#!/usr/bin/env python3

import os
import sys
import tempfile

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


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

    mount = sys.argv[1]

    with tempfile.TemporaryDirectory() as native:
        merge_file = join(mount, "posix-release/file")
        native_file = join(native, "posix-release/file")

        touch(merge_file, b"abc")
        touch(native_file, b"abc")

        # Open + dup so one close does not release the underlying open-file state.
        mfd1 = os.open(merge_file, os.O_RDWR)
        nfd1 = os.open(native_file, os.O_RDWR)
        mfd2 = os.dup(mfd1)
        nfd2 = os.dup(nfd1)

        try:
            os.close(mfd1)
            os.close(nfd1)

            mw = os.write(mfd2, b"X")
            nw = os.write(nfd2, b"X")
            if mw != nw:
                return fail(f"release dup write mismatch mergerfs={mw} native={nw}")

            os.lseek(mfd2, 0, os.SEEK_SET)
            os.lseek(nfd2, 0, os.SEEK_SET)
            mr = os.read(mfd2, 4)
            nr = os.read(nfd2, 4)
            if mr != nr:
                return fail(f"release dup read mismatch mergerfs={mr!r} native={nr!r}")
        finally:
            os.close(mfd2)
            os.close(nfd2)

        with open(merge_file, "rb") as mf, open(native_file, "rb") as nf:
            md = mf.read()
            nd = nf.read()
        if md != nd:
            return fail(f"release final data mismatch mergerfs={md!r} native={nd!r}")

        # Closing same fd twice should map to EBADF on both.
        mfd = os.open(merge_file, os.O_RDONLY)
        nfd = os.open(native_file, os.O_RDONLY)
        os.close(mfd)
        os.close(nfd)
        try:
            os.close(mfd)
            m_err = 0
        except OSError as exc:
            m_err = exc.errno
        try:
            os.close(nfd)
            n_err = 0
        except OSError as exc:
            n_err = exc.errno
        if m_err != n_err:
            return fail(f"release EBADF mismatch mergerfs_errno={m_err} native_errno={n_err}")

        return 0


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