from __future__ import annotations

import os
import platform
from dataclasses import dataclass


def detect_os_type() -> str:
    system_name = platform.system().upper()
    if system_name.startswith("WIN"):
        return "WINDOWS"
    if system_name.startswith("LINUX"):
        return "LINUX"
    return system_name or "UNKNOWN"


@dataclass(slots=True)
class Settings:
    backend_base_url: str
    edge_id: str
    edge_name: str
    edge_hostname: str
    edge_os_type: str
    edge_agent_version: str
    edge_access_token: str | None
    poll_interval_ms: int
    heartbeat_interval_ms: int
    request_timeout_ms: int
    default_health_check_timeout_ms: int


def get_settings() -> Settings:
    return Settings(
        backend_base_url=os.getenv("BACKEND_BASE_URL", "http://127.0.0.1:8000").rstrip("/"),
        edge_id=os.getenv("EDGE_ID", "edge-shanghai-001"),
        edge_name=os.getenv("EDGE_NAME", "edge-agent-demo"),
        edge_hostname=os.getenv("EDGE_HOSTNAME", platform.node() or "localhost"),
        edge_os_type=os.getenv("EDGE_OS_TYPE", detect_os_type()),
        edge_agent_version=os.getenv("EDGE_AGENT_VERSION", "0.1.0"),
        edge_access_token=os.getenv("EDGE_ACCESS_TOKEN"),
        poll_interval_ms=int(os.getenv("POLL_INTERVAL_MS", "3000")),
        heartbeat_interval_ms=int(os.getenv("HEARTBEAT_INTERVAL_MS", "10000")),
        request_timeout_ms=int(os.getenv("REQUEST_TIMEOUT_MS", "5000")),
        default_health_check_timeout_ms=int(os.getenv("DEFAULT_HEALTH_CHECK_TIMEOUT_MS", "3000")),
    )