# Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
#
# NVIDIA CORPORATION and its licensors retain all intellectual property
# and proprietary rights in and to this software, related documentation
# and any modifications thereto.  Any use, reproduction, disclosure or
# distribution of this software and related documentation without an express
# license agreement from NVIDIA CORPORATION is strictly prohibited.

import glob
import os
import re
import uuid
import hashlib
import tempfile
import shutil
import tensorflow as tf
from tensorflow.python.client import device_lib # pylint: disable=no-name-in-module

#----------------------------------------------------------------------------
# Global options.

_nvdiffrast_cache_dir = None

def set_cache_dir(path: str) -> None:
    '''Set CUDA kernel compilation temp dir.

    If `set_cache_dir` is not called, the cache directory will default to
    one of the below:

    - Value of NVDIFFRAST_CACHE_DIR env var, if set
    - $HOME/.cache/nvdiffrast if HOME env var is set
    - $USERPROFILE/.cache/nvdiffrast if USERPROFILE is set.

    Args:
      path: Where to save CUDA kernel build temporaries
    '''
    global _nvdiffrast_cache_dir
    _nvdiffrast_cache_dir = path

def make_cache_dir_path(*paths: str) -> str:
    if _nvdiffrast_cache_dir is not None:
        return os.path.join(_nvdiffrast_cache_dir, *paths)
    if 'NVDIFFRAST_CACHE_DIR' in os.environ:
        return os.path.join(os.environ['NVDIFFRAST_CACHE_DIR'], *paths)
    if 'HOME' in os.environ:
        return os.path.join(os.environ['HOME'], '.cache', 'nvdiffrast', *paths)
    if 'USERPROFILE' in os.environ:
        return os.path.join(os.environ['USERPROFILE'], '.cache', 'nvdiffrast', *paths)
    return os.path.join(tempfile.gettempdir(), '.cache', 'nvdiffrast', *paths)

cuda_cache_version_tag = 'v1'
do_not_hash_included_headers = False # Speed up compilation by assuming that headers included by the CUDA code never change. Unsafe!
verbose = True # Print status messages to stdout.

#----------------------------------------------------------------------------
# Internal helper funcs.

def _find_compiler_bindir():
    hostx64_paths = sorted(glob.glob('C:/Program Files (x86)/Microsoft Visual Studio/*/Enterprise/VC/Tools/MSVC/*/bin/Hostx64/x64'), reverse=True)
    if hostx64_paths != []:
        return hostx64_paths[0]
    hostx64_paths = sorted(glob.glob('C:/Program Files (x86)/Microsoft Visual Studio/*/Professional/VC/Tools/MSVC/*/bin/Hostx64/x64'), reverse=True)
    if hostx64_paths != []:
        return hostx64_paths[0]
    hostx64_paths = sorted(glob.glob('C:/Program Files (x86)/Microsoft Visual Studio/*/BuildTools/VC/Tools/MSVC/*/bin/Hostx64/x64'), reverse=True)
    if hostx64_paths != []:
        return hostx64_paths[0]
    hostx64_paths = sorted(glob.glob('C:/Program Files (x86)/Microsoft Visual Studio/*/Community/VC/Tools/MSVC/*/bin/Hostx64/x64'), reverse=True)
    if hostx64_paths != []:
        return hostx64_paths[0]
    vc_bin_dir = 'C:/Program Files (x86)/Microsoft Visual Studio 14.0/vc/bin'
    if os.path.isdir(vc_bin_dir):
        return vc_bin_dir
    return None

def _get_compute_cap(device):
    caps_str = device.physical_device_desc
    m = re.search('compute capability: (\\d+).(\\d+)', caps_str)
    major = m.group(1)
    minor = m.group(2)
    return (major, minor)

def _get_cuda_gpu_arch_string():
    gpus = [x for x in device_lib.list_local_devices() if x.device_type == 'GPU']
    if len(gpus) == 0:
        raise RuntimeError('No GPU devices found')
    (major, minor) = _get_compute_cap(gpus[0])
    return 'sm_%s%s' % (major, minor)

def _run_cmd(cmd):
    with os.popen(cmd) as pipe:
        output = pipe.read()
        status = pipe.close()
    if status is not None:
        raise RuntimeError('NVCC returned an error. See below for full command line and output log:\n\n%s\n\n%s' % (cmd, output))

def _prepare_nvcc_cli(opts):
    cmd = 'nvcc ' + opts.strip()
    cmd += ' --disable-warnings'
    cmd += ' --include-path "%s"' % tf.sysconfig.get_include()
    cmd += ' --include-path "%s"' % os.path.join(tf.sysconfig.get_include(), 'external', 'protobuf_archive', 'src')
    cmd += ' --include-path "%s"' % os.path.join(tf.sysconfig.get_include(), 'external', 'com_google_absl')
    cmd += ' --include-path "%s"' % os.path.join(tf.sysconfig.get_include(), 'external', 'eigen_archive')

    compiler_bindir = _find_compiler_bindir()
    if compiler_bindir is None:
        # Require that _find_compiler_bindir succeeds on Windows.  Allow
        # nvcc to use whatever is the default on Linux.
        if os.name == 'nt':
            raise RuntimeError('Could not find MSVC/GCC/CLANG installation on this computer. Check compiler_bindir_search_path list in "%s".' % __file__)
    else:
        cmd += ' --compiler-bindir "%s"' % compiler_bindir
    cmd += ' 2>&1'
    return cmd

#----------------------------------------------------------------------------
# Main entry point.

