Radicale/radicale/storage/__init__.py

# This file is part of Radicale Server - Calendar 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/>.

"""
Storage backends.

This module loads the storage backend, according to the storage configuration.

Default storage uses one folder per collection and one file per collection
entry.

"""

import json
from contextlib import contextmanager
from hashlib import md5
from importlib import import_module

import pkg_resources
import vobject

from radicale.log import logger

INTERNAL_TYPES = ("multifilesystem",)

CACHE_DEPS = ("radicale", "vobject", "python-dateutil",)
CACHE_VERSION = (";".join(pkg_resources.get_distribution(pkg).version
                          for pkg in CACHE_DEPS) + ";").encode()


def load(configuration):
    """Load the storage manager chosen in configuration."""
    storage_type = configuration.get("storage", "type")
    if storage_type in INTERNAL_TYPES:
        module = "radicale.storage.%s" % storage_type
    else:
        module = storage_type
    try:
        class_ = import_module(module).Collection
    except Exception as e:
        raise RuntimeError("Failed to load storage module %r: %s" %
                           (storage_type, e)) from e
    logger.info("Storage type is %r", storage_type)

    class CollectionCopy(class_):
        """Collection copy, avoids overriding the original class attributes."""
    CollectionCopy.configuration = configuration
    CollectionCopy.static_init()
    return CollectionCopy


class ComponentExistsError(ValueError):
    def __init__(self, path):
        message = "Component already exists: %r" % path
        super().__init__(message)


class ComponentNotFoundError(ValueError):
    def __init__(self, path):
        message = "Component doesn't exist: %r" % path
        super().__init__(message)


class BaseCollection:

    # Overriden on copy by the "load" function
    configuration = None

    # Properties of instance
    """The sanitized path of the collection without leading or trailing ``/``.
    """
    path = ""

    @classmethod
    def static_init():
        """init collection copy"""
        pass

    @property
    def owner(self):
        """The owner of the collection."""
        return self.path.split("/", maxsplit=1)[0]

    @property
    def is_principal(self):
        """Collection is a principal."""
        return bool(self.path) and "/" not in self.path

    @classmethod
    def discover(cls, path, depth="0"):
        """Discover a list of collections under the given ``path``.

        ``path`` is sanitized.

        If ``depth`` is "0", only the actual object under ``path`` is
        returned.

        If ``depth`` is anything but "0", it is considered as "1" and direct
        children are included in the result.

        The root collection "/" must always exist.

        """
        raise NotImplementedError

    @classmethod
    def move(cls, item, to_collection, to_href):
        """Move an object.

        ``item`` is the item to move.

        ``to_collection`` is the target collection.

        ``to_href`` is the target name in ``to_collection``. An item with the
        same name might already exist.

        """
        if item.collection.path == to_collection.path and item.href == to_href:
            return
        to_collection.upload(to_href, item)
        item.collection.delete(item.href)

    @property
    def etag(self):
        """Encoded as quoted-string (see RFC 2616)."""
        etag = md5()
        for item in self.get_all():
            etag.update((item.href + "/" + item.etag).encode("utf-8"))
        etag.update(json.dumps(self.get_meta(), sort_keys=True).encode())
        return '"%s"' % etag.hexdigest()

    @classmethod
    def create_collection(cls, href, items=None, props=None):
        """Create a collection.

        ``href`` is the sanitized path.

        If the collection already exists and neither ``collection`` nor
        ``props`` are set, this method shouldn't do anything. Otherwise the
        existing collection must be replaced.

        ``collection`` is a list of vobject components.

        ``props`` are metadata values for the collection.

        ``props["tag"]`` is the type of collection (VCALENDAR or
        VADDRESSBOOK). If the key ``tag`` is missing, it is guessed from the
        collection.

        """
        raise NotImplementedError

    def sync(self, old_token=None):
        """Get the current sync token and changed items for synchronization.

        ``old_token`` an old sync token which is used as the base of the
        delta update. If sync token is missing, all items are returned.
        ValueError is raised for invalid or old tokens.

        WARNING: This simple default implementation treats all sync-token as
                 invalid. It adheres to the specification but some clients
                 (e.g. InfCloud) don't like it. Subclasses should provide a
                 more sophisticated implementation.

        """
        token = "http://radicale.org/ns/sync/%s" % self.etag.strip("\"")
        if old_token:
            raise ValueError("Sync token are not supported")
        return token, self.list()

    def list(self):
        """List collection items."""
        raise NotImplementedError

    def get(self, href):
        """Fetch a single item."""
        raise NotImplementedError

    def get_multi(self, hrefs):
        """Fetch multiple items.

