#!/usr/bin/env python3

import errno
import os
import sys
import tempfile

from posix_parity import cleanup_dir
from posix_parity import fail
from posix_parity import join
from posix_parity import temp_dir


def open_tmpfile(dirpath):
    return os.open(dirpath, os.O_TMPFILE | os.O_RDWR, 0o600)


def errno_of(call):
    try:
        fd = call()
        os.close(fd)
        return 0
    except OSError as exc:
        return exc.errno


def main():
    if len(sys.argv) != 2:
        print("usage: TEST_posix_tmpfile <mountpoint>", file=sys.stderr)
        return 1

    if not hasattr(os, "O_TMPFILE"):
        return 0

    mount = sys.argv[1]

    with tempfile.TemporaryDirectory() as native:
        merge_base = temp_dir(mount)
        try:
            native_base = join(native, os.path.basename(merge_base))
            os.makedirs(native_base, exist_ok=True)

            merge_dir = merge_base
            native_dir = native_base

            m_err = errno_of(lambda: open_tmpfile(merge_dir))
            n_err = errno_of(lambda: open_tmpfile(native_dir))
            # mergerfs does not currently support O_TMPFILE, so EOPNOTSUPP is
            # the expected result even when the native filesystem supports it.
            if m_err == errno.EOPNOTSUPP:
                return 0
            if m_err != n_err:
                return fail(f"O_TMPFILE support mismatch mergerfs_errno={m_err} native_errno={n_err}")

            # If unsupported on both, treat as skip-pass.
            if m_err in (errno.EOPNOTSUPP, errno.EISDIR, errno.EINVAL, errno.ENOSYS):
                return 0

            mfd = open_tmpfile(merge_dir)
            try:
                nfd = open_tmpfile(native_dir)
            except OSError:
                os.close(mfd)
                return fail("O_TMPFILE: native open failed after merge succeeded")
            try:
                mw = os.write(mfd, b"tmpfile-data")
                nw = os.write(nfd, b"tmpfile-data")
                if mw != nw:
                    return fail(f"O_TMPFILE write count mismatch mergerfs={mw} native={nw}")
            finally:
                os.close(mfd)
                os.close(nfd)

            return 0
        finally:
            cleanup_dir(merge_base)


if __name__ == "__main__":
    raise SystemExit(main())