# Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
#
# See LICENSE for license information.

"""FW agnostic user-end APIs"""

import ctypes
import functools
import glob
import importlib
from importlib.metadata import version, distribution, PackageNotFoundError
import os
from pathlib import Path
import platform
import subprocess
import sys
import sysconfig
from typing import Optional, Tuple


@functools.lru_cache(maxsize=None)
def _is_package_installed(package) -> bool:
    """Check if the given package is installed via pip."""

    # This is needed because we only want to return true
    # if the python package is installed via pip, and not
    # if it's importable in the current directory due to
    # the presence of the shared library module.
    try:
        distribution(package)
    except PackageNotFoundError:
        return False
    return True


@functools.lru_cache(maxsize=None)
def _is_package_installed_from_wheel(package) -> bool:
    """Check if the given package is installed via PyPI."""

    if not _is_package_installed(package):
        return False

    te_dist = distribution(package)
    te_wheel_file = ""
    for file_path in te_dist.files:
        if file_path.name == "WHEEL":
            te_wheel_file = te_dist.locate_file("") / file_path
    if not te_wheel_file:
        return False

    with te_wheel_file.open("r") as f:
        for line in f:
            if line.startswith("Root-Is-Purelib:"):
                return line.strip().split(":")[1].strip().lower() == "true"
    return False


@functools.lru_cache(maxsize=None)
def _find_shared_object_in_te_dir(te_path: Path, prefix: str) -> Optional[Path]:
    """
    Find a shared object file with the given prefix within the top level TE directory.

    The following locations are searched:
        1. Top level directory (editable install).
        2. `transformer_engine` directory (source install).
        3. `wheel_lib` directory (PyPI install).

    Returns None if no shared object files are found.
    Raises an error if multiple shared object files are found.
    """

    # Ensure top level dir exists and has the module before searching.
    if not te_path.is_dir() or not (te_path / "transformer_engine").exists():
        return None

    files = []
    search_paths = (
        te_path,  # Editable build.
        te_path / "transformer_engine",  # Regular source build.
        te_path / "transformer_engine/wheel_lib",  # PyPI.
    )

    # Search.
    for dir_path in search_paths:
        if not dir_path.is_dir():
            continue
        for file_path in dir_path.iterdir():
            if file_path.name.startswith(prefix) and file_path.suffix == _get_sys_extension():
                files.append(file_path)

    if len(files) == 0:
        return None
    if len(files) == 1:
        return files[0]
    raise RuntimeError(f"Multiple files found: {files}")


@functools.lru_cache(maxsize=None)
def _get_shared_object_file(library: str) -> Path:
    """
    Path to shared object file for a Transformer Engine library.

    TE libraries are 'core', 'torch', or 'jax'. This function first
    searches in the imported TE directory, and then in the
    site-packages directory.

    """

    # Check provided input and determine the correct prefix for .so.
    assert library in ("core", "torch", "jax"), f"Unsupported TE library {library}."
    if library == "core":
        so_prefix = "libtransformer_engine"
    else:
        so_prefix = f"transformer_engine_{library}"

    # Search for shared lib in imported directory
    te_path = Path(importlib.util.find_spec("transformer_engine").origin).parent.parent
    so_path = _find_shared_object_in_te_dir(te_path, so_prefix)
    if so_path is not None:
        return so_path

    # Search for shared lib in site-packages directory
    te_path = Path(sysconfig.get_paths()["purelib"])
    so_path = _find_shared_object_in_te_dir(te_path, so_prefix)
    if so_path is not None:
        return so_path

    raise FileNotFoundError(
        f"Could not find shared object file for Transformer Engine {library} lib."
    )


def get_te_core_package_info() -> Tuple[bool, str, str]:
    """
    Check if Tranformer Engine core package is installed.
    Returns the module name and version if found.
    """

    te_core_packages = ("transformer-engine-cu12", "transformer-engine-cu13")
    for package in te_core_packages:
        if _is_package_installed(package):
            return True, package, version(package)
    return False, "", ""


@functools.lru_cache(maxsize=None)
def load_framework_extension(framework: str) -> None:
    """
    Load shared library with Transformer Engine framework bindings
    and check verify correctness if installed via PyPI.
    """

    # Supported frameworks.
    assert framework in ("jax", "torch"), f"Unsupported framework {framework}"

    # Name of the framework extension library.
    module_name = f"transformer_engine_{framework}"

    # Name of the pip extra dependency for framework extensions from PyPI.
    extra_dep_name = module_name
    if framework == "torch":
        extra_dep_name = "pytorch"

    # Find the TE packages. The core and framework packages can only be installed via PyPI.
    # For the `transformer-engine` package, we need to check explicity.
    te_core_installed, te_core_package_name, te_core_version = get_te_core_package_info()
    te_framework_installed = _is_package_installed(module_name)
    te_installed = _is_package_installed("transformer_engine")
    te_installed_via_pypi = _is_package_installed_from_wheel("transformer_engine")

    assert te_installed, "Could not find `transformer_engine`."

