import copy
import inspect
import json
import uuid
from typing import Any, List, Type, TYPE_CHECKING, Optional, TypeVar, Tuple
from typing import Set, Dict

import pydantic
import sqlalchemy
from pydantic import BaseModel, BaseConfig, create_model

import orm.queryset as qry
from orm.exceptions import ModelDefinitionError
from orm.fields import BaseField, ForeignKey
from orm.relations import RelationshipManager

relationship_manager = RelationshipManager()


def parse_pydantic_field_from_model_fields(object_dict: dict) -> Dict[str, Tuple]:
    pydantic_fields = {field_name: (
        base_field.__type__,
        ... if base_field.is_required else base_field.default_value
    )
        for field_name, base_field in object_dict.items()
        if isinstance(base_field, BaseField)}
    return pydantic_fields


def sqlalchemy_columns_from_model_fields(name: str, object_dict: Dict, tablename: str) -> Tuple[Optional[str],
                                                                                                List[sqlalchemy.Column],
                                                                                                Dict[str, BaseField]]:
    pkname: Optional[str] = None
    columns: List[sqlalchemy.Column] = []
    model_fields: Dict[str, BaseField] = {}

    for field_name, field in object_dict.items():
        if isinstance(field, BaseField):
            model_fields[field_name] = field
            if not field.pydantic_only:
                if field.primary_key:
                    pkname = field_name
                if isinstance(field, ForeignKey):
                    reverse_name = field.related_name or field.to.__name__.title() + '_' + name.lower() + 's'
                    relation_name = name + '_' + field.to.__name__.lower()
                    relationship_manager.add_relation_type(relation_name, reverse_name, field, tablename)
                columns.append(field.get_column(field_name))
    return pkname, columns, model_fields


def get_pydantic_base_orm_config() -> Type[BaseConfig]:
    class Config(BaseConfig):
        orm_mode = True

    return Config


class ModelMetaclass(type):
    def __new__(
            mcs: type, name: str, bases: Any, attrs: dict
    ) -> type:
        new_model = super().__new__(  # type: ignore
            mcs, name, bases, attrs
        )

        if attrs.get("__abstract__"):
            return new_model

        tablename = attrs["__tablename__"]
        metadata = attrs["__metadata__"]

        # sqlalchemy table creation
        pkname, columns, model_fields = sqlalchemy_columns_from_model_fields(name, attrs, tablename)
        attrs['__table__'] = sqlalchemy.Table(tablename, metadata, *columns)
        attrs['__columns__'] = columns
        attrs['__pkname__'] = pkname

        if not pkname:
            raise ModelDefinitionError('Table has to have a primary key.')

        # pydantic model creation
        pydantic_fields = parse_pydantic_field_from_model_fields(attrs)
        pydantic_model = create_model(name, __config__=get_pydantic_base_orm_config(), **pydantic_fields)
        attrs['__pydantic_fields__'] = pydantic_fields
        attrs['__pydantic_model__'] = pydantic_model
        attrs['__fields__'] = copy.deepcopy(pydantic_model.__fields__)
        attrs['__signature__'] = copy.deepcopy(pydantic_model.__signature__)
        attrs['__annotations__'] = copy.deepcopy(pydantic_model.__annotations__)
        attrs['__model_fields__'] = model_fields

        new_model = super().__new__(  # type: ignore
            mcs, name, bases, attrs
        )

        return new_model


class Model(list, metaclass=ModelMetaclass):
    # Model inherits from list in order to be treated as request.Body parameter in fastapi routes,
    # inheriting from pydantic.BaseModel causes metaclass conflicts
    __abstract__ = True
    if TYPE_CHECKING:  # pragma no cover
        __model_fields__: Dict[str, TypeVar[BaseField]]
        __table__: sqlalchemy.Table
        __fields__: Dict[str, pydantic.fields.ModelField]
        __pydantic_model__: Type[BaseModel]
        __pkname__: str

    objects = qry.QuerySet()

    def __init__(self, *args, **kwargs) -> None:
        self._orm_id: str = uuid.uuid4().hex
        self._orm_saved: bool = False
        self._orm_relationship_manager: RelationshipManager = relationship_manager
        self.values: Optional[BaseModel] = None

        if "pk" in kwargs:
            kwargs[self.__pkname__] = kwargs.pop("pk")
        kwargs = {k: self.__model_fields__[k].expand_relationship(v, self) for k, v in kwargs.items()}
        self.values = self.__pydantic_model__(**kwargs)

    def __del__(self):
        self._orm_relationship_manager.deregister(self)

