"""Debounced file watcher and cron scheduler for opted-in knowledge bindings."""

from __future__ import annotations

import asyncio
import logging
from datetime import UTC, datetime
from typing import Any

from croniter import croniter

from app.gateway.skill_knowledge_job_executor import _skill_directory
from deerflow.config.system_settings import load_system_settings
from deerflow.skill_knowledge import scan_skill

logger = logging.getLogger(__name__)


class SkillKnowledgeAutoSyncService:
    def __init__(self, app: Any, *, poll_seconds: float = 10.0) -> None:
        self.app = app
        self.store = app.state.skill_knowledge_store
        self.poll_seconds = poll_seconds
        self._task: asyncio.Task | None = None
        self._wake = asyncio.Event()
        self._observed: dict[str, tuple[str, datetime]] = {}
        self._schedule_expression = ""
        self._next_schedule: datetime | None = None

    def start(self) -> None:
        if self._task is None or self._task.done():
            self._task = asyncio.create_task(self._loop())

    def nudge(self) -> None:
        self._wake.set()

    async def close(self) -> None:
        if self._task is None:
            return
        self._task.cancel()
        try:
            await self._task
        except asyncio.CancelledError:
            pass

    async def _queue_skill(
        self,
        skill_name: str,
        bindings: list[dict[str, Any]],
        *,
        trigger: str,
        review_mode: str,
    ) -> None:
        targets = [
            {
                "target_type": binding["target_type"],
                "target_mode": binding["target_mode"],
                "target_id": binding["target_id"],
                "target_name": binding["target_name"],
                "remote_business_key": binding.get("remote_business_key"),
            }
            for binding in bindings
        ]
        job = await self.store.create_job(
            skill_names=[skill_name],
            targets=targets,
            created_by=None,
            trigger=trigger,
            review_mode=review_mode,
        )
        if job["total_count"]:
            self.app.state.skill_knowledge_dispatcher.nudge()

    async def _watch(
        self,
        bindings_by_skill: dict[str, list[dict[str, Any]]],
        *,
        debounce_seconds: int,
        write_remote_enabled: bool,
        review_mode: str,
    ) -> None:
        now = datetime.now(UTC)
        for skill_name, bindings in bindings_by_skill.items():
            try:
                root = _skill_directory(self.app.state.config, skill_name)
                scan = await asyncio.to_thread(scan_skill, skill_name, root)
            except Exception:
                logger.exception("Failed to fingerprint skill %s", skill_name)
                continue
            synced = {str(binding.get("synced_digest") or "") for binding in bindings}
            if synced == {scan.source_digest}:
                self._observed.pop(skill_name, None)
                continue
            await self.store.mark_skill_stale(skill_name)
            previous = self._observed.get(skill_name)
            if previous is None or previous[0] != scan.source_digest:
                self._observed[skill_name] = (scan.source_digest, now)
                continue
            if (now - previous[1]).total_seconds() < debounce_seconds:
                continue
            if write_remote_enabled:
                current = await self.store.list_bindings(skill_names=[skill_name])
                stale = [binding for binding in current if binding.get("auto_sync_enabled") and binding.get("status") == "stale"]
                if stale:
                    await self._queue_skill(
                        skill_name,
                        stale,
                        trigger="watcher",
                        review_mode=review_mode,
                    )
            self._observed.pop(skill_name, None)

    def _schedule_due(self, expression: str, now: datetime) -> bool:
        if expression != self._schedule_expression or self._next_schedule is None:
            self._schedule_expression = expression
            self._next_schedule = croniter(expression, now).get_next(datetime)
            return False
        if now < self._next_schedule:
            return False
        self._next_schedule = croniter(expression, now).get_next(datetime)
        return True

    async def _tick(self) -> None:
        settings = (await asyncio.to_thread(load_system_settings)).skill_knowledge_auto_sync
        bindings = [row for row in await self.store.list_bindings() if row.get("auto_sync_enabled")]
        by_skill: dict[str, list[dict[str, Any]]] = {}
        for binding in bindings:
            by_skill.setdefault(str(binding["skill_name"]), []).append(binding)
        if settings.watch_enabled:
            await self._watch(
                by_skill,
                debounce_seconds=settings.debounce_seconds,
                write_remote_enabled=settings.write_remote_enabled,
                review_mode=settings.review_mode,
            )
        if settings.schedule_enabled and settings.write_remote_enabled and by_skill and self._schedule_due(settings.schedule_cron, datetime.now(UTC)):
            for skill_name, skill_bindings in by_skill.items():
                await self._queue_skill(
                    skill_name,
                    skill_bindings,
                    trigger="scheduled",
                    review_mode=settings.review_mode,
                )

    async def _loop(self) -> None:
        while True:
            try:
                await self._tick()
            except Exception:
                logger.exception("Skill knowledge automatic sync tick failed")
            try:
                await asyncio.wait_for(self._wake.wait(), timeout=self.poll_seconds)
            except TimeoutError:
                pass
            self._wake.clear()