from contextlib import suppress from itertools import groupby from typing import Iterable, Set from sqlalchemy import inspect from sqlalchemy.util import OrderedSet from ereuse_devicehub.db import db from ereuse_devicehub.resources.device.exceptions import NeedsId from ereuse_devicehub.resources.device.models import Component, Computer, Device from ereuse_devicehub.resources.event.models import Remove from ereuse_devicehub.resources.tag.model import Tag from teal.db import ResourceNotFound from teal.marshmallow import ValidationError class Sync: """Synchronizes the device and components with the database.""" def run(self, device: Device, components: Iterable[Component] or None) -> (Device, OrderedSet): """ Synchronizes the device and components with the database. Identifies if the device and components exist in the database and updates / inserts them as necessary. Passed-in parameters have to be transient, or said differently, not-db-synced objects, or otherwise they would end-up being added in the session. `Learn more... `_. This performs Add / Remove as necessary. :param device: The device to add / update to the database. :param components: Components that are inside of the device. This method performs Add and Remove events so the device ends up with these components. Components are added / updated accordingly. If this is empty, all components are removed. If this is None, it means that we are not providing info about the components, in which case we keep the already existing components of the device –we don't touch them. :return: A tuple of: 1. The device from the database (with an ID) whose ``components`` field contain the db algorithm_version of the passed-in components. 2. A list of Add / Remove (not yet added to session). """ db_device = self.execute_register(device) db_components, events = OrderedSet(), OrderedSet() if components is not None: # We have component info (see above) assert isinstance(db_device, Computer) blacklist = set() # type: Set[int] not_new_components = set() for component in components: db_component, is_new = self.execute_register_component(component, blacklist, parent=db_device) db_components.add(db_component) if not is_new: not_new_components.add(db_component) # We only want to perform Add/Remove to not new components events = self.add_remove(db_device, not_new_components) db_device.components = db_components return db_device, events def execute_register_component(self, component: Component, blacklist: Set[int], parent: Computer): """ Synchronizes one component to the DB. This method is a specialization of :meth:`.execute_register` but for components that are inside parents. This method assumes components don't have tags, and it tries to identify a non-hid component by finding a :meth:`ereuse_devicehub.resources.device.models.Component. similar_one`. :param component: The component to sync. :param blacklist: A set of components already found by Component.similar_one(). Pass-in an empty Set. :param parent: For components, the computer that contains them. Helper used by Component.similar_one(). :return: A tuple with: - The synced component. See :meth:`.execute_register` for more info. - A flag stating if the device is new or it already existed in the DB. """ assert inspect(component).transient, 'Component should not be synced from DB' try: if component.hid: db_component = Device.query.filter_by(hid=component.hid).one() else: # Is there a component similar to ours? db_component = component.similar_one(parent, blacklist) # We blacklist this component so we # ensure we don't get it again for another component # with the same physical properties blacklist.add(db_component.id) except ResourceNotFound: db.session.add(component) db.session.flush() db_component = component is_new = True else: self.merge(component, db_component) is_new = False return db_component, is_new def execute_register(self, device: Device) -> Device: """ Synchronizes one device to the DB. This method tries to get an existing device using the HID or one of the tags, and... - if it already exists it returns a "local synced algorithm_version" –the same ``device`` you passed-in but with updated values from the database. In this case we do not "touch" any of its values on the DB. - If it did not exist, a new device is created in the db. This method validates that all passed-in tags (``device.tags``), if linked, are linked to the same device, ditto for the hid. Finally it links the tags with the device. If you pass-in a component that is inside a parent, use :meth:`.execute_register_component` as it has more specialized methods to handle them. :param device: The device to synchronize to the DB. :raise NeedsId: The device has not any identifier we can use. To still create the device use ``force_creation``. :raise DatabaseError: Any other error from the DB. :return: The synced device from the db with the tags linked. """ assert inspect(device).transient, 'Device cannot be already synced from DB' assert all(inspect(tag).transient for tag in device.tags), 'Tags cannot be synced from DB' if not device.tags and not device.hid: # We cannot identify this device raise NeedsId() db_device = None if device.hid: with suppress(ResourceNotFound): db_device = Device.query.filter_by(hid=device.hid).one() tags = {Tag.query.filter_by(id=tag.id).one() for tag in device.tags} # type: Set[Tag] linked_tags = {tag for tag in tags if tag.device_id} # type: Set[Tag] if linked_tags: sample_tag = next(iter(linked_tags)) for tag in linked_tags: if tag.device_id != sample_tag.device_id: raise MismatchBetweenTags(tag, sample_tag) # Linked to different devices if db_device: # Device from hid if sample_tag.device_id != db_device.id: # Device from hid != device from tags raise MismatchBetweenTagsAndHid(db_device.id, db_device.hid) else: # There was no device from hid db_device = sample_tag.device if db_device: # Device from hid or tags self.merge(device, db_device) else: # Device is new and tags are not linked to a device device.tags.clear() # We don't want to add the transient dummy tags db.session.add(device) db_device = device db_device.tags |= tags # Union of tags the device had plus the (potentially) new ones db.session.flush() assert db_device is not None return db_device @staticmethod def merge(device: Device, db_device: Device): """ Copies the physical properties of the device to the db_device. This method mutates db_device. """ for field_name, value in device.physical_properties.items(): if value is not None: setattr(db_device, field_name, value) @staticmethod def add_remove(device: Computer, components: Set[Component]) -> OrderedSet: """ Generates the Add and Remove events (but doesn't add them to session). :param device: A device which ``components`` attribute contains the old list of components. The components that are not in ``components`` will be Removed. :param components: List of components that are potentially to be Added. Some of them can already exist on the device, in which case they won't be re-added. :return: A list of Add / Remove events. """ # Note that we create the Remove events before the Add ones events = OrderedSet() old_components = set(device.components) adding = components - old_components if adding: # For the components we are adding, let's remove them from their old parents def g_parent(component: Component) -> Device: return component.parent or Computer(id=0) # Computer with id 0 is our Identity for parent, _components in groupby(sorted(adding, key=g_parent), key=g_parent): if parent.id != 0: # Is not Computer Identity events.add(Remove(device=parent, components=OrderedSet(_components))) return events class MismatchBetweenTags(ValidationError): def __init__(self, tag: Tag, other_tag: Tag, field_names={'device.tags'}): message = '{!r} and {!r} are linked to different devices.'.format(tag, other_tag) super().__init__(message, field_names) class MismatchBetweenTagsAndHid(ValidationError): def __init__(self, device_id: int, hid: str, field_names={'device.hid'}): message = 'Tags are linked to device {} but hid refers to device {}.'.format(device_id, hid) super().__init__(message, field_names)