# FindR.cmkae
# Make sure find package macros are included
set(TEMP_CMAKE_FIND_APPBUNDLE ${CMAKE_FIND_APPBUNDLE})
set(CMAKE_FIND_APPBUNDLE "NEVER")

# Find R.
find_program(R_EXECUTABLE R DOC "R executable.")

if(R_EXECUTABLE)
  # Get the location of R.
  execute_process(
      WORKING_DIRECTORY .
      COMMAND ${R_EXECUTABLE} RHOME
      OUTPUT_VARIABLE R_BASE_DIR
      OUTPUT_STRIP_TRAILING_WHITESPACE
  )

  # Get the R version.
  execute_process(
      COMMAND ${R_EXECUTABLE} --version
      OUTPUT_VARIABLE R_VERSION_STRING
      RESULT_VARIABLE RESULT
  )
  if (RESULT EQUAL 0)
    string(REGEX REPLACE ".*([0-9]+\\.[0-9]+\\.[0-9]+).*" "\\1"
        R_VERSION_STRING ${R_VERSION_STRING})
  endif ()

  set(R_HOME ${R_BASE_DIR} CACHE PATH "R home directory obtained from R RHOME")
  mark_as_advanced(R_HOME)
endif()

# Find the Rscript program.
find_program(RSCRIPT_EXECUTABLE Rscript DOC "Rscript executable.")

set(CMAKE_FIND_APPBUNDLE ${TEMP_CMAKE_FIND_APPBUNDLE})

mark_as_advanced(RSCRIPT_EXECUTABLE R_EXECUTABLE)
set( _REQUIRED_R_VARIABLES R_EXECUTABLE )

include( FindPackageHandleStandardArgs )
find_package_handle_standard_args(
    R
    REQUIRED_VARS ${_REQUIRED_R_VARIABLES}
    VERSION_VAR R_VERSION_STRING
    FAIL_MESSAGE "R not found"
)