#!/usr/bin/env python3

import ctypes
import os
import sys
import tempfile

from posix_parity import cleanup_dir
from posix_parity import compare_calls
from posix_parity import fail
from posix_parity import join
from posix_parity import mergerfs_mount
from posix_parity import temp_dir
from posix_parity import touch


libc = ctypes.CDLL(None, use_errno=True)
libc.syncfs.argtypes = [ctypes.c_int]
libc.syncfs.restype = ctypes.c_int


def syncfs_fd(fd):
    ctypes.set_errno(0)
    rv = libc.syncfs(fd)
    if rv == 0:
        return 0
    err = ctypes.get_errno()
    raise OSError(err, os.strerror(err))


def main():
    try:
        with mergerfs_mount() as (mount, _):
            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_file = join(merge_base, "file")
                    native_file = join(native_base, "file")
                    touch(merge_file, b"x")
                    touch(native_file, b"x")

                    mfd = os.open(merge_file, os.O_RDONLY)
                    nfd = os.open(native_file, os.O_RDONLY)
                    try:
                        err = compare_calls("syncfs success", lambda: syncfs_fd(mfd), lambda: syncfs_fd(nfd))
                        if err:
                            return fail(err)
                    finally:
                        os.close(mfd)
                        os.close(nfd)

                    err = compare_calls("syncfs EBADF", lambda: syncfs_fd(-1), lambda: syncfs_fd(-1))
                    if err:
                        return fail(err)

                    return 0
                finally:
                    cleanup_dir(merge_base)
    except RuntimeError as exc:
        print(str(exc), end="")
        return 77


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