"""Map signal values to discrete position actions."""
from dataclasses import dataclass


@dataclass
class PositionAction:
    """A target action for a single stock on a single bar."""

    action: str  # "buy", "sell", or "hold"
    size_pct: float = 0.0  # target portfolio fraction for buys


class ThresholdBuilder:
    """Open on strong positive signal, close on strong negative signal."""

    def __init__(
        self,
        buy_threshold: float = 0.02,
        sell_threshold: float = -0.02,
        size_pct: float = 0.95,
    ):
        self.buy_threshold = buy_threshold
        self.sell_threshold = sell_threshold
        self.size_pct = size_pct

    def build(self, signal_value: float, in_position: bool) -> PositionAction:
        """Decide what to do given the current signal and position state.

        Args:
            signal_value: Latest signal value for the stock.
            in_position: Whether the portfolio currently holds the stock.

        Returns:
            The action to take ("buy", "sell", or "hold").
        """
        if not in_position and signal_value >= self.buy_threshold:
            return PositionAction("buy", self.size_pct)
        if in_position and signal_value <= self.sell_threshold:
            return PositionAction("sell", 0.0)
        return PositionAction("hold", 0.0)