    # If the framework extension pip package is installed, it means that TE is installed via
    # PyPI. For this case we need to make sure that the metapackage, the core lib, and framework
    # extension are all installed via PyPI and have matching versions.
    if te_framework_installed:
        assert te_installed_via_pypi, "Could not find `transformer-engine` PyPI package."
        assert te_core_installed, "Could not find TE core package `transformer-engine-cu*`."

        assert version(module_name) == version("transformer-engine") == te_core_version, (
            "Transformer Engine package version mismatch. Found"
            f" {module_name} v{version(module_name)}, transformer-engine"
            f" v{version('transformer-engine')}, and {te_core_package_name}"
            f" v{te_core_version}. Install transformer-engine using "
            f"'pip3 install --no-build-isolation transformer-engine[{extra_dep_name}]==VERSION'"
        )

    # After all checks are completed, load the shared object file.
    spec = importlib.util.spec_from_file_location(module_name, _get_shared_object_file(framework))
    solib = importlib.util.module_from_spec(spec)
    sys.modules[module_name] = solib
    spec.loader.exec_module(solib)


def sanity_checks_for_pypi_installation() -> None:
    """Ensure that package is installed correctly if using PyPI."""

    te_core_installed, te_core_package_name, te_core_version = get_te_core_package_info()
    te_installed = _is_package_installed("transformer_engine")
    te_installed_via_pypi = _is_package_installed_from_wheel("transformer_engine")

    assert te_installed, "Could not find `transformer-engine`."

    # If the core package is installed via PyPI.
    if te_core_installed:
        assert te_installed_via_pypi, "Could not find `transformer-engine` PyPI package."
        assert version("transformer-engine") == te_core_version, (
            "Transformer Engine package version mismatch. Found "
            f"transformer-engine v{version('transformer-engine')} "
            f"and {te_core_package_name} v{te_core_version}."
        )

    # Only the metapackage is found, invalid usecase.
    elif te_installed_via_pypi:
        raise RuntimeError(
            "Found empty `transformer-engine` meta package installed. "
            "Install `transformer-engine` with framework extensions via"
            "'pip3 install --no-build-isolation transformer-engine[pytorch,jax]==VERSION'"
            " or 'pip3 install transformer-engine[core]` for the TE core lib only. The `core_cu12`"
            " or `core_cu13` extra deps can be used to specify CUDA version for the TE core lib."
        )


@functools.lru_cache(maxsize=None)
def _get_sys_extension() -> str:
    """File extension for shared objects."""
    system = platform.system()

    if system == "Linux":
        return ".so"
    if system == "Darwin":
        return ".dylib"
    if system == "Windows":
        return ".dll"
    raise RuntimeError(f"Unsupported operating system ({system})")


@functools.lru_cache(maxsize=None)
def _nvidia_cudart_include_dir() -> str:
    """Returns the include directory for cuda_runtime.h if exists in python environment."""

    try:
        import nvidia
    except ModuleNotFoundError:
        return ""

    # Installing some nvidia-* packages, like nvshmem, create nvidia name, so "import nvidia"
    # above doesn't through. However, they don't set "__file__" attribute.
    if nvidia.__file__ is None:
        return ""

    include_dir = Path(nvidia.__file__).parent / "cuda_runtime"
    return str(include_dir) if include_dir.exists() else ""


@functools.lru_cache(maxsize=None)
def _load_cuda_library_from_python(lib_name: str, strict: bool = False):
    """
    Attempts to load shared object file installed via python packages.

    `lib_name` : Name of package as found in the `nvidia` dir in python environment.
    `strict` : If set to `True`, throw an error if lib is not found.
    """

    ext = _get_sys_extension()
    nvidia_dir = os.path.join(sysconfig.get_path("purelib"), "nvidia")

