"""
Python STIX 2.0 Memory Source/Sink
"""

import io
import itertools
import json
import os

from stix2 import v20, v21
from stix2.base import _STIXBase
from stix2.core import parse
from stix2.datastore import DataSink, DataSource, DataStoreMixin
from stix2.datastore.filters import FilterSet, apply_common_filters


def _add(store, stix_data, allow_custom=True, version=None):
    """Add STIX objects to MemoryStore/Sink.

    Adds STIX objects to an in-memory dictionary for fast lookup.
    Recursive function, breaks down STIX Bundles and lists.

    Args:
        store: A MemoryStore, MemorySink or MemorySource object.
        stix_data (list OR dict OR STIX object): STIX objects to be added
        allow_custom (bool): Whether to allow custom properties as well unknown
            custom objects. Note that unknown custom objects cannot be parsed
            into STIX objects, and will be returned as is. Default: False.
        version (str): Which STIX2 version to lock the parser to. (e.g. "2.0",
            "2.1"). If None, the library makes the best effort to figure
            out the spec representation of the object.

    """
    if isinstance(stix_data, list):
        # STIX objects are in a list- recurse on each object
        for stix_obj in stix_data:
            _add(store, stix_obj, allow_custom, version)

    elif stix_data["type"] == "bundle":
        # adding a json bundle - so just grab STIX objects
        for stix_obj in stix_data.get("objects", []):
            _add(store, stix_obj, allow_custom, version)

    else:
        # Adding a single non-bundle object
        if isinstance(stix_data, _STIXBase):
            stix_obj = stix_data
        else:
            stix_obj = parse(stix_data, allow_custom, version)

        # Map ID directly to the object, if it is a marking.  Otherwise,
        # map to a family, so we can track multiple versions.
        if _is_marking(stix_obj):
            store._data[stix_obj["id"]] = stix_obj

        else:
            if stix_obj["id"] in store._data:
                obj_family = store._data[stix_obj["id"]]
            else:
                obj_family = _ObjectFamily()
                store._data[stix_obj["id"]] = obj_family

            obj_family.add(stix_obj)


def _is_marking(obj_or_id):
    """Determines whether the given object or object ID is/is for a marking
    definition.

    :param obj_or_id: A STIX object or object ID as a string.
    :return: True if a marking definition, False otherwise.
    """

    if isinstance(obj_or_id, (_STIXBase, dict)):
        id_ = obj_or_id["id"]
    else:
        id_ = obj_or_id

    return id_.startswith("marking-definition--")


class _ObjectFamily(object):
    """
    An internal implementation detail of memory sources/sinks/stores.
    Represents a "family" of STIX objects: all objects with a particular
    ID.  (I.e. all versions.)  The latest version is also tracked so that it
    can be obtained quickly.
    """
    def __init__(self):
        self.all_versions = {}
        self.latest_version = None

    def add(self, obj):
        self.all_versions[obj["modified"]] = obj
        if self.latest_version is None or \
                obj["modified"] > self.latest_version["modified"]:
            self.latest_version = obj

    def __str__(self):
        return "<<{}; latest={}>>".format(
            self.all_versions,
            self.latest_version["modified"],
        )

    def __repr__(self):
        return str(self)


class MemoryStore(DataStoreMixin):
    """Interface to an in-memory dictionary of STIX objects.

    MemoryStore is a wrapper around a paired MemorySink and MemorySource.

    Note: It doesn't make sense to create a MemoryStore by passing
    in existing MemorySource and MemorySink because there could
    be data concurrency issues. As well, just as easy to create new MemoryStore.

    Args:
        stix_data (list OR dict OR STIX object): STIX content to be added
        allow_custom (bool): whether to allow custom STIX content.
            Only applied when export/input functions called, i.e.
            load_from_file() and save_to_file(). Defaults to True.

    Attributes:
        _data (dict): the in-memory dict that holds STIX objects
        source (MemorySource): MemorySource
        sink (MemorySink): MemorySink

    """
    def __init__(self, stix_data=None, allow_custom=True):
        self._data = {}

        if stix_data:
            _add(self, stix_data, allow_custom)

        super(MemoryStore, self).__init__(
            source=MemorySource(stix_data=self._data, allow_custom=allow_custom, _store=True),
            sink=MemorySink(stix_data=self._data, allow_custom=allow_custom, _store=True),
        )

    def save_to_file(self, *args, **kwargs):
        """Write SITX objects from in-memory dictionary to JSON file, as a STIX
        Bundle. If a directory is given, the Bundle 'id' will be used as
        filename. Otherwise, the provided value will be used.

        Args:
            path (str): file path to write STIX data to.
            encoding (str): The file encoding. Default utf-8.

        """
        return self.sink.save_to_file(*args, **kwargs)

    def load_from_file(self, *args, **kwargs):
        """Load STIX data from JSON file.

        File format is expected to be a single JSON STIX object or JSON STIX
        bundle.

        Args:
            path (str): file path to load STIX data from

        """
        return self.source.load_from_file(*args, **kwargs)


class MemorySink(DataSink):
    """Interface for adding/pushing STIX objects to an in-memory dictionary.

    Designed to be paired with a MemorySource, together as the two
    components of a MemoryStore.

    Args:
        stix_data (dict OR list): valid STIX 2.0 content in
            bundle or a list.
        _store (bool): whether the MemorySink is a part of a MemoryStore,
            in which case "stix_data" is a direct reference to
            shared memory with DataSource. Not user supplied
        allow_custom (bool): whether to allow custom objects/properties
            when exporting STIX content to file.
            Default: True.

