"""任务进度注册表（进程内内存，线程安全）。

供手动任务、定时任务在执行过程中上报进度，前端通过
GET /api/tasks/progress 轮询读取展示。

单 worker（uvicorn --workers 1）前提下，所有请求/任务线程共享同一份内存。
"""
import copy
import threading
from datetime import datetime, timezone
from typing import Optional

# 4 个稳定任务 key
TASK_KEYS = ("summarize", "tag_score_dedup", "generate_daily_brief", "bootstrap_taxonomy")

_progress: dict = {}
_lock = threading.Lock()


def _now_iso() -> str:
    return datetime.now(timezone.utc).isoformat()


def _init() -> None:
    """初始化所有任务 key 为 idle"""
    for key in TASK_KEYS:
        _progress[key] = {
            "status": "idle",
            "stage": "",
            "current": 0,
            "total": 0,
            "message": None,
            "started_at": None,
            "updated_at": None,
            "finished_at": None,
            "trigger": None,
        }


_init()


def update_progress(
    task_key: str,
    *,
    status: Optional[str] = None,
    stage: Optional[str] = None,
    current: Optional[int] = None,
    total: Optional[int] = None,
    message: Optional[str] = None,
    trigger: Optional[str] = None,
) -> None:
    """合并非 None 字段并盖时间戳"""
    with _lock:
        entry = _progress.get(task_key)
        if entry is None:
            entry = {
                "status": "idle", "stage": "", "current": 0, "total": 0,
                "message": None, "started_at": None, "updated_at": None,
                "finished_at": None, "trigger": None,
            }
            _progress[task_key] = entry

        now = _now_iso()
        if status == "running" and entry.get("started_at") is None:
            entry["started_at"] = now
        if status in ("success", "error"):
            entry["finished_at"] = now
        # 若重新进入 running，重置终态时间戳
        if status == "running":
            entry["finished_at"] = None

        if status is not None:
            entry["status"] = status
        if stage is not None:
            entry["stage"] = stage
        if current is not None:
            entry["current"] = current
        if total is not None:
            entry["total"] = total
        if message is not None:
            entry["message"] = message
        if trigger is not None:
            entry["trigger"] = trigger
        entry["updated_at"] = now


def report_loop_progress(
    task_key: str,
    index: int,
    total: int,
    stage: str,
    message: Optional[str] = None,
    every: int = 5,
) -> None:
    """紧凑循环进度上报：每 `every` 次或最后一次（index==total）才上报，减少加锁"""
    if index % every == 0 or index >= total:
        update_progress(task_key, status="running", stage=stage, current=index, total=total, message=message)


def get_progress(task_key: Optional[str] = None) -> dict:
    """返回深拷贝（单个或全部），防止序列化期间被并发修改"""
    with _lock:
        if task_key is not None:
            return copy.deepcopy(_progress.get(task_key))
        return copy.deepcopy(_progress)


def reset_progress(task_key: str) -> None:
    """重置单个任务为 idle（前端清除终态显示用）"""
    with _lock:
        if task_key in _progress:
            _progress[task_key] = {
                "status": "idle", "stage": "", "current": 0, "total": 0,
                "message": None, "started_at": None, "updated_at": None,
                "finished_at": None, "trigger": None,
            }