#!/usr/bin/env python3
# libmisc/wrap-cc - Wrapper around GCC to enhance the preprocessor
#
# Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>
# SPDX-License-Identifier: AGPL-3.0-or-later

import os
import sys
import typing


def preprocess(all_args: list[str]) -> typing.NoReturn:
    _args = all_args

    def shift(n: int) -> list[str]:
        nonlocal _args
        ret = _args[:n]
        _args = _args[n:]
        return ret

    arg0 = shift(1)[0]
    flags: list[str] = []
    positional: list[str] = []
    while _args:
        if len(_args[0]) > 2 and _args[0][0] == "-" and _args[0][1] in "IDU":
            _args = [_args[0][:2], _args[0][2:], *_args[1:]]
        match _args[0]:
            # Mode
            case "-E" | "-quiet" | "-lang-asm":
                flags += shift(1)
            # Search path
            case "-I" | "-imultilib" | "-isystem":
                flags += shift(2)
            # Define/Undefine
            case "-D" | "-U":
                flags += shift(2)
            # Optimization
            case "-O0" | "-O1" | "-O2" | "-O3" | "-Os" | "-Ofast" | "-Og" | "-Oz":
                flags += shift(1)
            case "-g":
                flags += shift(1)
            # Output files
            case "-MD" | "-MF" | "-MT" | "-dumpbase" | "-dumpbase-ext":
                flags += shift(2)
            case "-o":
                flags += shift(2)
            # Other
            case _:
                if _args[0].startswith("-"):
                    if _args[0].startswith("-std="):
                        flags += shift(1)
                    elif _args[0].startswith("-m"):
                        flags += shift(1)
                    elif _args[0].startswith("-f"):
                        flags += shift(1)
                    elif _args[0].startswith("-W"):
                        flags += shift(1)
                    else:
                        raise ValueError(f"unknown flag: {_args!r}")
                else:
                    positional += shift(1)
    os.execvp(arg0, [arg0, *flags, *positional])


def main(all_args: list[str]) -> typing.NoReturn:
    if len(all_args) >= 2 and all_args[0].endswith("cc1") and all_args[1] == "-E":
        preprocess(all_args)
    else:
        os.execvp(all_args[0], all_args)


if __name__ == "__main__":
    main(sys.argv[1:])