"""ZT 正T/反T 的触发与数量规则：纯函数，不碰网络、存储和线程。

设计要点：

* 以建仓价 ``base_cost`` 为中枢，中性带 ``zt_t_band_pct`` 内不做任何动作。
  现价低于下沿只考虑正T，高于上沿只考虑反T —— 同一时刻只可能命中一种方向，
  天然满足"一只股票每天只做一轮"，不需要额外的冲突仲裁。
* 数量一律再受券商现实约束封顶：卖出封顶 ``can_use_volume``（T+1 只在这里
  体现），买入封顶可用资金。正T 当天买入的份额当天不可卖，因此它的平仓腿
  能卖多少完全由 ``can_use_volume`` 决定，卖不动就自然留成隔夜持仓。
"""

from .rounds import KIND_LONG_T, KIND_SHORT_T

LOT = 100


def choose_kind(price: float, base_cost: float, band_pct: float) -> str | None:
    """按现价相对建仓价的位置决定本轮方向；中性带内返回 None。"""
    if price <= 0 or base_cost <= 0 or band_pct < 0:
        return None
    if price <= base_cost * (1 - band_pct / 100):
        return KIND_LONG_T
    if price >= base_cost * (1 + band_pct / 100):
        return KIND_SHORT_T
    return None


def price_allowed(price: float, max_price: float) -> bool:
    """高价股不参与做 T。"""
    return 0 < price <= max_price


def entry_volume(kind: str, *, price: float, open_hands: int, sell_ratio: float,
                 base_qty: int, can_use_volume: int, available: float) -> int:
    """开仓腿计划数量；0 表示不提交。"""
    if price <= 0:
        return 0
    if kind == KIND_LONG_T:
        # 正T 买入：按手数取量，再受可用资金封顶。
        affordable = int(max(0.0, available) // (price * LOT)) * LOT
        return max(0, min(open_hands * LOT, affordable))
    if kind == KIND_SHORT_T:
        # 反T 卖出：按建仓数量比例取整手，再受可卖库存封顶。
        planned = int(base_qty * sell_ratio) // LOT * LOT
        return max(0, min(planned, _whole_lots(can_use_volume)))
    return 0


def exit_volume(kind: str, *, residual_qty: int, price: float,
                can_use_volume: int, available: float) -> int:
    """平仓腿可提交数量；0 表示当前无法平仓（T+1 冻结或资金不足）。"""
    if residual_qty <= 0 or price <= 0:
        return 0
    if kind == KIND_LONG_T:
        return max(0, min(residual_qty, _whole_lots(can_use_volume)))
    if kind == KIND_SHORT_T:
        affordable = int(max(0.0, available) // (price * LOT)) * LOT
        return max(0, min(residual_qty, affordable))
    return 0


def entry_triggered(kind: str, price: float, base_cost: float, *, band_pct: float,
                    rebound_confirmed: bool, retrace_confirmed: bool) -> bool:
    """开仓腿是否满足触发条件。"""
    if choose_kind(price, base_cost, band_pct) != kind:
        return False
    if kind == KIND_LONG_T:
        return rebound_confirmed      # 低吸要等反弹确认，不接下跌中的飞刀
    return retrace_confirmed          # 高抛要等盈利网格回撤，不追最高点


def exit_triggered(kind: str, price: float, entry_avg_price: float, *,
                   buy_fall_pct: float, profit_step_pct: float,
                   rebound_confirmed: bool) -> bool:
    """平仓腿是否满足触发条件。"""
    if entry_avg_price <= 0:
        return False
    if kind == KIND_SHORT_T:
        # 反T 买回：较卖出均价回落 buy_fall_pct 且已见反弹。
        target = entry_avg_price * (1 - buy_fall_pct / 100)
        return price <= target and rebound_confirmed
    if kind == KIND_LONG_T:
        # 正T 卖出：较买入均价上涨一个网格步长。
        return price >= entry_avg_price * (1 + profit_step_pct / 100)
    return False


def _whole_lots(volume: int) -> int:
    return max(0, int(volume)) // LOT * LOT