from contextlib import contextmanager

from util import remote_fn


def scrub(volume_id):
    import time
    from subprocess import CalledProcessError

    import rawfile_util
    from consts import VOLUME_IN_USE_EXIT_CODE

    img_dir = rawfile_util.img_dir(volume_id)
    if not img_dir.exists():
        return

    img_file = rawfile_util.img_file(volume_id)
    loops = rawfile_util.attached_loops(img_file)
    if len(loops) > 0:
        raise CalledProcessError(returncode=VOLUME_IN_USE_EXIT_CODE, cmd="")

    now = time.time()
    deleted_at = now
    gc_at = now  # TODO: GC sensitive PVCs later
    rawfile_util.patch_metadata(volume_id, {"deleted_at": deleted_at, "gc_at": gc_at})
    rawfile_util.gc_if_needed(volume_id, dry_run=False)


def init_rawfile(volume_id, size):
    import time
    from subprocess import CalledProcessError
    from pathlib import Path

    import rawfile_util
    from volume_schema import LATEST_SCHEMA_VERSION
    from util import run
    from consts import RESOURCE_EXHAUSTED_EXIT_CODE

    img_dir = rawfile_util.img_dir(volume_id)
    img_dir.mkdir(exist_ok=True)
    img_file = Path(f"{img_dir}/disk.img")
    if img_file.exists():
        return
    rawfile_util.patch_metadata(
        volume_id,
        {
            "schema_version": LATEST_SCHEMA_VERSION,
            "volume_id": volume_id,
            "created_at": time.time(),
            "img_file": img_file.as_posix(),
            "size": size,
        },
    )
    run(f"truncate -s {size} {img_file}")


def get_capacity():
    import rawfile_util

    cap = rawfile_util.get_capacity()
    return max(0, cap)


@remote_fn
def expand_rawfile(volume_id, size):
    import rawfile_util

    from util import run
    from consts import RESOURCE_EXHAUSTED_EXIT_CODE

    img_file = rawfile_util.img_file(volume_id)
    size_inc = size - rawfile_util.metadata(volume_id)["size"]
    if size_inc <= 0:
        return

    rawfile_util.patch_metadata(
        volume_id,
        {"size": size},
    )
    run(f"truncate -s {size} {img_file}")


@contextmanager
def mount_root_subvol(volume_id):
    import tempfile
    import pathlib

    import rawfile_util
    from util import run

    root_subvol = tempfile.mkdtemp(prefix="rawfile-")

    img_file = rawfile_util.img_file(volume_id)
    loop_dev = rawfile_util.attach_loop(img_file)

    run(f"mount -t btrfs -o subvolid=0 {loop_dev} {root_subvol}")
    try:
        yield root_subvol
    finally:
        run(f"umount {root_subvol}")
        pathlib.Path(root_subvol).rmdir()


def btrfs_delete_snapshot(volume_id, name):
    import btrfsutil

    with mount_root_subvol(volume_id) as root_subvol:
        snapshots_dir = f"{root_subvol}/.snapshots"
        snapshot_path = f"{snapshots_dir}/{name}"
        btrfsutil.delete_subvolume(snapshot_path)


def btrfs_create_snapshot(volume_id, name):
    import btrfsutil
    import time
    import pathlib

    # TODO: check fstype

    with mount_root_subvol(volume_id) as root_subvol:
        default_subvol_id = btrfsutil.get_default_subvolume(root_subvol)
        default_subvol = btrfsutil.subvolume_path(root_subvol, default_subvol_id)
        default_subvol = f"{root_subvol}/{default_subvol}"

        snapshots_dir = f"{root_subvol}/.snapshots"
        pathlib.Path(snapshots_dir).mkdir(parents=True, exist_ok=True)

        snapshot_subvol = f"{snapshots_dir}/{name}"
        btrfsutil.create_snapshot(default_subvol, snapshot_subvol, read_only=True)

    snapshot_id = f"{volume_id}/{name}"
    creation_time_ns = time.time_ns()
    return snapshot_id, creation_time_ns