"""后台轮询目录中的 .svo2，跑 FishMeasure，写入 app_state.last_measure（与 ingest 共用状态）。"""

from __future__ import annotations

import asyncio
import traceback
from pathlib import Path
from typing import Dict, Set

from app.services import measure as measure_svc
from app.services.action_watch import load_processed, save_processed
from app.settings import Settings
from app.state import MeasureSnapshot, app_state


def _state_path(settings: Settings) -> Path:
    if settings.measure_watch_state_file is not None:
        return settings.measure_watch_state_file
    assert settings.measure_watch_dir is not None
    return settings.measure_watch_dir / ".fishmeasure_watch_processed.json"


def iter_svo2(watch_dir: Path, recursive: bool) -> list[Path]:
    if recursive:
        return sorted(
            p
            for p in watch_dir.rglob("*")
            if p.is_file() and p.suffix.lower() == ".svo2"
        )
    return sorted(
        p
        for p in watch_dir.iterdir()
        if p.is_file() and p.suffix.lower() == ".svo2"
    )


async def _run_measure_and_state(
    svo: Path,
    settings: Settings,
    processed: Set[str],
    state_file: Path,
) -> None:
    key = str(svo.resolve())
    if key in processed:
        return
    print(f"[measure-watch] inference: {svo}", flush=True)
    async with app_state.measure_lock:
        app_state.measure_status = "running"
        try:
            snap = await asyncio.to_thread(measure_svc.run_full_measure, svo, settings)
            app_state.last_measure = snap
            app_state.measure_status = "idle"
            processed.add(key)
            if settings.measure_watch_use_state_file:
                save_processed(state_file, processed)
            r0 = snap.result[0] if snap.result else {}
            w = r0.get("weight", "")
            print(f"[measure-watch] done: {svo.name} weight={w!r}", flush=True)
        except Exception as e:
            app_state.last_measure = MeasureSnapshot(
                result=[],
                video_left="",
                video_right="",
                error=str(e),
            )
            app_state.measure_status = "error"
            print(f"[measure-watch] error on {svo}: {e}", flush=True)
            traceback.print_exc()
            raise


async def watch_tick(
    settings: Settings,
    processed: Set[str],
    stability: Dict[str, tuple[int, int]],
    state_file: Path,
) -> bool:
    assert settings.measure_watch_dir is not None
    watch_dir = settings.measure_watch_dir
    did = False
    seen_keys: Set[str] = set()
    for svo in iter_svo2(watch_dir, settings.measure_watch_recursive):
        key = str(svo.resolve())
        seen_keys.add(key)
        if key in processed:
            continue
        try:
            st = svo.stat()
        except OSError:
            continue
        size = int(st.st_size)
        if size <= 0:
            stability.pop(key, None)
            continue
        last = stability.get(key)
        if last is None or last[0] != size:
            stability[key] = (size, 1)
        else:
            _, cnt = last
            stability[key] = (size, cnt + 1)
        _, cnt = stability[key]
        if cnt >= settings.measure_watch_stable_polls:
            try:
                await _run_measure_and_state(svo, settings, processed, state_file)
                stability.pop(key, None)
                did = True
            except Exception:
                stability[key] = (size, 1)
    for k in list(stability.keys()):
        if k not in seen_keys:
            del stability[k]
    return did


async def run_measure_watch_loop(settings: Settings) -> None:
    assert settings.measure_watch_dir is not None
    wd = settings.measure_watch_dir
    if not wd.is_dir():
        print(f"[measure-watch] skip: not a directory: {wd}", flush=True)
        return

    state_file = _state_path(settings)
    processed: Set[str] = (
        load_processed(state_file) if settings.measure_watch_use_state_file else set()
    )
    stability: Dict[str, tuple[int, int]] = {}

    print(
        f"[measure-watch] watching {wd} "
        f"(poll={settings.measure_watch_poll_interval}s, "
        f"stable_polls={settings.measure_watch_stable_polls}, "
        f"state={'on' if settings.measure_watch_use_state_file else 'off'} "
        f"{state_file if settings.measure_watch_use_state_file else ''})",
        flush=True,
    )

    while True:
        await watch_tick(settings, processed, stability, state_file)
        await asyncio.sleep(max(settings.measure_watch_poll_interval, 0.1))