from __future__ import annotations
from typing import List, Optional, Dict, Any
from .dsl import LocalEvent, PlanDelta, OrderEvent, FillEvent, TraceGraph

class ReplayEngine:
  def __init__(self, delta_stream: List[object], event_log: List[object]):
    self.delta_stream = delta_stream
    self.event_log = event_log

  def replay(self) -> Dict[str, Any]:
    deltas_by_id = {}
    for item in self.delta_stream:
      if isinstance(item, PlanDelta):
        deltas_by_id[item.delta_id] = item

    known = 0
    total = 0
    details: List[str] = []
    for ev in self.event_log:
      if isinstance(ev, FillEvent):
        total += 1
        if ev.delta_id and ev.delta_id in deltas_by_id:
          known += 1
          details.append(f"Fill {ev.fill_id} matched delta {ev.delta_id}")
        else:
          details.append(f"Fill {ev.fill_id} has no matching delta")
    fidelity = (known / total) if total else 0.0
    return {
      "total_fills": total,
      "known_delta_fills": known,
      "fidelity": fidelity,
      "details": details,
    }