# If the cmake variable "PYTHON_DEVELOPMENT_REQUIRED" is set to ON
# then the development environments are found.

# CMake will use FindPython3 and can be controlled accordingly (i.e. setting Python3_ROOT_DIR or
# Python3_FIND_REGISTRY (useful if using PATH to specify Python3 version on Windows).
# Additionally, setting Python3_EXECUTABLE can be used to set the Python version explicitly, but
# may become less reliable with newer versions of CMake (as opposed setting FindPython3 HINTS).  Current
# implementation gives preference to active virtualenvs.

cmake_policy(SET CMP0094 NEW) # makes FindPython3 prefer activated virtualenv Python to latest version
set(PYTHON_VERSION_MIN 3.9)
set(PYTHON_VERSION_MAX 3.999)

if(PYTHON_DEVELOPMENT_REQUIRED)
  if(DEFINED Python3_EXECUTABLE) # if already specified
    set(_specified_Python3_EXECUTABLE ${Python3_EXECUTABLE})
  endif()
  # set(Python3_FIND_REGISTRY LAST) # default is FIRST. Do we need/want this?
  find_package(
    Python3
    ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX}
    COMPONENTS
      Interpreter
      Development.Module
      ${SKBUILD_SABI_COMPONENT}
  )
  if(DEFINED _specified_Python3_EXECUTABLE)
    set(
      Python3_EXECUTABLE
      ${_specified_Python3_EXECUTABLE}
      CACHE INTERNAL
      "Path to the Python interpreter"
      FORCE
    )
  endif()
else() # if not PYTHON_DEVELOPMENT_REQUIRED, just find some version of Python (don't need to be as specific)
  find_package(
    Python3
    ${PYTHON_VERSION_MIN}...${PYTHON_VERSION_MAX}
    COMPONENTS
      Interpreter
  )
endif()
if(ITK_WRAP_PYTHON)
  set(ITK_WRAP_PYTHON_VERSION "${Python3_VERSION}")
else()
  set(ITK_WRAP_PYTHON_VERSION "ITK_WRAP_PYTHON=OFF")
endif()
if(NOT Python3_EXECUTABLE AND _specified_Python3_EXECUTABLE) # workaround for cases where FindPython3 fails to set correctly
  set(
    Python3_EXECUTABLE
    ${_specified_Python3_EXECUTABLE}
    CACHE INTERNAL
    "Path to the Python interpreter"
    FORCE
  )
endif()

# Add user-visible cache entry
set(
  Python3_ROOT_DIR
  ${Python3_ROOT_DIR}
  CACHE PATH
  "Which installation or virtual environment of Python to use"
  FORCE
)
mark_as_advanced(Python3_ROOT_DIR)