from __future__ import annotations

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

from loguru import logger

from app.db import (
    add_watch_processed,
    health_snapshot_deliverable,
    load_watch_processed,
    save_health_snapshot,
)
from app.services import action as action_svc
from app.settings import Settings
from app.state import app_state
from app.watch_idle import IdleWatchWarnState, idle_warn_interval_sec, maybe_warn_idle_watch

_ACTION_IDLE_WARN_INTERVAL_SEC = idle_warn_interval_sec(
    "FISH_ACTION_WATCH_IDLE_WARN_INTERVAL_SEC"
)


def _state_path(settings: Settings) -> Path:
    if settings.action_watch_state_file is not None:
        return settings.action_watch_state_file
    assert settings.action_watch_dir is not None
    return settings.action_watch_dir / ".fishaction_watch_processed.json"


def iter_mp4(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() == ".mp4"
        )
    return sorted(
        p
        for p in watch_dir.iterdir()
        if p.is_file() and p.suffix.lower() == ".mp4"
    )


async def _run_inference_and_state(
    mp4: Path,
    settings: Settings,
    processed: Set[str],
    state_file: Path,
) -> None:
    key = str(mp4.resolve())
    if key in processed:
        return
    logger.info("[action-watch] inference: {}", mp4)
    async with app_state.action_lock:
        app_state.action_status = "running"
        try:
            # 返回 (第一个快照, 所有切片快照列表)
            first_snap, all_snaps = await asyncio.to_thread(
                action_svc.run_full_action, mp4, settings
            )

            # 将所有切片作为独立视频保存到数据库
            saved_count = 0
            for i, snap in enumerate(all_snaps):
                if health_snapshot_deliverable(snap):
                    # 为每个切片生成独立的 source_path
                    slice_key = f"{key}#slice{i}"
                    save_health_snapshot(settings, snap, source_path=slice_key)
                    saved_count += 1

            if saved_count == 0:
                logger.warning(
                    "[action-watch] no deliverable health snapshot for {}, skip SQLite",
                    mp4.name,
                )

            app_state.action_status = "idle"
            processed.add(key)
            if settings.action_watch_use_state_file:
                add_watch_processed(settings, key, "action")

            pred = (first_snap.raw_class_en or "").strip()
            logger.info(
                "[action-watch] done: {} -> {} (saved {} slices)",
                mp4.name,
                pred,
                saved_count,
            )
        except Exception as e:
            logger.exception("[action-watch] error on {}: {}", mp4, e)
            app_state.action_status = "idle"
            processed.add(key)
            if settings.action_watch_use_state_file:
                add_watch_processed(settings, key, "action")


async def watch_tick(
    settings: Settings,
    processed: Set[str],
    stability: Dict[str, tuple[int, int]],
    state_file: Path,
) -> bool:
    """处理一轮目录扫描；若处理了至少一个文件返回 True。"""
    assert settings.action_watch_dir is not None
    watch_dir = settings.action_watch_dir
    did = False
    seen_keys: Set[str] = set()
    for mp4 in iter_mp4(watch_dir, settings.action_watch_recursive):
        key = str(mp4.resolve())
        seen_keys.add(key)
        if key in processed:
            continue
        try:
            st = mp4.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.action_watch_stable_polls:
            await _run_inference_and_state(mp4, settings, processed, state_file)
            stability.pop(key, None)
            did = True
    for k in list(stability.keys()):
        if k not in seen_keys:
            del stability[k]
    return did


async def run_action_watch_loop(settings: Settings) -> None:
    assert settings.action_watch_dir is not None
    wd = settings.action_watch_dir
    if not wd.is_dir():
        logger.warning("[action-watch] skip: not a directory: {}", wd)
        return

    state_file = _state_path(settings)
    processed: Set[str] = (
        load_watch_processed(settings, state_file, "action")
        if settings.action_watch_use_state_file
        else set()
    )
    stability: Dict[str, tuple[int, int]] = {}

    logger.info(
        "[action-watch] watching {} (poll={}s, stable_polls={}, state={} {})",
        wd,
        settings.action_watch_poll_interval,
        settings.action_watch_stable_polls,
        "on" if settings.action_watch_use_state_file else "off",
        state_file if settings.action_watch_use_state_file else "",
    )

    idle_warn_state = IdleWatchWarnState()
    while True:
        did = await watch_tick(settings, processed, stability, state_file)
        maybe_warn_idle_watch(
            did_work=did,
            log_tag="action-watch",
            algo_name="FishAction",
            idle_hint="目录内无 .mp4、已全部处理完毕，或文件尚未达到稳定轮询次数",
            watch_dir=wd,
            state=idle_warn_state,
            interval_sec=_ACTION_IDLE_WARN_INTERVAL_SEC,
        )
        await asyncio.sleep(max(settings.action_watch_poll_interval, 0.1))