from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any, Dict, List
import time


@dataclass
class RuntimeMetrics:
    events: List[Dict[str, Any]] = field(default_factory=list)
    started_at: float = field(default_factory=time.perf_counter)

    def record(self, event: str, **values: Any) -> None:
        self.events.append({"event": event, "timestamp": time.time(), **values})

    def snapshot(self) -> Dict[str, Any]:
        durations = {
            event["event"]: event.get("duration_ms")
            for event in self.events
            if event.get("duration_ms") is not None
        }
        return {
            "events": list(self.events),
            "event_count": len(self.events),
            "active_runtime_slots": sum(1 for event in self.events if event["event"] == "runtime.created") - sum(1 for event in self.events if event["event"] == "runtime.destroyed"),
            "durations_ms": durations,
            "elapsed_ms": round((time.perf_counter() - self.started_at) * 1000, 3),
        }