from __future__ import annotations

from typing import TYPE_CHECKING
from typing import Any
from typing import Iterable
from typing import Iterator
from typing import Mapping
from typing import Sequence
from typing import cast
from typing import overload

import polars as pl

from narwhals._polars.utils import catch_polars_exception
from narwhals._polars.utils import extract_args_kwargs
from narwhals._polars.utils import extract_native
from narwhals._polars.utils import narwhals_to_native_dtype
from narwhals._polars.utils import native_to_narwhals_dtype
from narwhals.dependencies import is_numpy_array_1d
from narwhals.utils import Implementation
from narwhals.utils import requires
from narwhals.utils import validate_backend_version

if TYPE_CHECKING:
    from types import ModuleType
    from typing import TypeVar

    import pandas as pd
    from typing_extensions import Self
    from typing_extensions import TypeIs

    from narwhals._arrow.typing import ArrowArray
    from narwhals._polars.dataframe import Method
    from narwhals._polars.dataframe import PolarsDataFrame
    from narwhals._polars.expr import PolarsExpr
    from narwhals._polars.namespace import PolarsNamespace
    from narwhals.dtypes import DType
    from narwhals.typing import Into1DArray
    from narwhals.typing import MultiIndexSelector
    from narwhals.typing import _1DArray
    from narwhals.utils import Version
    from narwhals.utils import _FullContext

    T = TypeVar("T")


class PolarsSeries:
    def __init__(
        self,
        series: pl.Series,
        *,
        backend_version: tuple[int, ...],
        version: Version,
    ) -> None:
        self._native_series: pl.Series = series
        self._backend_version = backend_version
        self._implementation = Implementation.POLARS
        self._version = version
        validate_backend_version(self._implementation, self._backend_version)

    def __repr__(self) -> str:  # pragma: no cover
        return "PolarsSeries"

    def __narwhals_namespace__(self) -> PolarsNamespace:
        from narwhals._polars.namespace import PolarsNamespace

        return PolarsNamespace(
            backend_version=self._backend_version, version=self._version
        )

    def __narwhals_series__(self) -> Self:
        return self

    def __native_namespace__(self) -> ModuleType:
        if self._implementation is Implementation.POLARS:
            return self._implementation.to_native_namespace()

        msg = f"Expected polars, got: {type(self._implementation)}"  # pragma: no cover
        raise AssertionError(msg)

    def _with_version(self, version: Version) -> Self:
        return self.__class__(
            self.native, backend_version=self._backend_version, version=version
        )

    @classmethod
    def from_iterable(
        cls,
        data: Iterable[Any],
        *,
        context: _FullContext,
        name: str = "",
        dtype: DType | type[DType] | None = None,
    ) -> Self:
        version = context._version
        backend_version = context._backend_version
        dtype_pl = (
            narwhals_to_native_dtype(dtype, version, backend_version) if dtype else None
        )
        # NOTE: `Iterable` is fine, annotation is overly narrow
        # https://github.com/pola-rs/polars/blob/82d57a4ee41f87c11ca1b1af15488459727efdd7/py-polars/polars/series/series.py#L332-L333
        native = pl.Series(name=name, values=cast("Sequence[Any]", data), dtype=dtype_pl)
        return cls.from_native(native, context=context)

    @staticmethod
    def _is_native(obj: pl.Series | Any) -> TypeIs[pl.Series]:
        return isinstance(obj, pl.Series)

    @classmethod
    def from_native(cls, data: pl.Series, /, *, context: _FullContext) -> Self:
        return cls(
            data, backend_version=context._backend_version, version=context._version
        )

    @classmethod
    def from_numpy(cls, data: Into1DArray, /, *, context: _FullContext) -> Self:
        native = pl.Series(data if is_numpy_array_1d(data) else [data])
        return cls.from_native(native, context=context)

    def _with_native(self, series: pl.Series) -> Self:
        return self.__class__(
            series, backend_version=self._backend_version, version=self._version
        )

    @overload
    def _from_native_object(self, series: pl.Series) -> Self: ...

    @overload
    def _from_native_object(self, series: pl.DataFrame) -> PolarsDataFrame: ...

