"""Almost entirely complete, generic `selectors` implementation."""

from __future__ import annotations

import re
from functools import partial
from typing import TYPE_CHECKING
from typing import Any
from typing import Collection
from typing import Iterable
from typing import Iterator
from typing import Protocol
from typing import Sequence
from typing import TypeVar
from typing import overload

from narwhals._compliant.expr import CompliantExpr
from narwhals.utils import _parse_time_unit_and_time_zone
from narwhals.utils import dtype_matches_time_unit_and_time_zone
from narwhals.utils import get_column_names
from narwhals.utils import is_compliant_dataframe

if not TYPE_CHECKING:  # pragma: no cover
    # TODO @dangotbanned: Remove after dropping `3.8` (#2084)
    # - https://github.com/narwhals-dev/narwhals/pull/2064#discussion_r1965921386
    import sys

    if sys.version_info >= (3, 9):
        from typing import Protocol as Protocol38
    else:
        from typing import Generic as Protocol38

else:  # pragma: no cover
    from typing import Protocol as Protocol38

if TYPE_CHECKING:
    from datetime import timezone

    from typing_extensions import Self
    from typing_extensions import TypeAlias
    from typing_extensions import TypeIs

    from narwhals._compliant.expr import NativeExpr
    from narwhals._compliant.typing import CompliantDataFrameAny
    from narwhals._compliant.typing import CompliantExprAny
    from narwhals._compliant.typing import CompliantFrameAny
    from narwhals._compliant.typing import CompliantLazyFrameAny
    from narwhals._compliant.typing import CompliantSeriesAny
    from narwhals._compliant.typing import CompliantSeriesOrNativeExprAny
    from narwhals._compliant.typing import EvalNames
    from narwhals._compliant.typing import EvalSeries
    from narwhals.dtypes import DType
    from narwhals.typing import TimeUnit
    from narwhals.utils import Implementation
    from narwhals.utils import Version
    from narwhals.utils import _FullContext

__all__ = [
    "CompliantSelector",
    "CompliantSelectorNamespace",
    "EagerSelectorNamespace",
    "LazySelectorNamespace",
]


SeriesOrExprT = TypeVar("SeriesOrExprT", bound="CompliantSeriesOrNativeExprAny")
SeriesT = TypeVar("SeriesT", bound="CompliantSeriesAny")
ExprT = TypeVar("ExprT", bound="NativeExpr")
FrameT = TypeVar("FrameT", bound="CompliantFrameAny")
DataFrameT = TypeVar("DataFrameT", bound="CompliantDataFrameAny")
LazyFrameT = TypeVar("LazyFrameT", bound="CompliantLazyFrameAny")
SelectorOrExpr: TypeAlias = (
    "CompliantSelector[FrameT, SeriesOrExprT] | CompliantExpr[FrameT, SeriesOrExprT]"
)


class CompliantSelectorNamespace(Protocol[FrameT, SeriesOrExprT]):
    _implementation: Implementation
    _backend_version: tuple[int, ...]
    _version: Version

    @classmethod
    def from_namespace(cls, context: _FullContext, /) -> Self:
        obj = cls.__new__(cls)
        obj._implementation = context._implementation
        obj._backend_version = context._backend_version
        obj._version = context._version
        return obj

    @property
    def _selector(self) -> type[CompliantSelector[FrameT, SeriesOrExprT]]: ...

    def _iter_columns(self, df: FrameT, /) -> Iterator[SeriesOrExprT]: ...

    def _iter_schema(self, df: FrameT, /) -> Iterator[tuple[str, DType]]: ...

    def _iter_columns_dtypes(
        self, df: FrameT, /
    ) -> Iterator[tuple[SeriesOrExprT, DType]]: ...

