"""ICMP / TCP reachability checks — pure probes returning a result dict."""
from __future__ import annotations
import asyncio
import logging
import time

logger = logging.getLogger(__name__)

TCP_TIMEOUT = 5.0
DEFAULT_TCP_PORT = 80


async def tcp_check(address: str, port: int) -> dict:
    """TCP connect probe. Returns {is_up, response_ms}."""
    start = time.monotonic()
    try:
        reader, writer = await asyncio.wait_for(
            asyncio.open_connection(address, port),
            timeout=TCP_TIMEOUT,
        )
        writer.close()
        await writer.wait_closed()
        return {"is_up": True, "response_ms": round((time.monotonic() - start) * 1000, 2)}
    except Exception:
        return {"is_up": False, "response_ms": None}


async def icmp_check(address: str) -> dict:
    """ICMP echo via the system ping binary (setuid; no raw-socket privilege).

    Falls back to a TCP connect on the default port if the ping binary is
    unavailable or errors, so a host with ICMP filtered still gets a signal.
    """
    start = time.monotonic()
    try:
        proc = await asyncio.create_subprocess_exec(
            "ping", "-c", "1", "-W", "2", address,
            stdout=asyncio.subprocess.DEVNULL,
            stderr=asyncio.subprocess.DEVNULL,
        )
        await asyncio.wait_for(proc.wait(), timeout=5.0)
        if proc.returncode == 0:
            return {"is_up": True, "response_ms": round((time.monotonic() - start) * 1000, 2)}
        return {"is_up": False, "response_ms": None}
    except Exception as exc:
        logger.warning("ICMP ping failed for %s: %s, falling back to TCP", address, exc)
        return await tcp_check(address, DEFAULT_TCP_PORT)