"""Periodic latency monitor for controls network devices."""
from __future__ import annotations

import os
import re
import signal
import subprocess
import sys
import time
from contextlib import contextmanager
from dataclasses import dataclass
from datetime import datetime, timezone
from typing import Iterable, Optional

import mysql.connector

PING_TIMEOUT_MS = int(os.environ.get("LATENCY_PING_TIMEOUT_MS", "2000"))
POLL_INTERVAL_SECONDS = int(os.environ.get("LATENCY_POLL_INTERVAL", "15"))
DB_CONFIG = {
    "host": os.environ.get("CONTROLS_DB_HOST", "localhost"),
    "user": os.environ.get("CONTROLS_DB_USER", "corey"),
    "password": os.environ.get("CONTROLS_DB_PASSWORD", "41945549"),
    "database": os.environ.get("CONTROLS_DB_NAME", "controls"),
    "port": int(os.environ.get("CONTROLS_DB_PORT", "3306")),
    "autocommit": False,
    "connection_timeout": 5,  # Add this line
}

STATUS_UP = "up"
STATUS_DOWN = "down"
STATUS_UNKNOWN = "unknown"


@dataclass
class Device:
    device_id: int
    host: str
    label: str


@dataclass
class PingResult:
    device: Device
    status: str
    latency_ms: Optional[int]
    checked_at: datetime


@contextmanager
def mysql_connection():
    print("About to connect to MySQL...")  # Debug
    try:
        connection = mysql.connector.connect(**DB_CONFIG)
        print("Connected to MySQL!")  # Debug
        yield connection
    except Exception as e:
        print(f"Error connecting to MySQL: {e}", file=sys.stderr)
        raise
    finally:
        try:
            connection.close()
        except Exception:
            pass


def fetch_devices(connection) -> Iterable[Device]:
    cursor = connection.cursor(dictionary=True)
    cursor.execute(
        "SELECT id, host, label FROM monitoring_devices WHERE is_active = 1 ORDER BY id"
    )
    for row in cursor:
        yield Device(device_id=row["id"], host=row["host"], label=row["label"])
    cursor.close()


def ping_device(host: str) -> tuple[str, Optional[int]]:
    command = [
        "ping",
        "-n",
        "1",
        "-w",
        str(PING_TIMEOUT_MS),
        host,
    ]
    completed = subprocess.run(
        command,
        capture_output=True,
        text=True,
        check=False,
    )
    output = completed.stdout + completed.stderr

    if completed.returncode != 0:
        return STATUS_DOWN, None

    match = re.search(r"time[=<]([0-9]+)ms", output)
    if match:
        return STATUS_UP, int(match.group(1))

    return STATUS_UNKNOWN, None


def record_latency(connection, result: PingResult) -> None:
    cursor = connection.cursor()
    cursor.execute(
        (
            "INSERT INTO monitoring_latency_log"
            " (device_id, latency_ms, status, checked_at)"
            " VALUES (%s, %s, %s, %s)"
        ),
        (
            result.device.device_id,
            result.latency_ms,
            result.status,
            result.checked_at,
        ),
    )
    connection.commit()
    cursor.close()


def monitor_once() -> None:
    print("monitor_once() called")  # Debug
    try:
        print("Opening DB connection...")
        with mysql_connection() as connection:
            print("DB connection opened.")
            try:
                devices = list(fetch_devices(connection))
                print(f"Fetched {len(devices)} devices")  # Add this line
            except Exception as fetch_err:
                print(f"Error fetching devices: {fetch_err}", file=sys.stderr)
                return

            if not devices:
                print("No active devices found in monitoring_devices table.")
                return

            for device in devices:
                print(f"Pinging device: {device.label} ({device.host})")  # Debug
                status, latency = ping_device(device.host)
                result = PingResult(
                    device=device,
                    status=status,
                    latency_ms=latency,
                    checked_at=datetime.now(timezone.utc),
                )
                try:
                    record_latency(connection, result)
                except Exception as log_err:
                    print(f"Error logging latency: {log_err}", file=sys.stderr)
                latency_display = f"{latency} ms" if latency is not None else "n/a"
                print(
                    f"[{result.checked_at.isoformat()}] {device.label}"
                    f" ({device.host}) -> {status} ({latency_display})"
                )
    except mysql.connector.Error as error:
        print(f"MySQL error: {error}", file=sys.stderr)
    except Exception as error:  # pylint: disable=broad-except
        print(f"Unexpected error: {error}", file=sys.stderr)


def run_forever() -> None:
    stop_requested = False

    def _signal_handler(signum, frame):  # noqa: D401, ANN001, ANN202
        nonlocal stop_requested
        stop_requested = True
        print(f"Received signal {signum}; shutting down...")

    signal.signal(signal.SIGINT, _signal_handler)
    signal.signal(signal.SIGTERM, _signal_handler)

    while not stop_requested:
        monitor_once()
        if stop_requested:
            break
        time.sleep(POLL_INTERVAL_SECONDS)


if __name__ == "__main__":
    print("Script started")  # Debug

    if not DB_CONFIG.get("user") or DB_CONFIG.get("password") is None:
        print(
            "Database credentials are not set."
            " Provide CONTROLS_DB_USER and CONTROLS_DB_PASSWORD env vars.",
            file=sys.stderr,
        )
        sys.exit(1)

    if os.environ.get("LATENCY_RUN_ONCE") == "1":
        monitor_once()
    else:
        run_forever()