    def _iter_columns_names(self, df: FrameT, /) -> Iterator[tuple[SeriesOrExprT, str]]:
        yield from zip(self._iter_columns(df), df.columns)

    def _is_dtype(
        self: CompliantSelectorNamespace[FrameT, SeriesOrExprT], dtype: type[DType], /
    ) -> CompliantSelector[FrameT, SeriesOrExprT]:
        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            return [
                ser for ser, tp in self._iter_columns_dtypes(df) if isinstance(tp, dtype)
            ]

        def names(df: FrameT) -> Sequence[str]:
            return [name for name, tp in self._iter_schema(df) if isinstance(tp, dtype)]

        return self._selector.from_callables(series, names, context=self)

    def by_dtype(
        self, dtypes: Collection[DType | type[DType]]
    ) -> CompliantSelector[FrameT, SeriesOrExprT]:
        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            return [ser for ser, tp in self._iter_columns_dtypes(df) if tp in dtypes]

        def names(df: FrameT) -> Sequence[str]:
            return [name for name, tp in self._iter_schema(df) if tp in dtypes]

        return self._selector.from_callables(series, names, context=self)

    def matches(self, pattern: str) -> CompliantSelector[FrameT, SeriesOrExprT]:
        p = re.compile(pattern)

        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            if is_compliant_dataframe(df) and not self._implementation.is_duckdb():
                return [df.get_column(col) for col in df.columns if p.search(col)]

            return [ser for ser, name in self._iter_columns_names(df) if p.search(name)]

        def names(df: FrameT) -> Sequence[str]:
            return [col for col in df.columns if p.search(col)]

        return self._selector.from_callables(series, names, context=self)

    def numeric(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            return [ser for ser, tp in self._iter_columns_dtypes(df) if tp.is_numeric()]

        def names(df: FrameT) -> Sequence[str]:
            return [name for name, tp in self._iter_schema(df) if tp.is_numeric()]

        return self._selector.from_callables(series, names, context=self)

    def categorical(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        return self._is_dtype(self._version.dtypes.Categorical)

    def string(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        return self._is_dtype(self._version.dtypes.String)

    def boolean(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        return self._is_dtype(self._version.dtypes.Boolean)

    def all(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            return list(self._iter_columns(df))

        return self._selector.from_callables(series, get_column_names, context=self)

    def datetime(
        self,
        time_unit: TimeUnit | Iterable[TimeUnit] | None,
        time_zone: str | timezone | Iterable[str | timezone | None] | None,
    ) -> CompliantSelector[FrameT, SeriesOrExprT]:
        time_units, time_zones = _parse_time_unit_and_time_zone(time_unit, time_zone)
        matches = partial(
            dtype_matches_time_unit_and_time_zone,
            dtypes=self._version.dtypes,
            time_units=time_units,
            time_zones=time_zones,
        )

        def series(df: FrameT) -> Sequence[SeriesOrExprT]:
            return [ser for ser, tp in self._iter_columns_dtypes(df) if matches(tp)]

        def names(df: FrameT) -> Sequence[str]:
            return [name for name, tp in self._iter_schema(df) if matches(tp)]

        return self._selector.from_callables(series, names, context=self)


class EagerSelectorNamespace(
    CompliantSelectorNamespace[DataFrameT, SeriesT], Protocol[DataFrameT, SeriesT]
):
    def _iter_schema(self, df: DataFrameT, /) -> Iterator[tuple[str, DType]]:
        for ser in self._iter_columns(df):
            yield ser.name, ser.dtype

    def _iter_columns(self, df: DataFrameT, /) -> Iterator[SeriesT]:
        yield from df.iter_columns()

    def _iter_columns_dtypes(self, df: DataFrameT, /) -> Iterator[tuple[SeriesT, DType]]:
        for ser in self._iter_columns(df):
            yield ser, ser.dtype


class LazySelectorNamespace(
    CompliantSelectorNamespace[LazyFrameT, ExprT], Protocol[LazyFrameT, ExprT]
):
    def _iter_schema(self, df: LazyFrameT) -> Iterator[tuple[str, DType]]:
        yield from df.schema.items()

    def _iter_columns(self, df: LazyFrameT) -> Iterator[ExprT]:
        yield from df._iter_columns()

    def _iter_columns_dtypes(self, df: LazyFrameT, /) -> Iterator[tuple[ExprT, DType]]:
        yield from zip(self._iter_columns(df), df.schema.values())


class CompliantSelector(
    CompliantExpr[FrameT, SeriesOrExprT], Protocol38[FrameT, SeriesOrExprT]
):
    _call: EvalSeries[FrameT, SeriesOrExprT]
    _function_name: str
    _depth: int
    _implementation: Implementation
    _backend_version: tuple[int, ...]
    _version: Version
    _call_kwargs: dict[str, Any]

