cmake_minimum_required(VERSION 3.22...3.23)
project(Halide_Python)

include(CMakeDependentOption)

##
# Project options
##

# Preferred defaults for built-in options
set(CMAKE_CXX_STANDARD 17 CACHE STRING "The minimum C++ standard to use")
option(CMAKE_CXX_STANDARD_REQUIRED "Prevent CMake C++ standard selection decay" ON)
option(CMAKE_CXX_EXTENSIONS "Enable C++ vendor extensions (e.g. GNU)" OFF)

# Duplicated options from parent project
option(WITH_TESTS "Build tests" ON)
option(WITH_TUTORIALS "Build tutorials" ON)
option(WITH_PYTHON_STUBS "Build Python stubs" ON)

# Enable/disable testing
cmake_dependent_option(
    WITH_TEST_PYTHON "Build Python tests" ON
    WITH_TESTS OFF
)

# Set the expected (downloaded) version of pybind11
option(PYBIND11_USE_FETCHCONTENT "Enable to download pybind11 via FetchContent" ON)
set(PYBIND11_VER 2.6.2 CACHE STRING "The pybind11 version to use (or download)")

##
# Dependencies
##

# The plain Development component is the same as requesting both
# Development.Module and Development.Embed. We don't need the Embed
# part, so only requesting Module avoids failures when Embed is not
# available, as is the case in the manylinux Docker images.
find_package(Python3 REQUIRED COMPONENTS Interpreter Development.Module)
if (Python3_VERSION VERSION_LESS "3.8")
    message(FATAL_ERROR "Halide requires Python v3.8 or later, but found ${Python3_VERSION}.")
endif ()
message(STATUS "Found Python ${Python3_VERSION} at ${Python3_EXECUTABLE}")

if (PYBIND11_USE_FETCHCONTENT)
    include(FetchContent)
    FetchContent_Declare(
        pybind11
        GIT_REPOSITORY https://github.com/pybind/pybind11.git
        GIT_TAG v${PYBIND11_VER}
    )
    FetchContent_MakeAvailable(pybind11)
else ()
    find_package(pybind11 ${PYBIND11_VER} REQUIRED)
endif ()

find_package(Halide REQUIRED Halide)
if (NOT Halide_ENABLE_RTTI OR NOT Halide_ENABLE_EXCEPTIONS)
    message(FATAL_ERROR "Python bindings require RTTI and exceptions to be enabled.")
endif ()

##
# A helper for creating tests with correct PYTHONPATH and sanitizer preloading
##

if (Halide_ASAN_ENABLED)
    if (NOT DEFINED Halide_Python_ASAN_LIBRARY)
        # TODO: this assumes clang-on-Linux, we could be smarter here and check
        #   CMAKE_CXX_COMPILER_ID to behave differently on GNU, AppleClang, or
        #   MSVC.
        execute_process(
            COMMAND ${CMAKE_CXX_COMPILER} "-print-file-name=libclang_rt.asan.so"
            OUTPUT_VARIABLE Halide_Python_ASAN_LIBRARY
            OUTPUT_STRIP_TRAILING_WHITESPACE
        )
    endif ()

    set(Halide_Python_ASAN_LIBRARY "${Halide_Python_ASAN_LIBRARY}"
        CACHE FILEPATH "Library to preload when running Python tests.")
endif ()

function(add_python_test)
    cmake_parse_arguments(ARG "" "FILE;LABEL" "PYTHONPATH;ENVIRONMENT;TEST_ARGS" ${ARGN})

    list(PREPEND ARG_PYTHONPATH "$<TARGET_FILE_DIR:Halide::Python>/..")
    list(TRANSFORM ARG_PYTHONPATH PREPEND "PYTHONPATH=path_list_prepend:")

    list(PREPEND ARG_ENVIRONMENT "HL_TARGET=${Halide_TARGET}")
    if (Halide_Python_ASAN_LIBRARY)
        if (APPLE)
            list(PREPEND ARG_ENVIRONMENT "DYLD_INSERT_LIBRARIES=${Halide_Python_ASAN_LIBRARY}")
        else ()
            list(PREPEND ARG_ENVIRONMENT "LD_PRELOAD=${Halide_Python_ASAN_LIBRARY}")
        endif ()
    endif ()

    cmake_path(GET ARG_FILE STEM test_name)
    set(test_name "${ARG_LABEL}_${test_name}")

    add_test(
        NAME "${test_name}"
        COMMAND Python3::Interpreter "$<SHELL_PATH:${CMAKE_CURRENT_SOURCE_DIR}/${ARG_FILE}>" ${ARG_TEST_ARGS}
    )
    set_tests_properties(
        "${test_name}"
        PROPERTIES
        LABELS "python"
        ENVIRONMENT "${ARG_ENVIRONMENT}"
        ENVIRONMENT_MODIFICATION "${ARG_PYTHONPATH}"
    )
endfunction()


##
# Add our sources to this sub-tree.
##

add_subdirectory(src)

if (WITH_PYTHON_STUBS)
    add_subdirectory(stub)
endif ()

if (WITH_TEST_PYTHON)
    add_subdirectory(apps)
    add_subdirectory(test)
endif ()

if (WITH_TUTORIALS)
    add_subdirectory(tutorial)
endif ()