARGN}")
  #endif()

  #message(STATUS "Arguments to execute_process: ${ARGN}")

  execute_process(
    COMMAND "${GIT_EXECUTABLE}" describe ${hash} ${ARGN}
    WORKING_DIRECTORY "${src_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_head_date _var)
  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()

  set(src_dir ${PROJECT_SOURCE_DIR})
  execute_process(
    COMMAND "${GIT_EXECUTABLE}" show -s --format=%ci ${hash} ${ARGN}
    WORKING_DIRECTORY "${src_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_head_date _var)
  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()

  set(src_dir ${PROJECT_SOURCE_DIR})
  execute_process(
    COMMAND "${GIT_EXECUTABLE}" show -s --format=%ci ${hash} ${ARGN}
    WORKING_DIRECTORY "${src_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_head_localmods _var)
  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()

  set(src_dir ${PROJECT_SOURCE_DIR})
  ## Determine if there are local modifications to the HEAD
  execute_process(
    COMMAND ${GIT_EXECUTABLE} diff --shortstat HEAD
    WORKING_DIRECTORY ${src_dir}
    RESULT_VARIABLE res
    OUTPUT_VARIABLE out
    ERROR_VARIABLE error
    OUTPUT_STRIP_TRAILING_WHITESPACE)
  if(NOT
     res
     EQUAL
     0)
    set(out "${out}-${res}-NOTFOUND")
  endif()
  set(${_var}
      "${out}"
      PARENT_SCOPE)
endfunction()