"""
progress_bus.py - 07 May 2025
"""
from __future__ import annotations
import asyncio, json, time
from typing import Dict, Any

# in-mem state
_progress: Dict[str, Dict[str, Any]] = {}
_watchers: Dict[str, list[asyncio.Queue[str]]] = {}
_TTL = 60 * 60        # keep finished/error records 1 h

def _now() -> float: return time.time()

def register(sid: str) -> None:
    _progress[sid] = dict(pct=0, progress="", status="running", ts=_now())
    _broadcast(sid)

def update(sid: str, *, pct: float | None = None,
           progress: str | None = None, status: str | None = None) -> None:
    if sid not in _progress:
        register(sid)
    p = _progress[sid]
    if pct is not None:      p["pct"] = pct
    if progress is not None: p["progress"] = progress
    if status is not None:   p["status"] = status
    p["ts"] = _now()
    _broadcast(sid)

def get(sid: str) -> Dict[str, Any]:
    _gc()
    return _progress.get(sid, {"status": "idle"})

def clear(sid: str) -> None:
    _progress.pop(sid, None)
    _watchers.pop(sid, None)

#  SSE integration
def subscribe(sid: str) -> asyncio.Queue[str]:
    q: asyncio.Queue[str] = asyncio.Queue(maxsize=16)
    _watchers.setdefault(sid, []).append(q)
    # immediately push current state
    q.put_nowait(json.dumps({"sid": sid, **get(sid)}))
    return q

def _broadcast(sid: str) -> None:
    if sid not in _watchers:
        return
    payload = json.dumps({"sid": sid, **_progress[sid]})
    for q in list(_watchers[sid]):
        try:
            q.put_nowait(payload)
        except asyncio.QueueFull:
            pass  # drop frame

# garbage collector
def _gc() -> None:
    now = _now()
    stale = [k for k, v in _progress.items()
             if v["status"] in ("finished", "error") and now - v["ts"] > _TTL]
    for k in stale:
        clear(k)