#!/usr/bin/env python3
"""Check structseq_repr's value/repr declarations and ownership/order."""
import re
import sys
from pathlib import Path

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/structseq.c")
match = re.search(
    r"static PyObject \*\nstructseq_repr\(PyStructSequence \*obj\)\n\{(.*?)\n\}",
    source.read_text(),
    re.S,
)
assert match, "structseq_repr definition not found"
body = match.group(1)
assert re.match(
    r"\s*PyTypeObject \*typ = Py_TYPE\(obj\);"
    r"\s*_PyUnicodeWriter writer;\s*Py_ssize_t i;"
    r"\s*PyObject \*value;\s*PyObject \*repr;",
    body,
), "structseq_repr: VC6 requires value and repr in the function entry declaration block"
for variable in ("value", "repr"):
    assert len(re.findall(r"\bPyObject\s*\*" + variable + r"\b", body)) == 1, (
        "declare " + variable + " exactly once"
    )
    assert len(re.findall(r"\b" + variable + r"\s*=(?!=)", body)) == 1, (
        "assign " + variable + " exactly once at its original evaluation point"
    )
expected = """
        Py_DECREF(name);

        if (_PyUnicodeWriter_WriteChar(&writer, '=') < 0) {
            goto error;
        }

        value = PyStructSequence_GET_ITEM(obj, i);
        assert(value != NULL);
        repr = PyObject_Repr(value);
        if (repr == NULL) {
            goto error;
        }
        if (_PyUnicodeWriter_WriteStr(&writer, repr) < 0) {
            Py_DECREF(repr);
            goto error;
        }
        Py_DECREF(repr);
    }

    if (_PyUnicodeWriter_WriteChar(&writer, ')') < 0) {
        goto error;
    }

    return _PyUnicodeWriter_Finish(&writer);

error:
    _PyUnicodeWriter_Dealloc(&writer);
    return NULL;
"""
assert re.sub(r"\s+", "", body).endswith(re.sub(r"\s+", "", expected)), (
    "preserve name cleanup, '=' output, borrowed value lookup, repr creation, "
    "write/decref paths, and writer finish/error cleanup order"
)
assert len(re.findall(r"\bvalue\b", body)) == 4, "preserve borrowed value ownership"
assert len(re.findall(r"\brepr\b", re.sub(r"/\*.*?\*/", "", body, flags=re.S))) == 6, (
    "preserve repr ownership and both decref paths"
)
print("structseq_repr value/repr C89 declarations and ownership/order: PASS")