    Attributes:
        _data (dict): the in-memory dict that holds STIX objects.
            If part of a MemoryStore, the dict is shared with a MemorySource

    """
    def __init__(self, stix_data=None, allow_custom=True, _store=False):
        super(MemorySink, self).__init__()
        self.allow_custom = allow_custom

        if _store:
            self._data = stix_data
        else:
            self._data = {}
            if stix_data:
                _add(self, stix_data, allow_custom)

    def add(self, stix_data):
        _add(self, stix_data, self.allow_custom)
    add.__doc__ = _add.__doc__

    def save_to_file(self, path, encoding="utf-8"):
        path = os.path.abspath(path)

        all_objs = list(itertools.chain.from_iterable(
            value.all_versions.values() if isinstance(value, _ObjectFamily)
            else [value]
            for value in self._data.values()
        ))

        if any("spec_version" in x for x in all_objs):
            bundle = v21.Bundle(all_objs, allow_custom=self.allow_custom)
        else:
            bundle = v20.Bundle(all_objs, allow_custom=self.allow_custom)

        if not os.path.exists(os.path.dirname(path)):
            os.makedirs(os.path.dirname(path))

        # if the user only provided a directory, use the bundle id for filename
        if os.path.isdir(path):
            path = os.path.join(path, bundle["id"] + ".json")

        with io.open(path, "w", encoding=encoding) as f:
            bundle = bundle.serialize(pretty=True, encoding=encoding, ensure_ascii=False)
            f.write(bundle)
    save_to_file.__doc__ = MemoryStore.save_to_file.__doc__


class MemorySource(DataSource):
    """Interface for searching/retrieving STIX objects from an in-memory
    dictionary.

    Designed to be paired with a MemorySink, together as the two
    components of a MemoryStore.

    Args:
        stix_data (dict OR list OR STIX object): valid STIX 2.0 content in
            bundle or list.
        _store (bool): if the MemorySource is a part of a MemoryStore,
            in which case "stix_data" is a direct reference to shared
            memory with DataSink. Not user supplied
        allow_custom (bool): whether to allow custom objects/properties
            when importing STIX content from file.
            Default: True.

    Attributes:
        _data (dict): the in-memory dict that holds STIX objects.
            If part of a MemoryStore, the dict is shared with a MemorySink

    """
    def __init__(self, stix_data=None, allow_custom=True, _store=False):
        super(MemorySource, self).__init__()
        self.allow_custom = allow_custom

        if _store:
            self._data = stix_data
        else:
            self._data = {}
            if stix_data:
                _add(self, stix_data, allow_custom)

    def get(self, stix_id, _composite_filters=None):
        """Retrieve STIX object from in-memory dict via STIX ID.

        Args:
            stix_id (str): The STIX ID of the STIX object to be retrieved.
            _composite_filters (FilterSet): collection of filters passed from the parent
                CompositeDataSource, not user supplied

        Returns:
            (STIX object): STIX object that has the supplied ID.

        """
        stix_obj = None

        if _is_marking(stix_id):
            stix_obj = self._data.get(stix_id)
        else:
            object_family = self._data.get(stix_id)
            if object_family:
                stix_obj = object_family.latest_version

        if stix_obj:
            all_filters = list(
                itertools.chain(
                    _composite_filters or [],
                    self.filters,
                ),
            )

            stix_obj = next(apply_common_filters([stix_obj], all_filters), None)

        return stix_obj

    def all_versions(self, stix_id, _composite_filters=None):
        """Retrieve STIX objects from in-memory dict via STIX ID, all versions
        of it.

        Note: Since Memory sources/sinks don't handle multiple versions of a
        STIX object, this operation is unnecessary. Translate call to get().

        Args:
            stix_id (str): The STIX ID of the STIX 2 object to retrieve.
            _composite_filters (FilterSet): collection of filters passed from
                the parent CompositeDataSource, not user supplied

        Returns:
            (list): list of STIX objects that have the supplied ID.

        """
        results = []
        stix_objs_to_filter = None
        if _is_marking(stix_id):
            stix_obj = self._data.get(stix_id)
            if stix_obj:
                stix_objs_to_filter = [stix_obj]
        else:
            object_family = self._data.get(stix_id)
            if object_family:
                stix_objs_to_filter = object_family.all_versions.values()

        if stix_objs_to_filter:
            all_filters = list(
                itertools.chain(
                    _composite_filters or [],
                    self.filters,
                ),
            )

            results.extend(
                apply_common_filters(stix_objs_to_filter, all_filters),
            )

        return results

    def query(self, query=None, _composite_filters=None):
        """Search and retrieve STIX objects based on the complete query.

        A "complete query" includes the filters from the query, the filters
        attached to this MemorySource, and any filters passed from a
        CompositeDataSource (i.e. _composite_filters).

        Args:
            query (list): list of filters to search on
            _composite_filters (FilterSet): collection of filters passed from
                the CompositeDataSource, not user supplied

        Returns:
            (list): list of STIX objects that match the supplied query.

        """
        query = FilterSet(query)

        # combine all query filters
        if self.filters:
            query.add(self.filters)
        if _composite_filters:
            query.add(_composite_filters)

        all_objs = itertools.chain.from_iterable(
            value.all_versions.values() if isinstance(value, _ObjectFamily)
            else [value]
            for value in self._data.values()
        )

        # Apply STIX common property filters.
        all_data = list(apply_common_filters(all_objs, query))

        return all_data

    def load_from_file(self, file_path):
        with open(os.path.abspath(file_path), "r") as f:
            stix_data = json.load(f)

        _add(self, stix_data, self.allow_custom)
    load_from_file.__doc__ = MemoryStore.load_from_file.__doc__