    def __setattr__(self, key: str, value: Any) -> None:
        if key in self.__fields__:
            if self.is_conversion_to_json_needed(key) and not isinstance(value, str):
                try:
                    value = json.dumps(value)
                except TypeError:  # pragma no cover
                    pass
            value = self.__model_fields__[key].expand_relationship(value, self)
            setattr(self.values, key, value)
        else:
            super().__setattr__(key, value)

    def __getattribute__(self, key: str) -> Any:
        if key != '__fields__' and key in self.__fields__:
            relation_key = self.__class__.__name__.title() + '_' + key
            if self._orm_relationship_manager.contains(relation_key, self):
                return self._orm_relationship_manager.get(relation_key, self)

            item = getattr(self.values, key, None)
            if item is not None and self.is_conversion_to_json_needed(key) and isinstance(item, str):
                try:
                    item = json.loads(item)
                except TypeError:  # pragma no cover
                    pass
            return item
        return super().__getattribute__(key)

    def __eq__(self, other):
        return self.values.dict() == other.values.dict()

    def __repr__(self):  # pragma no cover
        return self.values.__repr__()

    @classmethod
    def from_row(cls, row, select_related: List = None) -> 'Model':
        item = {}
        select_related = select_related or []
        for related in select_related:
            if "__" in related:
                first_part, remainder = related.split("__", 1)
                model_cls = cls.__model_fields__[first_part].to
                item[first_part] = model_cls.from_row(row, select_related=[remainder])
            else:
                model_cls = cls.__model_fields__[related].to
                item[related] = model_cls.from_row(row)

        for column in cls.__table__.columns:
            if column.name not in item:
                item[column.name] = row[column]

        return cls(**item)

    # @classmethod
    # def validate(cls, value: Any) -> 'BaseModel':  # pragma no cover
    #     return cls.__pydantic_model__.validate(value=value)

    @classmethod
    def __get_validators__(cls):  # pragma no cover
        yield cls.__pydantic_model__.validate

    # @classmethod
    # def schema(cls, by_alias: bool = True):  # pragma no cover
    #     return cls.__pydantic_model__.schema(by_alias=by_alias)

    def is_conversion_to_json_needed(self, column_name: str) -> bool:
        return self.__model_fields__.get(column_name).__type__ == pydantic.Json

    @property
    def pk(self):
        return getattr(self.values, self.__pkname__)

    @pk.setter
    def pk(self, value):
        setattr(self.values, self.__pkname__, value)

    @property
    def pk_column(self) -> sqlalchemy.Column:
        return self.__table__.primary_key.columns.values()[0]

    def dict(self) -> Dict:
        return self.values.dict()

    def from_dict(self, value_dict: Dict) -> None:
        for key, value in value_dict.items():
            setattr(self, key, value)

    def extract_own_model_fields(self) -> Dict:
        related_names = self.extract_related_names()
        self_fields = {k: v for k, v in self.dict().items() if k not in related_names}
        return self_fields

    @classmethod
    def extract_related_names(cls) -> Set:
        related_names = set()
        for name, field in cls.__fields__.items():
            if inspect.isclass(field.type_) and issubclass(field.type_, pydantic.BaseModel):
                related_names.add(name)
        return related_names

    def extract_model_db_fields(self) -> Dict:
        self_fields = self.extract_own_model_fields()
        self_fields = {k: v for k, v in self_fields.items() if k in self.__table__.columns}
        for field in self.extract_related_names():
            if getattr(self, field) is not None:
                self_fields[field] = getattr(getattr(self, field), self.__model_fields__[field].to.__pkname__)
        return self_fields

    async def save(self) -> int:
        self_fields = self.extract_model_db_fields()
        if self.__model_fields__.get(self.__pkname__).autoincrement:
            self_fields.pop(self.__pkname__, None)
        expr = self.__table__.insert()
        expr = expr.values(**self_fields)
        item_id = await self.__database__.execute(expr)
        setattr(self, 'pk', item_id)
        return item_id

    async def update(self, **kwargs: Any) -> int:
        if kwargs:
            new_values = {**self.dict(), **kwargs}
            self.from_dict(new_values)

        self_fields = self.extract_model_db_fields()
        self_fields.pop(self.__pkname__)
        expr = self.__table__.update().values(**self_fields).where(
            self.pk_column == getattr(self, self.__pkname__))
        result = await self.__database__.execute(expr)
        return result

    async def delete(self) -> int:
        expr = self.__table__.delete()
        expr = expr.where(self.pk_column == (getattr(self, self.__pkname__)))
        result = await self.__database__.execute(expr)
        return result

    async def load(self) -> 'Model':
        expr = self.__table__.select().where(self.pk_column == self.pk)
        row = await self.__database__.fetch_one(expr)
        self.from_dict(dict(row))
        return self