    @overload
    def _from_native_object(self, series: T) -> T: ...

    def _from_native_object(
        self, series: pl.Series | pl.DataFrame | T
    ) -> Self | PolarsDataFrame | T:
        if self._is_native(series):
            return self._with_native(series)
        if isinstance(series, pl.DataFrame):
            from narwhals._polars.dataframe import PolarsDataFrame

            return PolarsDataFrame.from_native(series, context=self)
        # scalar
        return series

    def _to_expr(self) -> PolarsExpr:
        return self.__narwhals_namespace__()._expr._from_series(self)

    def __getattr__(self, attr: str) -> Any:
        if attr == "as_py":  # pragma: no cover
            raise AttributeError

        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._from_native_object(getattr(self.native, attr)(*pos, **kwds))

        return func

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

    @property
    def name(self) -> str:
        return self.native.name

    @property
    def dtype(self) -> DType:
        return native_to_narwhals_dtype(
            self.native.dtype, self._version, self._backend_version
        )

    @property
    def native(self) -> pl.Series:
        return self._native_series

    def alias(self, name: str) -> Self:
        return self._from_native_object(self.native.alias(name))

    def __getitem__(self, item: MultiIndexSelector[Self]) -> Any | Self:
        if isinstance(item, PolarsSeries):
            return self._from_native_object(self.native.__getitem__(item.native))
        return self._from_native_object(self.native.__getitem__(item))

    def cast(self, dtype: DType | type[DType]) -> Self:
        dtype_pl = narwhals_to_native_dtype(dtype, self._version, self._backend_version)
        return self._with_native(self.native.cast(dtype_pl))

    @requires.backend_version((1,))
    def replace_strict(
        self,
        old: Sequence[Any] | Mapping[Any, Any],
        new: Sequence[Any],
        *,
        return_dtype: DType | type[DType] | None,
    ) -> Self:
        ser = self.native
        dtype = (
            narwhals_to_native_dtype(return_dtype, self._version, self._backend_version)
            if return_dtype
            else None
        )
        return self._with_native(ser.replace_strict(old, new, return_dtype=dtype))

    def to_numpy(self, dtype: Any = None, *, copy: bool | None = None) -> _1DArray:
        return self.__array__(dtype, copy=copy)

    def __array__(self, dtype: Any, *, copy: bool | None) -> _1DArray:
        if self._backend_version < (0, 20, 29):
            return self.native.__array__(dtype=dtype)
        return self.native.__array__(dtype=dtype, copy=copy)

    def __eq__(self, other: object) -> Self:  # type: ignore[override]
        return self._with_native(self.native.__eq__(extract_native(other)))

    def __ne__(self, other: object) -> Self:  # type: ignore[override]
        return self._with_native(self.native.__ne__(extract_native(other)))

    def __ge__(self, other: Any) -> Self:
        return self._with_native(self.native.__ge__(extract_native(other)))

    def __gt__(self, other: Any) -> Self:
        return self._with_native(self.native.__gt__(extract_native(other)))

    def __le__(self, other: Any) -> Self:
        return self._with_native(self.native.__le__(extract_native(other)))

    def __lt__(self, other: Any) -> Self:
        return self._with_native(self.native.__lt__(extract_native(other)))

    def __and__(self, other: PolarsSeries | bool | Any) -> Self:
        return self._with_native(self.native.__and__(extract_native(other)))

    def __or__(self, other: PolarsSeries | bool | Any) -> Self:
        return self._with_native(self.native.__or__(extract_native(other)))

    def __add__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__add__(extract_native(other)))

    def __radd__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__radd__(extract_native(other)))

    def __sub__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__sub__(extract_native(other)))

    def __rsub__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__rsub__(extract_native(other)))

    def __mul__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__mul__(extract_native(other)))

    def __rmul__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__rmul__(extract_native(other)))

    def __pow__(self, other: PolarsSeries | Any) -> Self:
        return self._with_native(self.native.__pow__(extract_native(other)))

    def __rpow__(self, other: PolarsSeries | Any) -> Self:
        result = self.native.__rpow__(extract_native(other))
        if self._backend_version < (1, 16, 1):
            # Explicitly set alias to work around https://github.com/pola-rs/polars/issues/20071
            result = result.alias(self.name)
        return self._with_native(result)

    def __invert__(self) -> Self:
        return self._with_native(self.native.__invert__())

    def is_nan(self) -> Self:
        try:
            native_is_nan = self.native.is_nan()
        except Exception as e:  # noqa: BLE001
            raise catch_polars_exception(e, self._backend_version) from None
        if self._backend_version < (1, 18):  # pragma: no cover
            select = pl.when(self.native.is_not_null()).then(native_is_nan)
            return self._with_native(pl.select(select)[self.name])
        return self._with_native(native_is_nan)

    def median(self) -> Any:
        from narwhals.exceptions import InvalidOperationError

