# This file is part of Radicale - CalDAV and CardDAV server
# Copyright © 2014 Jean-Marc Martins
# Copyright © 2012-2017 Guillaume Ayoub
# Copyright © 2017-2018 Unrud <unrud@outlook.com>
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Radicale.  If not, see <http://www.gnu.org/licenses/>.

import os
import posixpath
from typing import Callable, ContextManager, Iterator, Optional, cast

from radicale import pathutils, types
from radicale.log import logger
from radicale.storage import multifilesystem
from radicale.storage.multifilesystem.base import StorageBase


@types.contextmanager
def _null_child_context_manager(path: str,
                                href: Optional[str]) -> Iterator[None]:
    yield


class StoragePartDiscover(StorageBase):

    def discover(
            self, path: str, depth: str = "0", child_context_manager: Optional[
                Callable[[str, Optional[str]], ContextManager[None]]] = None
            ) -> Iterator[types.CollectionOrItem]:
        # assert isinstance(self, multifilesystem.Storage)
        if child_context_manager is None:
            child_context_manager = _null_child_context_manager
        # Path should already be sanitized
        sane_path = pathutils.strip_path(path)
        attributes = sane_path.split("/") if sane_path else []

        folder = self._get_collection_root_folder()
        # Create the root collection
        self._makedirs_synced(folder)
        try:
            filesystem_path = pathutils.path_to_filesystem(folder, sane_path)
        except ValueError as e:
            # Path is unsafe
            logger.debug("Unsafe path %r requested from storage: %s",
                         sane_path, e, exc_info=True)
            return

        # Check if the path exists and if it leads to a collection or an item
        href: Optional[str]
        if not os.path.isdir(filesystem_path):
            if attributes and os.path.isfile(filesystem_path):
                href = attributes.pop()
            else:
                return
        else:
            href = None

        sane_path = "/".join(attributes)
        collection = self._collection_class(
            cast(multifilesystem.Storage, self),
            pathutils.unstrip_path(sane_path, True))

        if href:
            item = collection._get(href)
            if item is not None:
                yield item
            return

        yield collection

        if depth == "0":
            return

        for href in collection._list():
            with child_context_manager(sane_path, href):
                item = collection._get(href)
                if item is not None:
                    yield item

        for entry in os.scandir(filesystem_path):
            if not entry.is_dir():
                continue
            href = entry.name
            if not pathutils.is_safe_filesystem_path_component(href):
                if not href.startswith(".Radicale"):
                    logger.debug("Skipping collection %r in %r",
                                 href, sane_path)
                continue
            sane_child_path = posixpath.join(sane_path, href)
            child_path = pathutils.unstrip_path(sane_child_path, True)
            with child_context_manager(sane_child_path, None):
                yield self._collection_class(
                    cast(multifilesystem.Storage, self), child_path)
