"Manages CMake."

from __future__ import annotations

import multiprocessing
import os
import platform
import sys
import sysconfig
from distutils.version import LooseVersion
from subprocess import CalledProcessError, check_call, check_output
from typing import Any, cast

from . import which
from .cmake_utils import CMakeValue, get_cmake_cache_variables_from_file
from .env import BUILD_DIR, check_negative_env_flag, IS_64BIT, IS_DARWIN, IS_WINDOWS


def _mkdir_p(d: str) -> None:
    try:
        os.makedirs(d, exist_ok=True)
    except OSError as e:
        raise RuntimeError(
            f"Failed to create folder {os.path.abspath(d)}: {e.strerror}"
        ) from e


# Ninja
# Use ninja if it is on the PATH. Previous version of PyTorch required the
# ninja python package, but we no longer use it, so we do not have to import it
USE_NINJA = not check_negative_env_flag("USE_NINJA") and which("ninja") is not None
if "CMAKE_GENERATOR" in os.environ:
    USE_NINJA = os.environ["CMAKE_GENERATOR"].lower() == "ninja"


class CMake:
    "Manages cmake."

    def __init__(self, build_dir: str = BUILD_DIR) -> None:
        self._cmake_command = CMake._get_cmake_command()
        self.build_dir = build_dir

    @property
    def _cmake_cache_file(self) -> str:
        r"""Returns the path to CMakeCache.txt.

        Returns:
          string: The path to CMakeCache.txt.
        """
        return os.path.join(self.build_dir, "CMakeCache.txt")

    @staticmethod
    def _get_cmake_command() -> str:
        "Returns cmake command."

        cmake_command = "cmake"
        if IS_WINDOWS:
            return cmake_command
        cmake3_version = CMake._get_version(which("cmake3"))
        cmake_version = CMake._get_version(which("cmake"))

        _cmake_min_version = LooseVersion("3.18.0")
        if all(
            ver is None or ver < _cmake_min_version
            for ver in [cmake_version, cmake3_version]
        ):
            raise RuntimeError("no cmake or cmake3 with version >= 3.18.0 found")

        if cmake3_version is None:
            cmake_command = "cmake"
        elif cmake_version is None:
            cmake_command = "cmake3"
        else:
            if cmake3_version >= cmake_version:
                cmake_command = "cmake3"
            else:
                cmake_command = "cmake"
        return cmake_command

    @staticmethod
    def _get_version(cmd: str | None) -> Any:
        "Returns cmake version."

        if cmd is None:
            return None
        for line in check_output([cmd, "--version"]).decode("utf-8").split("\n"):
            if "version" in line:
                return LooseVersion(line.strip().split(" ")[2])
        raise RuntimeError("no version found")

    def run(self, args: list[str], env: dict[str, str]) -> None:
        "Executes cmake with arguments and an environment."

        command = [self._cmake_command] + args
        print(" ".join(command))
        try:
            check_call(command, cwd=self.build_dir, env=env)
        except (CalledProcessError, KeyboardInterrupt):
            # This error indicates that there was a problem with cmake, the
            # Python backtrace adds no signal here so skip over it by catching
            # the error and exiting manually
            sys.exit(1)

    @staticmethod
    def defines(args: list[str], **kwargs: CMakeValue) -> None:
        "Adds definitions to a cmake argument list."
        for key, value in sorted(kwargs.items()):
            if value is not None:
                args.append(f"-D{key}={value}")

    def get_cmake_cache_variables(self) -> dict[str, CMakeValue]:
        r"""Gets values in CMakeCache.txt into a dictionary.
        Returns:
          dict: A ``dict`` containing the value of cached CMake variables.
        """
        with open(self._cmake_cache_file) as f:
            return get_cmake_cache_variables_from_file(f)

    def generate(
        self,
        version: str | None,
        cmake_python_library: str | None,
        build_python: bool,
        build_test: bool,
        my_env: dict[str, str],
        rerun: bool,
    ) -> None:
        "Runs cmake to generate native build files."

        if rerun and os.path.isfile(self._cmake_cache_file):
            os.remove(self._cmake_cache_file)

        ninja_build_file = os.path.join(self.build_dir, "build.ninja")
        if os.path.exists(self._cmake_cache_file) and not (
            USE_NINJA and not os.path.exists(ninja_build_file)
        ):
            # Everything's in place. Do not rerun.
            return

