# Copyright (c) 2016-present, Gregory Szorc

# All rights reserved.

#

# This software may be modified and distributed under the terms

# of the BSD license. See the LICENSE file for details.

from __future__ import absolute_import

import cffi

import distutils.ccompiler

import os

import re

import subprocess

import tempfile

HERE = os.path.abspath(os.path.dirname(__file__))

SOURCES = ['zstd/%s' % p for p in (

    'common/entropy_common.c',

    'common/error_private.c',

    'common/fse_decompress.c',

    'common/pool.c',

    'common/threading.c',

    'common/xxhash.c',

    'common/zstd_common.c',

    'compress/fse_compress.c',

    'compress/huf_compress.c',

    'compress/zstd_compress.c',

    'compress/zstd_double_fast.c',

    'compress/zstd_fast.c',

    'compress/zstd_lazy.c',

    'compress/zstd_ldm.c',

    'compress/zstd_opt.c',

    'compress/zstdmt_compress.c',

    'decompress/huf_decompress.c',

    'decompress/zstd_decompress.c',

    'dictBuilder/cover.c',

    'dictBuilder/divsufsort.c',

    'dictBuilder/zdict.c',

)]

# Headers whose preprocessed output will be fed into cdef().

HEADERS = [os.path.join(HERE, 'zstd', *p) for p in (

    ('zstd.h',),

    ('dictBuilder', 'zdict.h'),

)]

INCLUDE_DIRS = [os.path.join(HERE, d) for d in (

    'zstd',

    'zstd/common',

    'zstd/compress',

    'zstd/decompress',

    'zstd/dictBuilder',

)]

# cffi can't parse some of the primitives in zstd.h. So we invoke the

# preprocessor and feed its output into cffi.

compiler = distutils.ccompiler.new_compiler()

# Needed for MSVC.

if hasattr(compiler, 'initialize'):

    compiler.initialize()

# Distutils doesn't set compiler.preprocessor, so invoke the preprocessor

# manually.

if compiler.compiler_type == 'unix':

    args = list(compiler.executables['compiler'])

    args.extend([

        '-E',

        '-DZSTD_STATIC_LINKING_ONLY',

        '-DZDICT_STATIC_LINKING_ONLY',

    ])

elif compiler.compiler_type == 'msvc':

    args = [compiler.cc]

    args.extend([

        '/EP',

        '/DZSTD_STATIC_LINKING_ONLY',

        '/DZDICT_STATIC_LINKING_ONLY',

    ])

else:

    raise Exception('unsupported compiler type: %s' % compiler.compiler_type)

def preprocess(path):

    with open(path, 'rb') as fh:

        lines = []

        it = iter(fh)

        for l in it:

            # zstd.h includes <stddef.h>, which is also included by cffi's

            # boilerplate. This can lead to duplicate declarations. So we strip

            # this include from the preprocessor invocation.

            #

            # The same things happens for including zstd.h, so give it the same

            # treatment.

            #

            # We define ZSTD_STATIC_LINKING_ONLY, which is redundant with the inline

            # #define in zstdmt_compress.h and results in a compiler warning. So drop

            # the inline #define.

            if l.startswith((b'#include <stddef.h>',

                             b'#include "zstd.h"',

                             b'#define ZSTD_STATIC_LINKING_ONLY')):

                continue

            # ZSTDLIB_API may not be defined if we dropped zstd.h. It isn't

            # important so just filter it out.

            if l.startswith(b'ZSTDLIB_API'):

                l = l[len(b'ZSTDLIB_API '):]

            lines.append(l)

    fd, input_file = tempfile.mkstemp(suffix='.h')

    os.write(fd, b''.join(lines))

    os.close(fd)

    try:

        process = subprocess.Popen(args + [input_file], stdout=subprocess.PIPE)

        output = process.communicate()[0]

        ret = process.poll()

        if ret:

            raise Exception('preprocessor exited with error')

        return output

    finally:

        os.unlink(input_file)

def normalize_output(output):

    lines = []

    for line in output.splitlines():

        # CFFI's parser doesn't like __attribute__ on UNIX compilers.

        if line.startswith(b'__attribute__ ((visibility ("default"))) '):

            line = line[len(b'__attribute__ ((visibility ("default"))) '):]

        if line.startswith(b'__attribute__((deprecated('):

            continue

        elif b'__declspec(deprecated(' in line:

            continue

        lines.append(line)

    return b'\n'.join(lines)

ffi = cffi.FFI()

# zstd.h uses a possible undefined MIN(). Define it until

# https://github.com/facebook/zstd/issues/976 is fixed.

# *_DISABLE_DEPRECATE_WARNINGS prevents the compiler from emitting a warning

# when cffi uses the function. Since we statically link against zstd, even

# if we use the deprecated functions it shouldn't be a huge problem.

ffi.set_source('_zstd_cffi', '''

#define MIN(a,b) ((a)<(b) ? (a) : (b))

#define ZSTD_STATIC_LINKING_ONLY

#include <zstd.h>

#define ZDICT_STATIC_LINKING_ONLY

#define ZDICT_DISABLE_DEPRECATE_WARNINGS

#include <zdict.h>

''', sources=SOURCES,

     include_dirs=INCLUDE_DIRS,

     extra_compile_args=['-DZSTD_MULTITHREAD'])

DEFINE = re.compile(b'^\\#define ([a-zA-Z0-9_]+) ')

sources = []

# Feed normalized preprocessor output for headers into the cdef parser.

for header in HEADERS:

    preprocessed = preprocess(header)

    sources.append(normalize_output(preprocessed))

    # #define's are effectively erased as part of going through preprocessor.

    # So perform a manual pass to re-add those to the cdef source.

    with open(header, 'rb') as fh:

        for line in fh:

            line = line.strip()

            m = DEFINE.match(line)

            if not m:

                continue

            if m.group(1) == b'ZSTD_STATIC_LINKING_ONLY':

                continue

            # The parser doesn't like some constants with complex values.

            if m.group(1) in (b'ZSTD_LIB_VERSION', b'ZSTD_VERSION_STRING'):

                continue

            # The ... is magic syntax by the cdef parser to resolve the

            # value at compile time.

            sources.append(m.group(0) + b' ...')

cdeflines = b'\n'.join(sources).splitlines()

cdeflines = [l for l in cdeflines if l.strip()]

ffi.cdef(b'\n'.join(cdeflines).decode('latin1'))

if __name__ == '__main__':

    ffi.compile()