from __future__ import annotations

import json
from dataclasses import dataclass
from pathlib import Path
from typing import Literal

Strategy = Literal["broadcast", "top2", "top3", "top4", "backup"]


@dataclass
class RelayNode:
    name: str
    host: str
    port: int
    token: str
    weight: int = 100


@dataclass
class Config:
    relays: list[RelayNode]
    strategy: Strategy = "top3"
    redundancy: int = 3
    tcp_warmup_bytes: int = 1048576
    probe_interval: float = 15.0
    tcp_loser_grace_ms: int = 1500

    @classmethod
    def load(cls, path: str) -> "Config":
        raw = json.loads(Path(path).read_text())
        relays = [RelayNode(**item) for item in raw["relays"]]
        return cls(
            relays=relays,
            strategy=raw.get("strategy", "top3"),
            redundancy=raw.get("redundancy", 3),
            tcp_warmup_bytes=raw.get("tcp_warmup_bytes", 1048576),
            probe_interval=raw.get("probe_interval", 15.0),
            tcp_loser_grace_ms=raw.get("tcp_loser_grace_ms", 1500),
        )