        args = []
        if USE_NINJA:
            # Avoid conflicts in '-G' and the `CMAKE_GENERATOR`
            os.environ["CMAKE_GENERATOR"] = "Ninja"
            args.append("-GNinja")
        elif IS_WINDOWS:
            generator = os.getenv("CMAKE_GENERATOR", "Visual Studio 16 2019")
            supported = ["Visual Studio 16 2019", "Visual Studio 17 2022"]
            if generator not in supported:
                print("Unsupported `CMAKE_GENERATOR`: " + generator)
                print("Please set it to one of the following values: ")
                print("\n".join(supported))
                sys.exit(1)
            args.append("-G" + generator)
            toolset_dict = {}
            toolset_version = os.getenv("CMAKE_GENERATOR_TOOLSET_VERSION")
            if toolset_version is not None:
                toolset_dict["version"] = toolset_version
                curr_toolset = os.getenv("VCToolsVersion")
                if curr_toolset is None:
                    print(
                        "When you specify `CMAKE_GENERATOR_TOOLSET_VERSION`, you must also "
                        "activate the vs environment of this version. Please read the notes "
                        "in the build steps carefully."
                    )
                    sys.exit(1)
            if IS_64BIT:
                if platform.machine() == "ARM64":
                    args.append("-A ARM64")
                else:
                    args.append("-Ax64")
                    toolset_dict["host"] = "x64"
            if toolset_dict:
                toolset_expr = ",".join([f"{k}={v}" for k, v in toolset_dict.items()])
                args.append("-T" + toolset_expr)

        base_dir = os.path.dirname(
            os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
        )
        install_dir = os.path.join(base_dir, "torch")

        _mkdir_p(install_dir)
        _mkdir_p(self.build_dir)

        # Store build options that are directly stored in environment variables
        build_options: dict[str, CMakeValue] = {}

        # Build options that do not start with "BUILD_", "USE_", or "CMAKE_" and are directly controlled by env vars.
        # This is a dict that maps environment variables to the corresponding variable name in CMake.
        additional_options = {
            # Key: environment variable name. Value: Corresponding variable name to be passed to CMake. If you are
            # adding a new build option to this block: Consider making these two names identical and adding this option
            # in the block below.
            "_GLIBCXX_USE_CXX11_ABI": "GLIBCXX_USE_CXX11_ABI",
            "CUDNN_LIB_DIR": "CUDNN_LIBRARY",
            "USE_CUDA_STATIC_LINK": "CAFFE2_STATIC_LINK_CUDA",
        }
        additional_options.update(
            {
                # Build options that have the same environment variable name and CMake variable name and that do not start
                # with "BUILD_", "USE_", or "CMAKE_". If you are adding a new build option, also make sure you add it to
                # CMakeLists.txt.
                var: var
                for var in (
                    "UBSAN_FLAGS",
                    "BLAS",
                    "WITH_BLAS",
                    "CUDA_HOST_COMPILER",
                    "CUDA_NVCC_EXECUTABLE",
                    "CUDA_SEPARABLE_COMPILATION",
                    "CUDNN_LIBRARY",
                    "CUDNN_INCLUDE_DIR",
                    "CUDNN_ROOT",
                    "EXPERIMENTAL_SINGLE_THREAD_POOL",
                    "INSTALL_TEST",
                    "JAVA_HOME",
                    "INTEL_MKL_DIR",
                    "INTEL_OMP_DIR",
                    "MKL_THREADING",
                    "MKLDNN_CPU_RUNTIME",
                    "MSVC_Z7_OVERRIDE",
                    "CAFFE2_USE_MSVC_STATIC_RUNTIME",
                    "Numa_INCLUDE_DIR",
                    "Numa_LIBRARIES",
                    "ONNX_ML",
                    "ONNX_NAMESPACE",
                    "ATEN_THREADING",
                    "WERROR",
                    "OPENSSL_ROOT_DIR",
                    "STATIC_DISPATCH_BACKEND",
                    "SELECTED_OP_LIST",
                    "TORCH_CUDA_ARCH_LIST",
                    "TORCH_XPU_ARCH_LIST",
                    "TRACING_BASED",
                    "PYTHON_LIB_REL_PATH",
                )
            }
        )

        # Aliases which are lower priority than their canonical option
        low_priority_aliases = {
            "CUDA_HOST_COMPILER": "CMAKE_CUDA_HOST_COMPILER",
            "CUDAHOSTCXX": "CUDA_HOST_COMPILER",
            "CMAKE_CUDA_HOST_COMPILER": "CUDA_HOST_COMPILER",
            "CMAKE_CUDA_COMPILER": "CUDA_NVCC_EXECUTABLE",
            "CUDACXX": "CUDA_NVCC_EXECUTABLE",
        }
        for var, val in my_env.items():
            # We currently pass over all environment variables that start with "BUILD_", "USE_", and "CMAKE_". This is
            # because we currently have no reliable way to get the list of all build options we have specified in
            # CMakeLists.txt. (`cmake -L` won't print dependent options when the dependency condition is not met.) We
            # will possibly change this in the future by parsing CMakeLists.txt ourselves (then additional_options would
            # also not be needed to be specified here).
            true_var = additional_options.get(var)
            if true_var is not None:
                build_options[true_var] = val
            elif var.startswith(("BUILD_", "USE_", "CMAKE_")) or var.endswith(
                ("EXITCODE", "EXITCODE__TRYRUN_OUTPUT")
            ):
                build_options[var] = val

            if var in low_priority_aliases:
                key = low_priority_aliases[var]
                if key not in build_options:
                    build_options[key] = val

