"""Server configuration, read from environment variables."""

from __future__ import annotations

import os
from dataclasses import dataclass


def _float(name: str, default: float) -> float:
    return float(os.environ.get(name, default))


def _int(name: str, default: int) -> int:
    return int(os.environ.get(name, default))


@dataclass(frozen=True)
class Settings:
    # Shared secret the AI service has to present on /internal/ai.
    # Empty disables authentication (development only).
    ai_shared_secret: str = os.environ.get("AI_SHARED_SECRET", "")
    # Seconds to wait for the AI service before falling back to a random move.
    ai_decision_timeout: float = _float("AI_DECISION_TIMEOUT", 5.0)
    # Minimum "thinking" time of AI players so humans can follow the game.
    ai_move_delay: float = _float("AI_MOVE_DELAY", 0.8)
    # Pause after a completed trick before AI players continue.
    trick_pause: float = _float("TRICK_PAUSE", 1.8)
    # Sessions without a connection are dropped after this many seconds.
    session_ttl: float = _float("SESSION_TTL", 1800.0)
    # Maximum number of simultaneously existing lobbies.
    max_lobbies: int = _int("MAX_LOBBIES", 1000)
    # Comma separated list of allowed websocket origins; empty allows all.
    allowed_origins: tuple[str, ...] = tuple(
        origin.strip() for origin in os.environ.get("ALLOWED_ORIGINS", "").split(",") if origin.strip()
    )
    log_level: str = os.environ.get("LOG_LEVEL", "INFO")

    # --- Abuse limits -------------------------------------------------------
    # Open websocket connections in total and per client IP.
    max_connections: int = _int("MAX_CONNECTIONS", 500)
    max_connections_per_ip: int = _int("MAX_CONNECTIONS_PER_IP", 10)
    # Messages per second a single connection may send (token bucket).
    message_rate: float = _float("MESSAGE_RATE", 10.0)
    message_burst: int = _int("MESSAGE_BURST", 30)
    # Dropped messages after which a flooding connection is closed.
    max_rate_violations: int = _int("MAX_RATE_VIOLATIONS", 50)
    # Lobbies a single IP may create per minute.
    lobby_create_rate: int = _int("LOBBY_CREATE_RATE", 10)

    # --- Load control -------------------------------------------------------
    # Games running at the same time; further game starts are refused.
    max_active_games: int = _int("MAX_ACTIVE_GAMES", 50)
    load_sample_interval: float = _float("LOAD_SAMPLE_INTERVAL", 1.0)
    # Event loop lag (seconds) / CPU share of the available quota (0..1).
    load_lag_busy: float = _float("LOAD_LAG_BUSY", 0.1)
    load_lag_overload: float = _float("LOAD_LAG_OVERLOAD", 0.25)
    # A single sample with this much lag means overload right away: when the
    # server is that slow, even the load sampler runs rarely.
    load_lag_severe: float = _float("LOAD_LAG_SEVERE", 1.0)
    load_cpu_busy: float = _float("LOAD_CPU_BUSY", 0.7)
    load_cpu_overload: float = _float("LOAD_CPU_OVERLOAD", 0.9)
    # Share of CPU periods in which the container was throttled (cgroup v2).
    load_throttle_overload: float = _float("LOAD_THROTTLE_OVERLOAD", 0.5)
    # Consecutive overloaded samples to enter / good samples to leave overload.
    load_overload_samples: int = _int("LOAD_OVERLOAD_SAMPLES", 3)
    load_recover_samples: int = _int("LOAD_RECOVER_SAMPLES", 10)
    # "normal", "busy" or "overloaded" to pin the level (testing only).
    load_force_level: str = os.environ.get("LOAD_FORCE_LEVEL", "")

    # --- AI service protection ----------------------------------------------
    # Unanswered decide requests per AI connection before falling back.
    # Each running game has at most one AI deciding at a time, so keep this at
    # least MAX_ACTIVE_GAMES; 64 matches the AI service's AI_MAX_QUEUE.
    ai_max_inflight: int = _int("AI_MAX_INFLIGHT", 64)
    # Consecutive AI failures that pause AI requests for ai_breaker_cooldown seconds.
    ai_breaker_failures: int = _int("AI_BREAKER_FAILURES", 5)
    ai_breaker_cooldown: float = _float("AI_BREAKER_COOLDOWN", 30.0)


settings = Settings()