import importlib
import pkgutil

import stix2

from .exceptions import ParseError
from .utils import _get_dict

STIX2_OBJ_MAPS = {}


def parse(data, allow_custom=False, version=None):
    """Convert a string, dict or file-like object into a STIX object.

    Args:
        data (str, dict, file-like object): The STIX 2 content to be parsed.
        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): Only used for bundles.  If the spec_version property is
            missing, it is ambiguous what spec should be used to parse the
            bundle.  In this case, this version parameter gives the spec
            version to use.

    Returns:
        An instantiated Python STIX object.

    Warnings:
        'allow_custom=True' will allow for the return of any supplied STIX
        dict(s) that cannot be found to map to any known STIX object types
        (both STIX2 domain objects or defined custom STIX2 objects); NO
        validation is done. This is done to allow the processing of possibly
        unknown custom STIX objects (example scenario: I need to query a
        third-party TAXII endpoint that could provide custom STIX objects that
        I don't know about ahead of time)

    """
    # convert STIX object to dict, if not already
    obj = _get_dict(data)

    # convert dict to full python-stix2 obj
    obj = dict_to_stix2(obj, allow_custom, version)

    return obj


def dict_to_stix2(stix_dict, allow_custom=False, version=None):
    """convert dictionary to full python-stix2 object

        Args:
            stix_dict (dict): a python dictionary of a STIX object
                that (presumably) is semantically correct to be parsed
                into a full python-stix2 obj
            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: Only used for bundles.  If the spec_version property is
                missing, it is ambiguous what spec should be used to parse the
                bundle.  In this case, this version parameter gives the spec
                version to use.

        Returns:
            An instantiated Python STIX object

        Warnings:
            'allow_custom=True' will allow for the return of any supplied STIX
            dict(s) that cannot be found to map to any known STIX object types
            (both STIX2 domain objects or defined custom STIX2 objects); NO
            validation is done. This is done to allow the processing of
            possibly unknown custom STIX objects (example scenario: I need to
            query a third-party TAXII endpoint that could provide custom STIX
            objects that I don't know about ahead of time)

    """
    if 'type' not in stix_dict:
        raise ParseError("Can't parse object with no 'type' property: %s" % str(stix_dict))

    if 'spec_version' in stix_dict:
        # For STIX 2.0, applies to bundles only.
        # For STIX 2.1+, applies to SDOs, SROs, and markings only.
        v = 'v' + stix_dict['spec_version'].replace('.', '')
    elif stix_dict['type'] == 'bundle':
        # bundles without spec_version are ambiguous.
        if version:
            v = 'v' + version.replace('.', '')
        else:
            v = 'v' + stix2.DEFAULT_VERSION.replace('.', '')
    else:
        v = 'v' + stix2.DEFAULT_VERSION.replace('.', '')

    OBJ_MAP = STIX2_OBJ_MAPS[v]

    try:
        obj_class = OBJ_MAP[stix_dict['type']]
    except KeyError:
        if allow_custom:
            # flag allows for unknown custom objects too, but will not
            # be parsed into STIX object, returned as is
            return stix_dict
        raise ParseError("Can't parse unknown object type '%s'! For custom types, use the CustomObject decorator." % stix_dict['type'])

    return obj_class(allow_custom=allow_custom, **stix_dict)


def _register_type(new_type, version=None):
    """Register a custom STIX Object type.

    Args:
        new_type (class): A class to register in the Object map.
        version (str): Which STIX2 version to use. (e.g. "2.0", "2.1"). If
            None, use latest version.
    """
    if not version:
        # Use latest version
        v = 'v' + stix2.DEFAULT_VERSION.replace('.', '')
    else:
        v = 'v' + version.replace('.', '')

    OBJ_MAP = STIX2_OBJ_MAPS[v]
    OBJ_MAP[new_type._type] = new_type


def _collect_stix2_obj_maps():
    """Navigate the package once and retrieve all OBJ_MAP dicts for each v2X
    package."""
    if not STIX2_OBJ_MAPS:
        top_level_module = importlib.import_module('stix2')
        path = top_level_module.__path__
        prefix = str(top_level_module.__name__) + '.'

        for module_loader, name, is_pkg in pkgutil.walk_packages(path=path,
                                                                 prefix=prefix):
            if name.startswith('stix2.v2') and is_pkg:
                mod = importlib.import_module(name, str(top_level_module.__name__))
                STIX2_OBJ_MAPS[name.split('.')[-1]] = mod.OBJ_MAP