    @classmethod
    def from_callables(
        cls,
        call: EvalSeries[FrameT, SeriesOrExprT],
        evaluate_output_names: EvalNames[FrameT],
        *,
        context: _FullContext,
    ) -> Self:
        obj = cls.__new__(cls)
        obj._call = call
        obj._depth = 0
        obj._function_name = "selector"
        obj._evaluate_output_names = evaluate_output_names
        obj._alias_output_names = None
        obj._implementation = context._implementation
        obj._backend_version = context._backend_version
        obj._version = context._version
        obj._call_kwargs = {}
        return obj

    @property
    def selectors(self) -> CompliantSelectorNamespace[FrameT, SeriesOrExprT]:
        return self.__narwhals_namespace__().selectors

    def _to_expr(self) -> CompliantExpr[FrameT, SeriesOrExprT]: ...

    def _is_selector(
        self, other: Self | CompliantExpr[FrameT, SeriesOrExprT]
    ) -> TypeIs[CompliantSelector[FrameT, SeriesOrExprT]]:
        return isinstance(other, type(self))

    @overload
    def __sub__(self, other: Self) -> Self: ...
    @overload
    def __sub__(
        self, other: CompliantExpr[FrameT, SeriesOrExprT]
    ) -> CompliantExpr[FrameT, SeriesOrExprT]: ...
    def __sub__(
        self, other: SelectorOrExpr[FrameT, SeriesOrExprT]
    ) -> SelectorOrExpr[FrameT, SeriesOrExprT]:
        if self._is_selector(other):

            def series(df: FrameT) -> Sequence[SeriesOrExprT]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [
                    x for x, name in zip(self(df), lhs_names) if name not in rhs_names
                ]

            def names(df: FrameT) -> Sequence[str]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [x for x in lhs_names if x not in rhs_names]

            return self.selectors._selector.from_callables(series, names, context=self)
        return self._to_expr() - other

    @overload
    def __or__(self, other: Self) -> Self: ...
    @overload
    def __or__(
        self, other: CompliantExpr[FrameT, SeriesOrExprT]
    ) -> CompliantExpr[FrameT, SeriesOrExprT]: ...
    def __or__(
        self, other: SelectorOrExpr[FrameT, SeriesOrExprT]
    ) -> SelectorOrExpr[FrameT, SeriesOrExprT]:
        if self._is_selector(other):

            def series(df: FrameT) -> Sequence[SeriesOrExprT]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [
                    *(x for x, name in zip(self(df), lhs_names) if name not in rhs_names),
                    *other(df),
                ]

            def names(df: FrameT) -> Sequence[str]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [*(x for x in lhs_names if x not in rhs_names), *rhs_names]

            return self.selectors._selector.from_callables(series, names, context=self)
        return self._to_expr() | other

    @overload
    def __and__(self, other: Self) -> Self: ...
    @overload
    def __and__(
        self, other: CompliantExpr[FrameT, SeriesOrExprT]
    ) -> CompliantExpr[FrameT, SeriesOrExprT]: ...
    def __and__(
        self, other: SelectorOrExpr[FrameT, SeriesOrExprT]
    ) -> SelectorOrExpr[FrameT, SeriesOrExprT]:
        if self._is_selector(other):

            def series(df: FrameT) -> Sequence[SeriesOrExprT]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [x for x, name in zip(self(df), lhs_names) if name in rhs_names]

            def names(df: FrameT) -> Sequence[str]:
                lhs_names, rhs_names = _eval_lhs_rhs(df, self, other)
                return [x for x in lhs_names if x in rhs_names]

            return self.selectors._selector.from_callables(series, names, context=self)
        return self._to_expr() & other

    def __invert__(self) -> CompliantSelector[FrameT, SeriesOrExprT]:
        return self.selectors.all() - self


def _eval_lhs_rhs(
    df: CompliantFrameAny, lhs: CompliantExprAny, rhs: CompliantExprAny
) -> tuple[Sequence[str], Sequence[str]]:
    return lhs._evaluate_output_names(df), rhs._evaluate_output_names(df)