_plugin_cache = dict()

def get_plugin(cuda_file, extra_nvcc_options=[]):
    cuda_file_base = os.path.basename(cuda_file)
    cuda_file_name, cuda_file_ext = os.path.splitext(cuda_file_base)

    # Already in cache?
    if cuda_file in _plugin_cache:
        return _plugin_cache[cuda_file]

    # Setup plugin.
    if verbose:
        print('Setting up TensorFlow plugin "%s": ' % cuda_file_base, end='', flush=True)
    try:
        # Hash CUDA source.
        md5 = hashlib.md5()
        with open(cuda_file, 'rb') as f:
            md5.update(f.read())
        md5.update(b'\n')

        # Hash headers included by the CUDA code by running it through the preprocessor.
        if not do_not_hash_included_headers:
            if verbose:
                print('Preprocessing... ', end='', flush=True)
            with tempfile.TemporaryDirectory() as tmp_dir:
                tmp_file = os.path.join(tmp_dir, cuda_file_name + '_tmp' + cuda_file_ext)
                _run_cmd(_prepare_nvcc_cli('"%s" --preprocess -o "%s" --keep --keep-dir "%s"' % (cuda_file, tmp_file, tmp_dir)))
                with open(tmp_file, 'rb') as f:
                    bad_file_str = ('"' + cuda_file.replace('\\', '/') + '"').encode('utf-8') # __FILE__ in error check macros
                    good_file_str = ('"' + cuda_file_base + '"').encode('utf-8')
                    for ln in f:
                        if not ln.startswith(b'# ') and not ln.startswith(b'#line '): # ignore line number pragmas
                            ln = ln.replace(bad_file_str, good_file_str)
                            md5.update(ln)
                    md5.update(b'\n')

        # Select compiler options.
        compile_opts = ''
        if os.name == 'nt':
            compile_opts += '"%s"' % os.path.join(tf.sysconfig.get_lib(), 'python', '_pywrap_tensorflow_internal.lib')
            compile_opts += ' --library-path="%s"' % (os.path.dirname(__file__) + r"\..\lib") # Find glew32s.lib during compilation.
        elif os.name == 'posix':
            compile_opts += '"%s"' % os.path.join(tf.sysconfig.get_lib(), 'python', '_pywrap_tensorflow_internal.so')
            compile_opts += ' --compiler-options \'-fPIC -D_GLIBCXX_USE_CXX11_ABI=0\''
        else:
            assert False # not Windows or Linux, w00t?
        compile_opts += ' --gpu-architecture=%s' % _get_cuda_gpu_arch_string()
        compile_opts += ' --use_fast_math'
        for opt in extra_nvcc_options:
            compile_opts += ' ' + opt
        nvcc_cmd = _prepare_nvcc_cli(compile_opts)

        # Hash build configuration.
        md5.update(('nvcc_cmd: ' + nvcc_cmd).encode('utf-8') + b'\n')
        md5.update(('tf.VERSION: ' + tf.VERSION).encode('utf-8') + b'\n')
        md5.update(('cuda_cache_version_tag: ' + cuda_cache_version_tag).encode('utf-8') + b'\n')

        # Compile if not already compiled.
        bin_file_ext = '.dll' if os.name == 'nt' else '.so'
        cuda_cache_path = make_cache_dir_path()
        bin_file = os.path.join(make_cache_dir_path(), cuda_file_name + '_' + md5.hexdigest() + bin_file_ext)
        if not os.path.isfile(bin_file):
            if verbose:
                print('Compiling... ', end='', flush=True)
            with tempfile.TemporaryDirectory() as tmp_dir:
                tmp_file = os.path.join(tmp_dir, cuda_file_name + '_tmp' + bin_file_ext)
                _run_cmd(nvcc_cmd + ' "%s" --shared -o "%s" --keep --keep-dir "%s"' % (cuda_file, tmp_file, tmp_dir))
                os.makedirs(cuda_cache_path, exist_ok=True)
                intermediate_file = os.path.join(cuda_cache_path, cuda_file_name + '_' + uuid.uuid4().hex + '_tmp' + bin_file_ext)
                shutil.copyfile(tmp_file, intermediate_file)
                os.rename(intermediate_file, bin_file) # atomic

        # Load.
        if verbose:
            print('Loading... ', end='', flush=True)
        plugin = tf.load_op_library(bin_file)

        # Add to cache.
        _plugin_cache[cuda_file] = plugin
        if verbose:
            print('Done.', flush=True)
        return plugin

    except:
        if verbose:
            print('Failed!', flush=True)
        raise

#----------------------------------------------------------------------------
