#!/usr/bin/env python3
"""Replay native MSVC compile commands into /P source evidence on Windows."""

import argparse, ctypes, json, subprocess
from ctypes import wintypes
from pathlib import Path


def argv(command):
    fn = ctypes.windll.shell32.CommandLineToArgvW
    fn.argtypes = [wintypes.LPCWSTR, ctypes.POINTER(ctypes.c_int)]
    fn.restype = ctypes.POINTER(wintypes.LPWSTR)
    n = ctypes.c_int()
    p = fn(command, ctypes.byref(n))
    assert p
    try:
        return [p[i] for i in range(n.value)]
    finally:
        free = ctypes.windll.kernel32.LocalFree
        free.argtypes = [ctypes.c_void_p]
        free.restype = ctypes.c_void_p
        free(ctypes.cast(p, ctypes.c_void_p))


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("commands", type=Path)
    ap.add_argument("output", type=Path)
    a = ap.parse_args()
    a.output.mkdir(parents=True, exist_ok=True)
    records = []
    for i, c in enumerate(json.loads(a.commands.read_text())):
        if not Path(c["file"]).suffix.lower() in [".cpp", ".cc", ".cxx", ".c++"]:
            continue
        raw = c.get("arguments") or argv(c["command"])
        args = [raw[0]]
        for arg in raw[1:]:
            if arg.lower() in [
                "/c",
                "-c",
                "/fs",
                "/showincludes",
            ] or arg.lower().startswith(("/fo", "/fd", "/mp")):
                continue
            args.append(arg)
        output = (a.output / (str(i).zfill(5) + ".ii")).resolve()
        args += ["/P", "/Fi" + str(output)]
        subprocess.run(args, cwd=c["directory"], check=True)
        assert output.exists() and output.stat().st_size > 0
        records.append(
            {
                "source": c["file"],
                "directory": c["directory"],
                "original_command": c["command"],
                "preprocess_argv": args,
                "preprocessed": output.name,
            }
        )
    assert records, "No C++ preprocessing evidence"
    (a.output / "source-map.json").write_text(json.dumps(records, indent=2))


if __name__ == "__main__":
    main()