#!/usr/bin/env python3

import array
import fcntl
import os
import termios
import sys
import tempfile

from posix_parity import compare_calls
from posix_parity import fail
from posix_parity import join
from posix_parity import touch


def fionread(fd):
    buf = array.array("i", [0])
    fcntl.ioctl(fd, termios.FIONREAD, buf, True)
    return buf[0]


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

    mount = sys.argv[1]

    with tempfile.TemporaryDirectory() as native:
        merge_file = join(mount, "posix-ioctl/file")
        native_file = join(native, "posix-ioctl/file")
        touch(merge_file, b"hello-world")
        touch(native_file, b"hello-world")

        mfd = os.open(merge_file, os.O_RDONLY)
        nfd = os.open(native_file, os.O_RDONLY)
        try:
            err = compare_calls("ioctl FIONREAD", lambda: fionread(mfd), lambda: fionread(nfd), lambda a, b: a == b)
            if err:
                return fail(err)

            os.lseek(mfd, 5, os.SEEK_SET)
            os.lseek(nfd, 5, os.SEEK_SET)
            err = compare_calls(
                "ioctl FIONREAD after seek",
                lambda: fionread(mfd),
                lambda: fionread(nfd),
                lambda a, b: a == b,
            )
            if err:
                return fail(err)
        finally:
            os.close(mfd)
            os.close(nfd)

    return 0


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