# https://speakerdeck.com/lig/your-own-orm-in-python-how-and-why
# https://github.com/cyanife/Pyanife/blob/master/orm.py
# https://github.com/mongodb/pymodm/blob/master/pymodm/base/models.py
# https://gist.github.com/fernandojunior/a468b5d7726e978a3e80
# https://github.com/zzzsochi/yadm/tree/master/yadm
# https://docs.mongodb.com/manual/core/index-unique/
from bson import ObjectId
from collections import OrderedDict

"""
user = User.get_queryset(db).order_by('-username').find()

user = User(username='tester', password='test123')
User.save(db, user)
"""


class AttrDict(dict):
  __getattr__ = dict.get
  __setattr__ = dict.__setitem__
  __delattr__ = dict.__delitem__


class MetaDict(AttrDict):
  pass


class Field:
  # [-]<field_name> - минус в начале означает, что поле сортируется в порядке
  # убывания
  # TODO: add unique with

  def __init__(
    self,
    name=None,
    required=False,
    default=None,
    choices=None,
    unique=False,
    unique_with=None,
    primary_key=False,
    null=True,
    **kwargs
  ):
    self.name = name
    self.required = required
    self.default = default
    self.choices = choices
    self.unique = unique
    self.unique_with = unique_with
    self.primary_key = primary_key
    self.null = null

  def __get__(self, instance, owner):
    if instance is None:
      return self
    return instance._data[self.name]

  def __set__(self, instance, value):
    instance._data[self.name] = value
    instance._mark_as_changed(self.name)

  def has_default(self):
    return self.default is not None

  def get_default(self):
    if self.has_default():
      if callable(self.default):
        return self.default()
      return self.default
    return None

  def validate(self, value):
    pass

  def to_python(self, value):
    return value


class ModelMeta(type):

  def __new__(cls, name, bases, attrs):
    fields = OrderedDict()
    for k, v in attrs.items():
      if isinstance(v, Field):
        if v.name is None:
          v.name = k
        fields[k] = v
    attrs['_fields'] = fields
    attrs['_db_fields_map'] = {field.name: field for field in fields.values()}
    return type.__new__(cls, name, bases, attrs)


class QuerySet:
  pass


class Model(metaclass=ModelMeta):

  def __init__(self, *args, **kwargs):
    self._changed = {}

  def _mark_as_changed(self, name):
    self._changed[name] = True

  @classmethod
  def get_queryset(cls, db):
    pass

  @classmethod
  def insert(cls, db, model):
    pass

  @classmethod
  def update(cls, db, model):
    pass

  @classmethod
  def remove(cls, db, model):
    pass


class Test(Model):
  qwe = Field()