#!/usr/bin/env python3

import os
import sys

from posix_parity import fail
from posix_parity import mergerfs_get_option
from posix_parity import mergerfs_mount
from posix_parity import mergerfs_set_option


def main():
    try:
        with mergerfs_mount() as (mount, _):
            try:
                orig_statfs = mergerfs_get_option(mount, "statfs")
                orig_ignore = mergerfs_get_option(mount, "statfs-ignore")
            except (PermissionError, FileNotFoundError, OSError):
                return 0

            try:
                mergerfs_set_option(mount, "statfs", "base")

                mergerfs_set_option(mount, "statfs-ignore", "none")
                s_none = os.statvfs(mount)

                mergerfs_set_option(mount, "statfs-ignore", "nc")
                s_nc = os.statvfs(mount)

                mergerfs_set_option(mount, "statfs-ignore", "ro")
                s_ro = os.statvfs(mount)

                if s_nc.f_bavail > s_none.f_bavail:
                    return fail(
                        f"statfs-ignore=nc increased bavail unexpectedly nc={s_nc.f_bavail} none={s_none.f_bavail}"
                    )
                if s_ro.f_bavail > s_nc.f_bavail:
                    return fail(
                        f"statfs-ignore=ro increased bavail unexpectedly ro={s_ro.f_bavail} nc={s_nc.f_bavail}"
                    )

                mergerfs_set_option(mount, "statfs", "full")
                s_full = os.statvfs(mount)
                if s_full.f_bsize <= 0 or s_full.f_frsize <= 0:
                    return fail(
                        f"statfs=full invalid block sizes bsize={s_full.f_bsize} frsize={s_full.f_frsize}"
                    )
            except (PermissionError, FileNotFoundError, OSError):
                return 0
            finally:
                try:
                    mergerfs_set_option(mount, "statfs", orig_statfs)
                    mergerfs_set_option(mount, "statfs-ignore", orig_ignore)
                except OSError:
                    pass

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


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