        if not self.dtype.is_numeric():
            msg = "`median` operation not supported for non-numeric input type."
            raise InvalidOperationError(msg)

        return self.native.median()

    def to_dummies(self, *, separator: str, drop_first: bool) -> PolarsDataFrame:
        from narwhals._polars.dataframe import PolarsDataFrame

        if self._backend_version < (0, 20, 15):
            has_nulls = self.native.is_null().any()
            result = self.native.to_dummies(separator=separator)
            output_columns = result.columns
            if drop_first:
                _ = output_columns.pop(int(has_nulls))

            result = result.select(output_columns)
        else:
            result = self.native.to_dummies(separator=separator, drop_first=drop_first)
        result = result.with_columns(pl.all().cast(pl.Int8))
        return PolarsDataFrame.from_native(result, context=self)

    def ewm_mean(
        self,
        *,
        com: float | None,
        span: float | None,
        half_life: float | None,
        alpha: float | None,
        adjust: bool,
        min_samples: int,
        ignore_nulls: bool,
    ) -> Self:
        extra_kwargs = (
            {"min_periods": min_samples}
            if self._backend_version < (1, 21, 0)
            else {"min_samples": min_samples}
        )

        native_result = self.native.ewm_mean(
            com=com,
            span=span,
            half_life=half_life,
            alpha=alpha,
            adjust=adjust,
            ignore_nulls=ignore_nulls,
            **extra_kwargs,
        )
        if self._backend_version < (1,):  # pragma: no cover
            return self._with_native(
                pl.select(
                    pl.when(~self.native.is_null()).then(native_result).otherwise(None)
                )[self.native.name]
            )

        return self._with_native(native_result)

    @requires.backend_version((1,))
    def rolling_var(
        self,
        window_size: int,
        *,
        min_samples: int,
        center: bool,
        ddof: int,
    ) -> Self:
        extra_kwargs: dict[str, Any] = (
            {"min_periods": min_samples}
            if self._backend_version < (1, 21, 0)
            else {"min_samples": min_samples}
        )
        return self._with_native(
            self.native.rolling_var(
                window_size=window_size, center=center, ddof=ddof, **extra_kwargs
            )
        )

    @requires.backend_version((1,))
    def rolling_std(
        self,
        window_size: int,
        *,
        min_samples: int,
        center: bool,
        ddof: int,
    ) -> Self:
        extra_kwargs: dict[str, Any] = (
            {"min_periods": min_samples}
            if self._backend_version < (1, 21, 0)
            else {"min_samples": min_samples}
        )
        return self._with_native(
            self.native.rolling_std(
                window_size=window_size, center=center, ddof=ddof, **extra_kwargs
            )
        )

    def rolling_sum(
        self,
        window_size: int,
        *,
        min_samples: int,
        center: bool,
    ) -> Self:
        extra_kwargs: dict[str, Any] = (
            {"min_periods": min_samples}
            if self._backend_version < (1, 21, 0)
            else {"min_samples": min_samples}
        )
        return self._with_native(
            self.native.rolling_sum(
                window_size=window_size, center=center, **extra_kwargs
            )
        )

    def rolling_mean(
        self,
        window_size: int,
        *,
        min_samples: int,
        center: bool,
    ) -> Self:
        extra_kwargs: dict[str, Any] = (
            {"min_periods": min_samples}
            if self._backend_version < (1, 21, 0)
            else {"min_samples": min_samples}
        )
        return self._with_native(
            self.native.rolling_mean(
                window_size=window_size, center=center, **extra_kwargs
            )
        )

    def sort(self, *, descending: bool, nulls_last: bool) -> Self:
        if self._backend_version < (0, 20, 6):
            result = self.native.sort(descending=descending)

            if nulls_last:
                is_null = result.is_null()
                result = pl.concat([result.filter(~is_null), result.filter(is_null)])
        else:
            result = self.native.sort(descending=descending, nulls_last=nulls_last)

        return self._with_native(result)

    def scatter(self, indices: int | Sequence[int], values: Any) -> Self:
        s = self.native.clone().scatter(indices, extract_native(values))
        return self._with_native(s)

    def value_counts(
        self,
        *,
        sort: bool,
        parallel: bool,
        name: str | None,
        normalize: bool,
    ) -> PolarsDataFrame:
        from narwhals._polars.dataframe import PolarsDataFrame

        if self._backend_version < (1, 0, 0):
            value_name_ = name or ("proportion" if normalize else "count")

