#!/usr/bin/env python3
"""Guard VC6 C89 declaration order in PyFile_OpenCodeObject."""
import sys
from pathlib import Path
from typing import NoReturn


def fail(message: str) -> NoReturn:
    print(message, file=sys.stderr)
    raise SystemExit(1)


def function_body(source, signature):
    start = source.find(signature)
    if start < 0:
        fail(f"missing function signature: {signature}")
    brace = source.find("{", start + len(signature))
    if brace < 0:
        fail("missing function body")
    depth = 0
    for end in range(brace, len(source)):
        if source[end] == "{":
            depth += 1
        elif source[end] == "}":
            depth -= 1
            if depth == 0:
                return source[brace + 1:end]
    fail("unterminated function body")


path = Path(sys.argv[1])
source = path.read_text(encoding="utf-8")
body = function_body(source, "PyFile_OpenCodeObject(PyObject *path)")
expected_decl = "    Py_OpenCodeHookFunction hook;"
if expected_decl not in body:
    fail("hook must be declared without initializer at function entry")
if "Py_OpenCodeHookFunction hook =" in body:
    fail("hook declaration must not be initialized at declaration")
validation = body.find("if (!PyUnicode_Check(path))")
assignment = body.find("hook = _PyRuntime.open_code_hook;")
if validation < 0 or assignment < 0 or assignment < validation:
    fail("hook lookup must remain after path validation")
if body.find("return NULL;", validation) > assignment:
    fail("hook lookup must remain after invalid-path early return")
print("fileobject open-code hook C89 declaration and validation order: PASS")