cti-python-stix2/stix2/environment.py

import copy

from .core import parse as _parse
from .datastore import CompositeDataSource, DataStoreMixin


class ObjectFactory(object):
    """Easily create STIX objects with default values for certain properties.

    Args:
        created_by_ref (optional): Default created_by_ref value to apply to all
            objects created by this factory.
        created (optional): Default created value to apply to all
            objects created by this factory.
        external_references (optional): Default `external_references` value to apply
            to all objects created by this factory.
        object_marking_refs (optional): Default `object_marking_refs` value to apply
            to all objects created by this factory.
        list_append (bool, optional): When a default is set for a list property like
            `external_references` or `object_marking_refs` and a value for
            that property is passed into `create()`, if this is set to True,
            that value will be added to the list alongside the default. If
            this is set to False, the passed in value will replace the
            default. Defaults to True.
    """

    def __init__(self, created_by_ref=None, created=None,
                 external_references=None, object_marking_refs=None,
                 list_append=True):

        self._defaults = {}
        if created_by_ref:
            self._defaults['created_by_ref'] = created_by_ref
        if created:
            self._defaults['created'] = created
            # If the user provides a default "created" time, we also want to use
            # that as the modified time.
            self._defaults['modified'] = created
        if external_references:
            self._defaults['external_references'] = external_references
        if object_marking_refs:
            self._defaults['object_marking_refs'] = object_marking_refs
        self._list_append = list_append
        self._list_properties = ['external_references', 'object_marking_refs']

    def create(self, cls, **kwargs):
        """Create a STIX object using object factory defaults.

        Args:
            cls: the python-stix2 class of the object to be created (eg. Indicator)
            **kwargs: The property/value pairs of the STIX object to be created
        """

        # Use self.defaults as the base, but update with any explicit args
        # provided by the user.
        properties = copy.deepcopy(self._defaults)
        if kwargs:
            if self._list_append:
                # Append provided items to list properties instead of replacing them
                for list_prop in set(self._list_properties).intersection(kwargs.keys(), properties.keys()):
                    kwarg_prop = kwargs.pop(list_prop)
                    if kwarg_prop is None:
                        del properties[list_prop]
                        continue
                    if not isinstance(properties[list_prop], list):
                        properties[list_prop] = [properties[list_prop]]

                    if isinstance(kwarg_prop, list):
                        properties[list_prop].extend(kwarg_prop)
                    else:
                        properties[list_prop].append(kwarg_prop)

            properties.update(**kwargs)

        return cls(**properties)


class Environment(DataStoreMixin):
    """Abstract away some of the nasty details of working with STIX content.

    Args:
        factory (ObjectFactory, optional): Factory for creating objects with common
            defaults for certain properties.
        store (DataStore, optional): Data store providing the source and sink for the
            environment.
        source (DataSource, optional): Source for retrieving STIX objects.
        sink (DataSink, optional): Destination for saving STIX objects.
            Invalid if `store` is also provided.

    .. automethod:: get
    .. automethod:: all_versions
    .. automethod:: query
    .. automethod:: creator_of
    .. automethod:: relationships
    .. automethod:: related_to
    .. automethod:: add
    """

    def __init__(self, factory=ObjectFactory(), store=None, source=None, sink=None):
        self.factory = factory
        self.source = CompositeDataSource()
        if store:
            self.source.add_data_source(store.source)
            self.sink = store.sink
        if source:
            self.source.add_data_source(source)
        if sink:
            if store:
                raise ValueError("Data store already provided! Environment may only have one data sink.")
            self.sink = sink

    def create(self, *args, **kwargs):
        return self.factory.create(*args, **kwargs)
    create.__doc__ = ObjectFactory.create.__doc__

    def add_filters(self, *args, **kwargs):
        try:
            return self.source.filters.update(*args, **kwargs)
        except AttributeError:
            raise AttributeError('Environment has no data source')

    def add_filter(self, *args, **kwargs):
        try:
            return self.source.filters.add(*args, **kwargs)
        except AttributeError:
            raise AttributeError('Environment has no data source')

    def parse(self, *args, **kwargs):
        return _parse(*args, **kwargs)
    parse.__doc__ = _parse.__doc__