from __future__ import annotations
from typing import List
from .dsl import PlanDelta, StrategyDelta


class Backtester:
    """Toy deterministic replay engine for end-to-end validation."""

    def __init__(self, seed: int = 0):
        self.seed = seed

    def replay(self, plan: PlanDelta) -> float:
        # Very naive replay: sum absolute deltas to produce a pseudo-PnL
        pnl = sum(abs(a.delta) for a in plan.actions)
        # Incorporate timestamp entropy for determinism in tests
        pnl += (plan.timestamp or 0.0) * 1e-6
        return float(pnl)