# Copyright 2023 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

import datetime as dt
from typing import Optional

import bigframes_vendored.pandas.core.arrays.datetimelike as vendored_pandas_datetimelike
import bigframes_vendored.pandas.core.indexes.accessor as vendordt
import pandas

from bigframes import dataframe, dtypes, series
from bigframes.core import log_adapter
import bigframes.operations as ops

_ONE_DAY = pandas.Timedelta("1d")
_ONE_SECOND = pandas.Timedelta("1s")
_ONE_MICRO = pandas.Timedelta("1us")
_SUPPORTED_FREQS = ("Y", "Q", "M", "W", "D", "h", "min", "s", "ms", "us")


@log_adapter.class_logger
class DatetimeMethods(
    vendordt.DatetimeProperties,
    vendored_pandas_datetimelike.DatelikeOps,
):
    __doc__ = vendordt.DatetimeProperties.__doc__

    def __init__(self, data: series.Series):
        self._data = data

    # Date accessors
    @property
    def day(self) -> series.Series:
        return self._data._apply_unary_op(ops.day_op)

    @property
    def dayofweek(self) -> series.Series:
        return self._data._apply_unary_op(ops.dayofweek_op)

    @property
    def day_of_week(self) -> series.Series:
        return self.dayofweek

    @property
    def dayofyear(self) -> series.Series:
        return self._data._apply_unary_op(ops.dayofyear_op)

    @property
    def day_of_year(self) -> series.Series:
        return self.dayofyear

    @property
    def date(self) -> series.Series:
        return self._data._apply_unary_op(ops.date_op)

    @property
    def quarter(self) -> series.Series:
        return self._data._apply_unary_op(ops.quarter_op)

    @property
    def year(self) -> series.Series:
        return self._data._apply_unary_op(ops.year_op)

    @property
    def month(self) -> series.Series:
        return self._data._apply_unary_op(ops.month_op)

    def isocalendar(self) -> dataframe.DataFrame:
        iso_ops = [ops.iso_year_op, ops.iso_week_op, ops.iso_day_op]
        labels = pandas.Index(["year", "week", "day"])
        block = self._data._block.project_exprs(
            [op.as_expr(self._data._value_column) for op in iso_ops], labels, drop=True
        )
        return dataframe.DataFrame(block)

    # Time accessors
    @property
    def hour(self) -> series.Series:
        return self._data._apply_unary_op(ops.hour_op)

    @property
    def minute(self) -> series.Series:
        return self._data._apply_unary_op(ops.minute_op)

    @property
    def second(self) -> series.Series:
        return self._data._apply_unary_op(ops.second_op)

    @property
    def time(self) -> series.Series:
        return self._data._apply_unary_op(ops.time_op)

    # Timedelta accessors
    @property
    def days(self) -> series.Series:
        self._check_dtype(dtypes.TIMEDELTA_DTYPE)

        return self._data._apply_binary_op(_ONE_DAY, ops.floordiv_op)

    @property
    def seconds(self) -> series.Series:
        self._check_dtype(dtypes.TIMEDELTA_DTYPE)

        return self._data._apply_binary_op(_ONE_DAY, ops.mod_op) // _ONE_SECOND  # type: ignore

    @property
    def microseconds(self) -> series.Series:
        self._check_dtype(dtypes.TIMEDELTA_DTYPE)

        return self._data._apply_binary_op(_ONE_SECOND, ops.mod_op) // _ONE_MICRO  # type: ignore

    def total_seconds(self) -> series.Series:
        self._check_dtype(dtypes.TIMEDELTA_DTYPE)

        return self._data._apply_binary_op(_ONE_SECOND, ops.div_op)

    def _check_dtype(self, target_dtype: dtypes.Dtype):
        if self._data._dtype == target_dtype:
            return
        raise TypeError(f"Expect dtype: {target_dtype}, but got {self._data._dtype}")

    @property
    def tz(self) -> Optional[dt.timezone]:
        # Assumption: pyarrow dtype
        tz_string = self._data._dtype.pyarrow_dtype.tz
        if tz_string == "UTC":
            return dt.timezone.utc
        elif tz_string is None:
            return None
        else:
            raise ValueError(f"Unexpected timezone {tz_string}")

    @property
    def unit(self) -> str:
        # Assumption: pyarrow dtype
        return self._data._dtype.pyarrow_dtype.unit

    def day_name(self) -> series.Series:
        return self.strftime("%A")

    def strftime(self, date_format: str) -> series.Series:
        return self._data._apply_unary_op(ops.StrftimeOp(date_format=date_format))

    def normalize(self) -> series.Series:
        return self._data._apply_unary_op(ops.normalize_op)

    def floor(self, freq: str) -> series.Series:
        if freq not in _SUPPORTED_FREQS:
            raise ValueError(f"freq must be one of {_SUPPORTED_FREQS}")
        return self._data._apply_unary_op(ops.FloorDtOp(freq=freq))  # type: ignore
