"""选股策略 Repository 的 SQLAlchemy 实现。

config_json 只存选股相关字段（universe/factors/conditions）；读取时重建 SelectionStrategy。
2026-09 重构：策略库不再持有回测执行参数（selection/rebalance/costs/portfolio/区间），
旧行若残留这些键，读出时由 Pydantic 的 extra 忽略策略丢弃（见 _to_entity）。
"""

from __future__ import annotations

import json
from datetime import datetime

from sqlalchemy import select
from sqlalchemy.orm import Session

from app.domain.entities.strategy import SelectionStrategy
from app.infrastructure.persistence.sqlalchemy.models.strategy import StrategyModel


class SqlAlchemyStrategyRepository:
    def __init__(self, session: Session) -> None:
        self._session = session

    def save(self, definition: SelectionStrategy) -> SelectionStrategy:
        if not definition.id:
            raise ValueError("需要 id（由调用方生成）")
        dup = self._session.scalar(
            select(StrategyModel).where(StrategyModel.name == definition.name).limit(1)
        )
        if dup is not None and dup.id != definition.id:
            raise ValueError(f"策略名已存在：{definition.name}")
        now = definition.created_at or datetime.now()
        row = self._session.get(StrategyModel, definition.id)
        config_json = json.dumps(definition.model_dump(exclude={"id", "created_at"}), ensure_ascii=False)
        if row is None:
            self._session.add(
                StrategyModel(
                    id=definition.id,
                    name=definition.name,
                    description=definition.description,
                    spec_type=definition.spec_type,
                    config_json=config_json,
                    version=definition.version,
                    created_at=now,
                )
            )
        else:
            row.name = definition.name
            row.description = definition.description
            row.spec_type = definition.spec_type
            row.config_json = config_json
            row.version = definition.version
        self._session.flush()
        return definition

    def get(self, strategy_id: str) -> SelectionStrategy | None:
        row = self._session.get(StrategyModel, strategy_id)
        return _to_entity(row) if row else None

    def get_by_name(self, name: str) -> SelectionStrategy | None:
        row = self._session.scalar(
            select(StrategyModel).where(StrategyModel.name == name).limit(1)
        )
        return _to_entity(row) if row else None

    def list(self) -> list[SelectionStrategy]:
        rows = self._session.scalars(
            select(StrategyModel).order_by(StrategyModel.name)
        ).all()
        return [_to_entity(r) for r in rows]

    def delete(self, strategy_id: str) -> bool:
        row = self._session.get(StrategyModel, strategy_id)
        if row is None:
            return False
        self._session.delete(row)
        return True


# 旧 strategy.config_json 可能残留的回测执行参数字段（重构前写入）—— 读出时丢弃，
# 因为 SelectionStrategy 不再承载它们（已迁到回测组合 / 公共配置）。
_LEGACY_BACKTEST_KEYS = frozenset({
    "selection", "rebalance", "costs", "portfolio", "price_adjustment",
    "selection_interval_months", "rebalance_interval_months",
})


def _to_entity(row: StrategyModel) -> SelectionStrategy:
    data = json.loads(row.config_json)
    # 列字段由 DB 行回填，避免与 config_json 重复。
    # description 必须一并回填：它是列字段（String(300)），save() 会写入，
    # 但这里若只从 config_json 里 pop 掉却不回填，读回的策略说明会恒为空串
    # （读写不对称：保存的说明看不到，策略库/编辑页都拿不到）。
    for key in ("name", "version", "description", "spec_type"):
        data.pop(key, None)
    # 丢弃旧行的回测参数字段（Pydantic 默认 forbid extra 会因这些键报错）
    for key in _LEGACY_BACKTEST_KEYS:
        data.pop(key, None)
    return SelectionStrategy(
        id=row.id, name=row.name, version=row.version, description=row.description,
        created_at=row.created_at, **data,
    )