#!/usr/bin/env python

# Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# This is a tool to generate a stub (empty) implenentation of a C API header
# It matches match functions following the pattern:
#     DLL_PUBLIC rettype func_name(A a, B b, ...);
# also including linebreaks and extra spaces.
#
# Usage:
#     ./stubgen.py path/to/header.h > stub.c

import re
import sys

COPYRIGHT_NOTICE = """
// Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// THIS IS A STUB IMPLEMENTATION IMPLEMENTATION FILE ONLY MEANT FOR BUILD
// PURPOSES.

"""


def stubgen(header_filepath, out_file=sys.stdout):
    header_text = ""
    with open(header_filepath, "r") as file:
        header_text = file.read()

    print(COPYRIGHT_NOTICE, file=out_file)
    print("#include \"{}\"\n\n".format(header_filepath), file=out_file)

    FUNCTION_DECL_PATTERN = r"DLL_PUBLIC[\s]+(.*)[\s]+(.*)\(([^\)]*?)\);"
    for entry in re.finditer(FUNCTION_DECL_PATTERN, header_text):
        ret_type = entry.group(1)
        func_name = entry.group(2)
        args = entry.group(3)
        print('{} {}({}) {{\n}}\n\n'.format(ret_type, func_name, args), file=out_file)


if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser(
        description='Produces an empty stub implementation of a C header')
    parser.add_argument('header_filepath', metavar='header', type=str,
                        help='Path to the header file')
    parser.add_argument('--output', metavar='output', type=str, help='Path to the output file')
    args = parser.parse_args()

    f = open(args.output, 'w+') if args.output is not None else sys.stdout
    stubgen(args.header_filepath, out_file=f)