        # The default value cannot be easily obtained in CMakeLists.txt. We set it here.
        py_lib_path = sysconfig.get_path("purelib")
        cmake_prefix_path = build_options.get("CMAKE_PREFIX_PATH", None)
        if cmake_prefix_path:
            build_options["CMAKE_PREFIX_PATH"] = (
                py_lib_path + ";" + cast(str, cmake_prefix_path)
            )
        else:
            build_options["CMAKE_PREFIX_PATH"] = py_lib_path

        # Some options must be post-processed. Ideally, this list will be shrunk to only one or two options in the
        # future, as CMake can detect many of these libraries pretty comfortably. We have them here for now before CMake
        # integration is completed. They appear here not in the CMake.defines call below because they start with either
        # "BUILD_" or "USE_" and must be overwritten here.
        build_options.update(
            {
                # Note: Do not add new build options to this dict if it is directly read from environment variable -- you
                # only need to add one in `CMakeLists.txt`. All build options that start with "BUILD_", "USE_", or "CMAKE_"
                # are automatically passed to CMake; For other options you can add to additional_options above.
                "BUILD_PYTHON": build_python,
                "BUILD_TEST": build_test,
                # Most library detection should go to CMake script, except this one, which Python can do a much better job
                # due to NumPy's inherent Pythonic nature.
                "USE_NUMPY": not check_negative_env_flag("USE_NUMPY"),
            }
        )

        # Options starting with CMAKE_
        cmake__options = {
            "CMAKE_INSTALL_PREFIX": install_dir,
        }

        # We set some CMAKE_* options in our Python build code instead of relying on the user's direct settings. Emit an
        # error if the user also attempts to set these CMAKE options directly.
        specified_cmake__options = set(build_options).intersection(cmake__options)
        if len(specified_cmake__options) > 0:
            print(
                ", ".join(specified_cmake__options)
                + " should not be specified in the environment variable. They are directly set by PyTorch build script."
            )
            sys.exit(1)
        build_options.update(cmake__options)

        CMake.defines(
            args,
            Python_EXECUTABLE=sys.executable,
            TORCH_BUILD_VERSION=version,
            **build_options,
        )

        expected_wrapper = "/usr/local/opt/ccache/libexec"
        if IS_DARWIN and os.path.exists(expected_wrapper):
            if "CMAKE_C_COMPILER" not in build_options and "CC" not in os.environ:
                CMake.defines(args, CMAKE_C_COMPILER=f"{expected_wrapper}/gcc")
            if "CMAKE_CXX_COMPILER" not in build_options and "CXX" not in os.environ:
                CMake.defines(args, CMAKE_CXX_COMPILER=f"{expected_wrapper}/g++")

        for env_var_name in my_env:
            if env_var_name.startswith("gh"):
                # github env vars use utf-8, on windows, non-ascii code may
                # cause problem, so encode first
                try:
                    my_env[env_var_name] = str(my_env[env_var_name].encode("utf-8"))
                except UnicodeDecodeError as e:
                    shex = ":".join(f"{ord(c):02x}" for c in my_env[env_var_name])
                    print(
                        f"Invalid ENV[{env_var_name}] = {shex}",
                        file=sys.stderr,
                    )
                    print(e, file=sys.stderr)
        # According to the CMake manual, we should pass the arguments first,
        # and put the directory as the last element. Otherwise, these flags
        # may not be passed correctly.
        # Reference:
        # 1. https://cmake.org/cmake/help/latest/manual/cmake.1.html#synopsis
        # 2. https://stackoverflow.com/a/27169347
        args.append(base_dir)
        self.run(args, env=my_env)

    def build(self, my_env: dict[str, str]) -> None:
        "Runs cmake to build binaries."

        from .env import build_type

        build_args = [
            "--build",
            ".",
            "--target",
            "install",
            "--config",
            build_type.build_type_string,
        ]

        # Determine the parallelism according to the following
        # priorities:
        # 1) MAX_JOBS environment variable
        # 2) If using the Ninja build system, delegate decision to it.
        # 3) Otherwise, fall back to the number of processors.

        # Allow the user to set parallelism explicitly. If unset,
        # we'll try to figure it out.
        max_jobs = os.getenv("MAX_JOBS")

        if max_jobs is not None or not USE_NINJA:
            # Ninja is capable of figuring out the parallelism on its
            # own: only specify it explicitly if we are not using
            # Ninja.

            # This lists the number of processors available on the
            # machine. This may be an overestimate of the usable
            # processors if CPU scheduling affinity limits it
            # further. In the future, we should check for that with
            # os.sched_getaffinity(0) on platforms that support it.
            max_jobs = max_jobs or str(multiprocessing.cpu_count())

            # This ``if-else'' clause would be unnecessary when cmake
            # 3.12 becomes minimum, which provides a '-j' option:
            # build_args += ['-j', max_jobs] would be sufficient by
            # then. Until then, we use "--" to pass parameters to the
            # underlying build system.
            build_args += ["--"]
            if IS_WINDOWS and not USE_NINJA:
                # We are likely using msbuild here
                build_args += [f"/p:CL_MPCount={max_jobs}"]
            else:
                build_args += ["-j", max_jobs, '-v']
        self.run(build_args, my_env)