from deepmerge import Merger, STRATEGY_END
from django.db.models.signals import class_prepared
from django.utils.functional import curry
from django_fsm import (
    FSMFieldMixin,
    get_all_FIELD_transitions,
    get_available_FIELD_transitions,
    get_available_user_FIELD_transitions,
)
from rest_framework.request import _hasattr, is_form_media_type, Request

__all__ = ["patches"]


def merge_dicts(config, path, base, nxt):
    if isinstance(base, list) and isinstance(nxt, list) and len(base) == len(nxt):
        data = [{**a, **b} for a, b in zip(base, nxt)]
        return data
    return STRATEGY_END


merger = Merger(
    [(list, merge_dicts), (list, "append"), (dict, "merge")], ["override"], ["override"]
)


def _patched_load_data_and_files(self):
    """
    Parses the request content into `self.data`.
    """
    if not _hasattr(self, "_data"):
        self._data, self._files = self._parse()
        if self._files:
            self._full_data = merger.merge(self._data, self._files)
        else:
            self._full_data = self._data

        # if a form media type, copy data & files refs to the underlying
        # http request so that closable objects are handled appropriately.
        if is_form_media_type(self.content_type):
            self._request._post = self.POST
            self._request._files = self.FILES


def _modified_contribute_to_class(self, cls, name, **kwargs):
    self.base_cls = cls

    super(FSMFieldMixin, self).contribute_to_class(cls, name, **kwargs)
    setattr(cls, f"{self.name}_description", self.descriptor_class(self))
    setattr(
        cls,
        "get_all_{0}_transitions".format(self.name),
        curry(get_all_FIELD_transitions, field=self),
    )
    setattr(
        cls,
        "get_available_{0}_transitions".format(self.name),
        curry(get_available_FIELD_transitions, field=self),
    )
    setattr(
        cls,
        "get_available_user_{0}_transitions".format(self.name),
        curry(get_available_user_FIELD_transitions, field=self),
    )
    class_prepared.connect(self._collect_transitions)


# Do not obscure related model in FSMKeyField
# Pull request https://github.com/viewflow/django-fsm/pull/200/files#diff-7b4b9604f1842ff54833d14e644e9710


class Patches:
    def __init__(self):
        self._load_data_and_files = None
        self._contribute_to_class = None

    def on(self):
        self._load_data_and_files = Request._load_data_and_files
        self._contribute_to_class = FSMFieldMixin.contribute_to_class

        Request._load_data_and_files = _patched_load_data_and_files
        FSMFieldMixin.contribute_to_class = _modified_contribute_to_class

    def off(self):
        if self._load_data_and_files:
            Request._load_data_and_files = self._load_data_and_files
        if self._contribute_to_class:
            FSMFieldMixin.contribute_to_class = self._contribute_to_class


patches = Patches()