            result = self.native.value_counts(sort=sort, parallel=parallel).select(
                **{
                    (self.native.name): pl.col(self.native.name),
                    value_name_: pl.col("count") / pl.sum("count")
                    if normalize
                    else pl.col("count"),
                }
            )
        else:
            result = self.native.value_counts(
                sort=sort, parallel=parallel, name=name, normalize=normalize
            )
        return PolarsDataFrame.from_native(result, context=self)

    def cum_count(self, *, reverse: bool) -> Self:
        if self._backend_version < (0, 20, 4):
            not_null_series = ~self.native.is_null()
            result = not_null_series.cum_sum(reverse=reverse)
        else:
            result = self.native.cum_count(reverse=reverse)

        return self._with_native(result)

    def __contains__(self, other: Any) -> bool:
        try:
            return self.native.__contains__(other)
        except Exception as e:  # noqa: BLE001
            raise catch_polars_exception(e, self._backend_version) from None

    def hist(
        self,
        bins: list[float | int] | None,
        *,
        bin_count: int | None,
        include_breakpoint: bool,
    ) -> PolarsDataFrame:
        from narwhals._polars.dataframe import PolarsDataFrame

        if (bins is not None and len(bins) <= 1) or (bin_count == 0):  # pragma: no cover
            data: list[pl.Series] = []
            if include_breakpoint:
                data.append(pl.Series("breakpoint", [], dtype=pl.Float64))
            data.append(pl.Series("count", [], dtype=pl.UInt32))
            return PolarsDataFrame.from_native(pl.DataFrame(data), context=self)

        if self.native.count() < 1:
            data_dict: dict[str, Sequence[Any] | pl.Series]
            if bins is not None:
                data_dict = {
                    "breakpoint": bins[1:],
                    "count": pl.zeros(n=len(bins) - 1, dtype=pl.Int64, eager=True),
                }
            elif (bin_count is not None) and bin_count == 1:
                data_dict = {"breakpoint": [1.0], "count": [0]}
            elif (bin_count is not None) and bin_count > 1:
                data_dict = {
                    "breakpoint": pl.int_range(1, bin_count + 1, eager=True) / bin_count,
                    "count": pl.zeros(n=bin_count, dtype=pl.Int64, eager=True),
                }
            else:  # pragma: no cover
                msg = (
                    "congratulations, you entered unreachable code - please report a bug"
                )
                raise AssertionError(msg)
            if not include_breakpoint:
                del data_dict["breakpoint"]
            return PolarsDataFrame.from_native(pl.DataFrame(data_dict), context=self)

        # polars <1.15 does not adjust the bins when they have equivalent min/max
        # polars <1.5 with bin_count=...
        # returns bins that range from -inf to +inf and has bin_count + 1 bins.
        #   for compat: convert `bin_count=` call to `bins=`
        if (self._backend_version < (1, 15)) and (
            bin_count is not None
        ):  # pragma: no cover
            lower = cast("float", self.native.min())
            upper = cast("float", self.native.max())
            if lower == upper:
                width = 1 / bin_count
                lower -= 0.5
                upper += 0.5
            else:
                width = (upper - lower) / bin_count

            bins = (pl.int_range(0, bin_count + 1, eager=True) * width + lower).to_list()
            bin_count = None

        # Polars inconsistently handles NaN values when computing histograms
        #   against predefined bins: https://github.com/pola-rs/polars/issues/21082
        series = self.native
        if self._backend_version < (1, 15) or bins is not None:
            series = series.set(series.is_nan(), None)

        df = series.hist(
            bins,
            bin_count=bin_count,
            include_category=False,
            include_breakpoint=include_breakpoint,
        )

        if not include_breakpoint:
            df.columns = ["count"]

        if self._backend_version < (1, 0) and include_breakpoint:
            df = df.rename({"break_point": "breakpoint"})

        #  polars<1.15 implicitly adds -inf and inf to either end of bins
        if self._backend_version < (1, 15) and bins is not None:  # pragma: no cover
            r = pl.int_range(0, len(df))
            df = df.filter((r > 0) & (r < len(df) - 1))

        # polars<1.27 makes the lowest bin a left/right closed interval.
        if self._backend_version < (1, 27) and bins is not None:
            df[0, "count"] += (series == bins[0]).sum()

        return PolarsDataFrame.from_native(df, context=self)

    def to_polars(self) -> pl.Series:
        return self.native

    @property
    def dt(self) -> PolarsSeriesDateTimeNamespace:
        return PolarsSeriesDateTimeNamespace(self)

    @property
    def str(self) -> PolarsSeriesStringNamespace:
        return PolarsSeriesStringNamespace(self)

