#!/usr/bin/env python3

import os
import sys

from posix_parity import cleanup_dir
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


def main():
    try:
        with mergerfs_mount() as (mount, _):
            merge_base = temp_dir(mount)

            try:
                merge_file = join(merge_base, "testfile")
                touch(merge_file, b"hello world")

                fd = os.open(merge_file, os.O_RDWR)

                try:
                    data = os.read(fd, 4096)
                    if data != b"hello world":
                        return fail("read before unlink: expected 'hello world', got {!r}".format(data))

                    os.unlink(merge_file)

                    fd2 = os.dup(fd)
                    try:
                        os.lseek(fd2, 0, os.SEEK_SET)
                        data2 = os.read(fd2, 4096)
                        if data2 != b"hello world":
                            return fail("read after unlink via dup: expected 'hello world', got {!r}".format(data2))

                        os.lseek(fd, 0, os.SEEK_SET)
                        written = os.write(fd, b"modified")
                        if written != len(b"modified"):
                            return fail("write after unlink: wrote {}, expected {}".format(written, len(b"modified")))

                        os.lseek(fd, 0, os.SEEK_SET)
                        data3 = os.read(fd, 4096)
                        if not data3.startswith(b"modified"):
                            return fail("read back written data: got {!r} after writing 'modified'".format(data3))
                    finally:
                        os.close(fd2)
                finally:
                    os.close(fd)

                return 0
            except Exception as exc:
                return fail(str(exc))
            finally:
                try:
                    os.unlink(join(merge_base, "testfile"))
                except FileNotFoundError:
                    pass
                cleanup_dir(merge_base)
    except RuntimeError as exc:
        print(str(exc), end="")
        return 77


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