        Functionally similar to ``get``, but might bring performance benefits
        on some storages when used cleverly. It's not required to return the
        requested items in the correct order. Duplicated hrefs can be ignored.

        Returns tuples with the href and the item or None if the item doesn't
        exist.

        """
        return ((href, self.get(href)) for href in hrefs)

    def get_all(self):
        """Fetch all items.

        Functionally similar to ``get``, but might bring performance benefits
        on some storages when used cleverly.

        """
        return map(self.get, self.list())

    def get_all_filtered(self, filters):
        """Fetch all items with optional filtering.

        This can largely improve performance of reports depending on
        the filters and this implementation.

        Returns tuples in the form ``(item, filters_matched)``.
        ``filters_matched`` is a bool that indicates if ``filters`` are fully
        matched.

        This returns all events by default
        """
        return ((item, False) for item in self.get_all())

    def has(self, href):
        """Check if an item exists by its href.

        Functionally similar to ``get``, but might bring performance benefits
        on some storages when used cleverly.

        """
        return self.get(href) is not None

    def has_uid(self, uid):
        """Check if a UID exists in the collection."""
        for item in self.get_all():
            if item.uid == uid:
                return True
        return False

    def upload(self, href, item):
        """Upload a new or replace an existing item."""
        raise NotImplementedError

    def delete(self, href=None):
        """Delete an item.

        When ``href`` is ``None``, delete the collection.

        """
        raise NotImplementedError

    def get_meta(self, key=None):
        """Get metadata value for collection.

        Return the value of the property ``key``. If ``key`` is ``None`` return
        a dict with all properties

        """
        raise NotImplementedError

    def set_meta(self, props):
        """Set metadata values for collection.

        ``props`` a dict with values for properties.

        """
        raise NotImplementedError

    @property
    def last_modified(self):
        """Get the HTTP-datetime of when the collection was modified."""
        raise NotImplementedError

    def serialize(self):
        """Get the unicode string representing the whole collection."""
        if self.get_meta("tag") == "VCALENDAR":
            in_vcalendar = False
            vtimezones = ""
            included_tzids = set()
            vtimezone = []
            tzid = None
            components = ""
            # Concatenate all child elements of VCALENDAR from all items
            # together, while preventing duplicated VTIMEZONE entries.
            # VTIMEZONEs are only distinguished by their TZID, if different
            # timezones share the same TZID this produces errornous ouput.
            # VObject fails at this too.
            for item in self.get_all():
                depth = 0
                for line in item.serialize().split("\r\n"):
                    if line.startswith("BEGIN:"):
                        depth += 1
                    if depth == 1 and line == "BEGIN:VCALENDAR":
                        in_vcalendar = True
                    elif in_vcalendar:
                        if depth == 1 and line.startswith("END:"):
                            in_vcalendar = False
                        if depth == 2 and line == "BEGIN:VTIMEZONE":
                            vtimezone.append(line + "\r\n")
                        elif vtimezone:
                            vtimezone.append(line + "\r\n")
                            if depth == 2 and line.startswith("TZID:"):
                                tzid = line[len("TZID:"):]
                            elif depth == 2 and line.startswith("END:"):
                                if tzid is None or tzid not in included_tzids:
                                    vtimezones += "".join(vtimezone)
                                    included_tzids.add(tzid)
                                vtimezone.clear()
                                tzid = None
                        elif depth >= 2:
                            components += line + "\r\n"
                    if line.startswith("END:"):
                        depth -= 1
            template = vobject.iCalendar()
            displayname = self.get_meta("D:displayname")
            if displayname:
                template.add("X-WR-CALNAME")
                template.x_wr_calname.value_param = "TEXT"
                template.x_wr_calname.value = displayname
            description = self.get_meta("C:calendar-description")
            if description:
                template.add("X-WR-CALDESC")
                template.x_wr_caldesc.value_param = "TEXT"
                template.x_wr_caldesc.value = description
            template = template.serialize()
            template_insert_pos = template.find("\r\nEND:VCALENDAR\r\n") + 2
            assert template_insert_pos != -1
            return (template[:template_insert_pos] +
                    vtimezones + components +
                    template[template_insert_pos:])
        elif self.get_meta("tag") == "VADDRESSBOOK":
            return "".join((item.serialize() for item in self.get_all()))
        return ""

    @classmethod
    @contextmanager
    def acquire_lock(cls, mode, user=None):
        """Set a context manager to lock the whole storage.

        ``mode`` must either be "r" for shared access or "w" for exclusive
        access.

        ``user`` is the name of the logged in user or empty.

        """
        raise NotImplementedError

    @classmethod
    def verify(cls):
        """Check the storage for errors."""
        return True