    # PyPI packages provided by nvidia libs exist
    # in 4 possible locations inside `nvidia`.
    # Check by order of priority.
    path_found = False
    if os.path.isdir(os.path.join(nvidia_dir, "cu13", lib_name)):
        so_paths = glob.glob(os.path.join(nvidia_dir, "cu13", lib_name, f"lib/lib*{ext}.*[0-9]"))
        path_found = len(so_paths) > 0

    if not path_found and os.path.isdir(os.path.join(nvidia_dir, "cu13")):
        so_paths = glob.glob(os.path.join(nvidia_dir, "cu13", f"lib/lib{lib_name}*{ext}.*[0-9]"))
        path_found = len(so_paths) > 0

    if not path_found and os.path.isdir(os.path.join(nvidia_dir, lib_name)):
        so_paths = glob.glob(os.path.join(nvidia_dir, lib_name, f"lib/lib*{ext}.*[0-9]"))
        path_found = len(so_paths) > 0

    if not path_found:
        so_paths = glob.glob(os.path.join(nvidia_dir, f"cuda_{lib_name}", f"lib/lib*{ext}.*[0-9]"))
        path_found = len(so_paths) > 0

    ctypes_handles = []

    if path_found:
        for so_path in so_paths:
            ctypes_handles.append(ctypes.CDLL(so_path, mode=ctypes.RTLD_GLOBAL))

    if strict and not path_found:
        raise RuntimeError(f"{lib_name} shared object not found.")

    return path_found, ctypes_handles


@functools.lru_cache(maxsize=None)
def _load_cuda_library_from_system(lib_name: str):
    """
    Attempts to load shared object file installed via system/cuda-toolkit.

    `lib_name`: Name of library to load without extension or `lib` prefix.
    """

    # Where to look for the shared lib in decreasing order of preference.
    paths = (
        os.environ.get(f"{lib_name.upper()}_HOME"),
        os.environ.get(f"{lib_name.upper()}_PATH"),
        os.environ.get("CUDA_HOME"),
        os.environ.get("CUDA_PATH"),
        "/usr/local/cuda",
    )

    for path in paths:
        if path is None:
            continue
        libs = glob.glob(f"{path}/**/lib{lib_name}{_get_sys_extension()}*", recursive=True)
        libs = [lib for lib in libs if "stub" not in lib]
        libs.sort(reverse=True, key=os.path.basename)
        if libs:
            return True, ctypes.CDLL(libs[0], mode=ctypes.RTLD_GLOBAL)

    # Search in LD_LIBRARY_PATH.
    try:
        _lib_handle = ctypes.CDLL(f"lib{lib_name}{_get_sys_extension()}", mode=ctypes.RTLD_GLOBAL)
        return True, _lib_handle
    except OSError:
        return False, None


@functools.lru_cache(maxsize=None)
def _load_cuda_library(lib_name: str):
    """
    Load given shared library.
    Prioritize loading from system/toolkit
    before checking python packages.
    """

    # Attempt to locate library in system.
    found, handle = _load_cuda_library_from_system(lib_name)
    if found:
        return True, handle

    # Attempt to locate library in Python dist-packages.
    found, handle = _load_cuda_library_from_python(lib_name)
    if found:
        return False, handle

    raise RuntimeError(f"{lib_name} shared object not found.")


@functools.lru_cache(maxsize=None)
def _load_core_library():
    """Load shared library with Transformer Engine C extensions"""
    return ctypes.CDLL(_get_shared_object_file("core"), mode=ctypes.RTLD_GLOBAL)


if "NVTE_PROJECT_BUILDING" not in os.environ or bool(int(os.getenv("NVTE_RELEASE_BUILD", "0"))):
    sanity_checks_for_pypi_installation()

    # `_load_cuda_library` is used for packages that must be loaded
    # during runtime. Both system and pypi packages are searched
    # and an error is thrown if not found.
    _, _CUDNN_LIB_CTYPES = _load_cuda_library("cudnn")
    system_nvrtc, _NVRTC_LIB_CTYPES = _load_cuda_library("nvrtc")
    system_curand, _CURAND_LIB_CTYPES = _load_cuda_library("curand")

    # This additional step is necessary to be able to install TE wheels
    # and import TE (without any guards) in an environment where the cuda
    # toolkit might be absent without being guarded
    load_libs_for_no_ctk = not system_nvrtc and not system_curand
    if load_libs_for_no_ctk:
        _CUBLAS_LIB_CTYPES = _load_cuda_library_from_python("cublas", strict=True)
        _CUDART_LIB_CTYPES = _load_cuda_library_from_python("cudart", strict=True)
        _CUDNN_ALL_LIB_CTYPES = _load_cuda_library_from_python("cudnn", strict=True)

    _TE_LIB_CTYPES = _load_core_library()

    # Needed to find the correct headers for NVRTC kernels.
    if not os.getenv("NVTE_CUDA_INCLUDE_DIR") and _nvidia_cudart_include_dir():
        os.environ["NVTE_CUDA_INCLUDE_DIR"] = _nvidia_cudart_include_dir()
