from __future__ import annotations

import logging
import os
import threading
import time
from dataclasses import dataclass
from typing import Any

from watchdog.events import FileSystemEvent, FileSystemEventHandler, FileSystemMovedEvent
from watchdog.observers.polling import PollingObserver

from scanner import resolve_runtime_path, scan_results


LOGGER = logging.getLogger("scheduler.watcher")


@dataclass(frozen=True)
class WatchConfig:
	dut_dir: str
	ref_dir: str
	smb_username: str
	smb_password: str
	smb_domain: str


class _ResultDirEventHandler(FileSystemEventHandler):
	def __init__(self, on_new_directory):
		super().__init__()
		self._on_new_directory = on_new_directory

	def on_created(self, event: FileSystemEvent) -> None:
		if event.is_directory:
			self._on_new_directory(event.src_path)

	def on_moved(self, event: FileSystemMovedEvent) -> None:
		if event.is_directory:
			self._on_new_directory(event.dest_path)


class ResultDirectoryWatcher:
	"""Watch DUT/REF result directories and trigger scans when new result folders appear."""

	def __init__(self, poll_interval_seconds: float = 2.0, min_scan_interval_seconds: float = 1.0):
		self._poll_interval_seconds = poll_interval_seconds
		self._min_scan_interval_seconds = min_scan_interval_seconds
		self._lock = threading.RLock()
		self._scan_lock = threading.Lock()
		self._observer: PollingObserver | None = None
		self._current_config: WatchConfig | None = None
		self._last_scan_monotonic = 0.0

	def configure_from_settings(self, settings: dict[str, Any]) -> None:
		dut_dir = _normalize_watch_path(settings.get("dutResultDir"))
		ref_dir = _normalize_watch_path(settings.get("refResultDir"))
		new_config = WatchConfig(
			dut_dir=dut_dir,
			ref_dir=ref_dir,
			smb_username=str(settings.get("smbUsername") or "").strip(),
			smb_password=str(settings.get("smbPassword") or ""),
			smb_domain=str(settings.get("smbDomain") or "").strip(),
		)

		with self._lock:
			if new_config == self._current_config and self._observer is not None:
				return

			self._stop_locked()
			self._current_config = new_config

			if not dut_dir or not ref_dir:
				LOGGER.info("result watcher disabled: DUT/REF result directories are not both set")
				return

			handler = _ResultDirEventHandler(self._on_new_directory)
			observer = PollingObserver(timeout=self._poll_interval_seconds)

			scheduled_count = 0
			for result_dir, label in ((dut_dir, "DUT"), (ref_dir, "REF")):
				if not os.path.isdir(result_dir):
					LOGGER.warning("%s result directory does not exist yet, skipping watch: %s", label, result_dir)
					continue
				observer.schedule(handler, result_dir, recursive=False)
				scheduled_count += 1

			if scheduled_count == 0:
				LOGGER.warning("result watcher not started: no valid result directories to watch")
				return

			observer.start()
			self._observer = observer
			LOGGER.info("result watcher started for DUT=%s REF=%s", dut_dir, ref_dir)

		self.scan_now(reason="startup")

	def _on_new_directory(self, directory_path: str) -> None:
		LOGGER.info("new result directory detected: %s", directory_path)
		self.scan_now(reason="directory-created")

	def scan_now(self, reason: str = "manual") -> None:
		with self._lock:
			config = self._current_config
			if config is None or not config.dut_dir or not config.ref_dir:
				return

			now = time.monotonic()
			if now - self._last_scan_monotonic < self._min_scan_interval_seconds:
				return
			self._last_scan_monotonic = now

		if not self._scan_lock.acquire(blocking=False):
			return

		def _run_scan() -> None:
			credentials = {
				"username": config.smb_username,
				"password": config.smb_password,
				"domain": config.smb_domain,
			}
			try:
				scan_results(config.dut_dir, config.ref_dir, smb_credentials=credentials)
				LOGGER.info("result scan finished (%s)", reason)
			except Exception:
				LOGGER.exception("result scan failed (%s)", reason)
			finally:
				self._scan_lock.release()

		threading.Thread(target=_run_scan, daemon=True).start()

	def stop(self) -> None:
		with self._lock:
			self._stop_locked()

	def _stop_locked(self) -> None:
		observer = self._observer
		self._observer = None
		if observer is not None:
			observer.stop()
			observer.join(timeout=5)
			LOGGER.info("result watcher stopped")


_WATCHER = ResultDirectoryWatcher()


def configure_result_watcher(settings: dict[str, Any]) -> None:
	_WATCHER.configure_from_settings(settings)


def stop_result_watcher() -> None:
	_WATCHER.stop()


def _normalize_watch_path(path_value: Any) -> str:
	if path_value is None:
		return ""
	cleaned = str(path_value).strip()
	if not cleaned:
		return ""
	return str(resolve_runtime_path(cleaned)).strip()