"""
因子算子框架 - Polars 实现
支持：截面滚动 → 拼回长表 → 按列名合并
返回形式可选：完整 DataFrame（默认）或单列 Series
"""

from abc import ABC, abstractmethod
from dataclasses import dataclass
from typing import List, Literal

import polars as pl


@dataclass
class OperatorConfig:
    """算子配置"""
    name: str
    description: str
    required_columns: List[str]
    output_columns: List[str]
    parameters: dict


class BaseOperator(ABC):
    """算子基类"""

    def __init__(self, config: OperatorConfig):
        self.config = config
        self.name = config.name
        self.required_columns = config.required_columns
        self.output_columns = config.output_columns

    # ---------- 子类必须实现 ----------
    @abstractmethod
    def get_factor_name(self) -> str:
        """返回因子列名（用于合并）"""
        pass

    @abstractmethod
    def calc_factor(self, group_df: pl.DataFrame, **kwargs) -> pl.Series:
        """
        真正的截面计算逻辑。
        参数：按 ts_code 或 trade_date 分组后的子表
        返回：与 group_df 行数一一对应的因子 Series（含正确索引）
        """
        pass

    # ---------- 公共接口 ----------
    def apply(self,
              df: pl.DataFrame,
              return_type: Literal['df', 'series'] = 'df',
              **kwargs) -> pl.DataFrame | pl.Series:
        """入口：截面滚动 → 拼回长表 → 合并/返回"""
        if not self.validate_input(df):
            raise ValueError(f"缺少必需列：{self.required_columns}")

        long_table = self._sectional_roll(df, **kwargs)          # ① 滚动
        merged = self._merge_factor(df, long_table)              # ② 合并
        return merged if return_type == 'df' else merged[self.get_factor_name()]

    # ---------- 内部流程 ----------
    def validate_input(self, df: pl.DataFrame) -> bool:
        return all(col in df.columns for col in self.required_columns)

    @abstractmethod
    def _sectional_roll(self, df: pl.DataFrame, **kwargs) -> pl.DataFrame:
        """
        截面滚动模板：group → calc_factor → 拼回长表
        返回：含【trade_date, ts_code, factor】的长表
        """
        pass

    def _merge_factor(self, original: pl.DataFrame, factor_table: pl.DataFrame) -> pl.DataFrame:
        """按 [ts_code, trade_date] 左联，原地追加因子列"""
        factor_name = self.get_factor_name()
        return original.join(factor_table.select(['ts_code', 'trade_date', factor_name]),
                             on=['ts_code', 'trade_date'],
                             how='left')


# -------------------- 股票截面：按 ts_code 分组 --------------------
class StockWiseOperator(BaseOperator):
    """股票切面算子抽象类：按 ts_code 分组，对每个股票的时间序列计算因子"""

    def _sectional_roll(self, df: pl.DataFrame, **kwargs) -> pl.DataFrame:
        factor_name = self.get_factor_name()
        
        # 确保排序（时间顺序对 shift 等操作至关重要）
        df_sorted = df.sort(['ts_code', 'trade_date'])
        
        # 使用 map_groups：对每个 ts_code 分组，传入完整子 DataFrame
        result = (
            df_sorted
            .group_by('ts_code', maintain_order=True)
            .map_groups(
                lambda group_df: group_df.with_columns(
                    self.calc_factor(group_df, **kwargs)
                )
            )
            .select(['ts_code', 'trade_date', factor_name])
        )
        return result

# -------------------- 日期截面：按 trade_date 分组 --------------------
class DateWiseOperator(BaseOperator):
    """日期切面算子抽象类：按 trade_date 分组，对每个截面计算因子"""

    def _sectional_roll(self, df: pl.DataFrame, **kwargs) -> pl.DataFrame:
        factor_name = self.get_factor_name()
        
        df_sorted = df.sort(['trade_date', 'ts_code'])
        
        result = (
            df_sorted
            .group_by('trade_date', maintain_order=True)
            .map_groups(
                lambda group_df: group_df.with_columns(
                    self.calc_factor(group_df, **kwargs)
                )
            )
            .select(['ts_code', 'trade_date', factor_name])
        )
        return result