    @property
    def cat(self) -> PolarsSeriesCatNamespace:
        return PolarsSeriesCatNamespace(self)

    @property
    def struct(self) -> PolarsSeriesStructNamespace:
        return PolarsSeriesStructNamespace(self)

    __iter__: Method[Iterator[Any]]
    __floordiv__: Method[Self]
    __mod__: Method[Self]
    __rand__: Method[Self]
    __rfloordiv__: Method[Self]
    __rmod__: Method[Self]
    __ror__: Method[Self]
    __rtruediv__: Method[Self]
    __truediv__: Method[Self]
    abs: Method[Self]
    all: Method[bool]
    any: Method[bool]
    arg_max: Method[int]
    arg_min: Method[int]
    arg_true: Method[Self]
    clip: Method[Self]
    count: Method[int]
    cum_max: Method[Self]
    cum_min: Method[Self]
    cum_prod: Method[Self]
    cum_sum: Method[Self]
    diff: Method[Self]
    drop_nulls: Method[Self]
    fill_null: Method[Self]
    filter: Method[Self]
    gather_every: Method[Self]
    head: Method[Self]
    is_between: Method[Self]
    is_finite: Method[Self]
    is_first_distinct: Method[Self]
    is_in: Method[Self]
    is_last_distinct: Method[Self]
    is_null: Method[Self]
    is_sorted: Method[bool]
    is_unique: Method[Self]
    item: Method[Any]
    len: Method[int]
    max: Method[Any]
    mean: Method[float]
    min: Method[Any]
    mode: Method[Self]
    n_unique: Method[int]
    null_count: Method[int]
    quantile: Method[float]
    rank: Method[Self]
    round: Method[Self]
    sample: Method[Self]
    shift: Method[Self]
    skew: Method[float | None]
    std: Method[float]
    sum: Method[float]
    tail: Method[Self]
    to_arrow: Method[ArrowArray]
    to_frame: Method[PolarsDataFrame]
    to_list: Method[list[Any]]
    to_pandas: Method[pd.Series[Any]]
    unique: Method[Self]
    var: Method[float]
    zip_with: Method[Self]

    @property
    def list(self) -> PolarsSeriesListNamespace:
        return PolarsSeriesListNamespace(self)


class PolarsSeriesDateTimeNamespace:
    def __init__(self, series: PolarsSeries) -> None:
        self._compliant_series = series

    def __getattr__(self, attr: str) -> Any:
        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._compliant_series._with_native(
                getattr(self._compliant_series.native.dt, attr)(*pos, **kwds)
            )

        return func


class PolarsSeriesStringNamespace:
    def __init__(self, series: PolarsSeries) -> None:
        self._compliant_series = series

    def __getattr__(self, attr: str) -> Any:
        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._compliant_series._with_native(
                getattr(self._compliant_series.native.str, attr)(*pos, **kwds)
            )

        return func


class PolarsSeriesCatNamespace:
    def __init__(self, series: PolarsSeries) -> None:
        self._compliant_series = series

    def __getattr__(self, attr: str) -> Any:
        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._compliant_series._with_native(
                getattr(self._compliant_series.native.cat, attr)(*pos, **kwds)
            )

        return func


class PolarsSeriesListNamespace:
    def __init__(self, series: PolarsSeries) -> None:
        self._series = series

    def len(self) -> PolarsSeries:
        native_series = self._series.native
        native_result = native_series.list.len()

        if self._series._backend_version < (1, 16):  # pragma: no cover
            native_result = pl.select(
                pl.when(~native_series.is_null()).then(native_result).otherwise(None)
            )[native_series.name].cast(pl.UInt32())

        elif self._series._backend_version < (1, 17):  # pragma: no cover
            native_result = native_series.cast(pl.UInt32())

        return self._series._with_native(native_result)

    # TODO(FBruzzesi): Remove `pragma: no cover` once other namespace methods are added
    def __getattr__(self, attr: str) -> Any:  # pragma: no cover
        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._series._with_native(
                getattr(self._series.native.list, attr)(*pos, **kwds)
            )

        return func


class PolarsSeriesStructNamespace:
    def __init__(self, series: PolarsSeries) -> None:
        self._compliant_series = series

    def __getattr__(self, attr: str) -> Any:
        def func(*args: Any, **kwargs: Any) -> Any:
            pos, kwds = extract_args_kwargs(args, kwargs)
            return self._compliant_series._with_native(
                getattr(self._compliant_series.native.struct, attr)(*pos, **kwds)
            )

        return func