from __future__ import annotations

import operator
import typing
from typing import Any
from typing import Callable
from typing import Dict
from typing import Iterator
from typing import List
from typing import Mapping
from typing import Optional
from typing import Tuple
from typing import Type

if typing.TYPE_CHECKING:
    from .result import _KeyType
    from .result import _ProcessorsType
    from .result import _RawRowType
    from .result import _TupleGetterType
    from .result import ResultMetaData

MD_INDEX = 0  # integer index in cursor.description


class BaseRow:
    __slots__ = ("_parent", "_data", "_key_to_index")

    _parent: ResultMetaData
    _key_to_index: Mapping[_KeyType, int]
    _data: _RawRowType

    def __init__(
        self,
        parent: ResultMetaData,
        processors: Optional[_ProcessorsType],
        key_to_index: Mapping[_KeyType, int],
        data: _RawRowType,
    ):
        """Row objects are constructed by CursorResult objects."""
        object.__setattr__(self, "_parent", parent)

        object.__setattr__(self, "_key_to_index", key_to_index)

        if processors:
            object.__setattr__(
                self,
                "_data",
                tuple(
                    [
                        proc(value) if proc else value
                        for proc, value in zip(processors, data)
                    ]
                ),
            )
        else:
            object.__setattr__(self, "_data", tuple(data))

    def __reduce__(self) -> Tuple[Callable[..., BaseRow], Tuple[Any, ...]]:
        return (
            rowproxy_reconstructor,
            (self.__class__, self.__getstate__()),
        )

    def __getstate__(self) -> Dict[str, Any]:
        return {"_parent": self._parent, "_data": self._data}

    def __setstate__(self, state: Dict[str, Any]) -> None:
        parent = state["_parent"]
        object.__setattr__(self, "_parent", parent)
        object.__setattr__(self, "_data", state["_data"])
        object.__setattr__(self, "_key_to_index", parent._key_to_index)

    def _values_impl(self) -> List[Any]:
        return list(self)

    def __iter__(self) -> Iterator[Any]:
        return iter(self._data)

    def __len__(self) -> int:
        return len(self._data)

    def __hash__(self) -> int:
        return hash(self._data)

    def __getitem__(self, key: Any) -> Any:
        return self._data[key]

    def _get_by_key_impl_mapping(self, key: str) -> Any:
        try:
            return self._data[self._key_to_index[key]]
        except KeyError:
            pass
        self._parent._key_not_found(key, False)

    def __getattr__(self, name: str) -> Any:
        try:
            return self._data[self._key_to_index[name]]
        except KeyError:
            pass
        self._parent._key_not_found(name, True)

    def _to_tuple_instance(self) -> Tuple[Any, ...]:
        return self._data


# This reconstructor is necessary so that pickles with the Cy extension or
# without use the same Binary format.
def rowproxy_reconstructor(
    cls: Type[BaseRow], state: Dict[str, Any]
) -> BaseRow:
    obj = cls.__new__(cls)
    obj.__setstate__(state)
    return obj


def tuplegetter(*indexes: int) -> _TupleGetterType:
    if len(indexes) != 1:
        for i in range(1, len(indexes)):
            if indexes[i - 1] != indexes[i] - 1:
                return operator.itemgetter(*indexes)
    # slice form is faster but returns a list if input is list
    return operator.itemgetter(slice(indexes[0], indexes[-1] + 1))
