#!/usr/bin/env python3

import errno
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_branches
from posix_parity import mergerfs_get_option
from posix_parity import mergerfs_set_option
from posix_parity import temp_dir
from posix_parity import touch


SKIP = 77


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

    mount = sys.argv[1]

    try:
        orig_moveonenospc = mergerfs_get_option(mount, "moveonenospc")
    except (PermissionError, FileNotFoundError):
        print("moveonenospc runtime option unavailable", end="")
        return SKIP
    except OSError as exc:
        if exc.errno == errno.EOPNOTSUPP:
            print("moveonenospc runtime option unsupported", end="")
            return SKIP
        raise

    branches = mergerfs_branches(mount)
    if len(branches) < 2:
        print("moveonenospc test requires at least 2 branches", end="")
        return SKIP

    # The documented feature only runs after write returns ENOSPC/EDQUOT. This
    # generic mountpoint test cannot safely force a branch into that state.
    merge_base = temp_dir(mount)

    try:
        mergerfs_set_option(mount, "moveonenospc", "mfs")
        if mergerfs_get_option(mount, "moveonenospc") != "mfs":
            return fail("moveonenospc: failed to set documented policy value")

        merge_file = join(merge_base, "enospc_test")
        touch(merge_file, b"test data for enospc")

        if not os.path.exists(merge_file):
            return fail("moveonenospc: file was not created")

        fullpath = None
        try:
            fullpath = os.getxattr(merge_file, "user.mergerfs.fullpath").decode()
        except OSError:
            pass

        if fullpath and not os.path.exists(fullpath):
            return fail(f"moveonenospc: fullpath does not exist on disk: {fullpath}")

        with open(merge_file, "r") as f:
            content = f.read()

        if content != "test data for enospc":
            return fail(f"moveonenospc: file content mismatch: got {content!r}")

        mergerfs_set_option(mount, "moveonenospc", orig_moveonenospc)

        print("moveonenospc ENOSPC path requires a constrained branch", end="")
        return SKIP
    except Exception as exc:
        try:
            mergerfs_set_option(mount, "moveonenospc", orig_moveonenospc)
        except Exception:
            pass
        return fail(str(exc))
    finally:
        cleanup_dir(merge_base)


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