app/background.py

import asyncio
from datetime import datetime, timezone

from app.config import (
    ROOT_FOLDER_ID,
    POLL_SECONDS,
    HEARTBEAT_FILENAME,
    GOOGLE_TOKEN_JSON,
    SERVICE_NAME,
    VERSION,
)

from app.drive_client import build_drive_service, list_children, upsert_json_file


def _utc_now_iso() -> str:
    return datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")


def _make_hb_payload() -> dict:
    return {
        "service": SERVICE_NAME,
        "status": "alive",
        "last_seen": _utc_now_iso(),
        "version": VERSION,
        "root_folder_id": ROOT_FOLDER_ID,
    }


async def worker_loop():
    print("[STARTUP] Worker loop starting")

    if not GOOGLE_TOKEN_JSON or not GOOGLE_TOKEN_JSON.strip():
        print("[ERROR] Missing GOOGLE_TOKEN_JSON (HF Secret).")
        return

    if not ROOT_FOLDER_ID or not ROOT_FOLDER_ID.strip():
        print("[ERROR] Missing ROOT_FOLDER_ID (HF Variable).")
        return

    # Build Drive client once; we’ll rebuild on transient failures
    service = build_drive_service(GOOGLE_TOKEN_JSON)

    # ----------------------------
    # 1) RUN ONCE IMMEDIATELY
    # ----------------------------
    try:
        files = list_children(service, ROOT_FOLDER_ID, page_size=20)
        print(f"[DRIVE] Found {len(files)} files")
        if files:
            print("[DRIVE] Sample:", ", ".join([f["name"] for f in files[:5]]))

        upsert_json_file(service, ROOT_FOLDER_ID, HEARTBEAT_FILENAME, _make_hb_payload())
        print(f"[HEARTBEAT] Wrote {HEARTBEAT_FILENAME} to Drive root (folder={ROOT_FOLDER_ID})")

    except Exception as e:
        print(f"[ERROR] Startup drive/heartbeat failed: {e}")
        # backoff so we don't thrash on startup
        await asyncio.sleep(10)

    # ----------------------------
    # 2) POLL FOREVER
    # ----------------------------
    while True:
        try:
            files = list_children(service, ROOT_FOLDER_ID, page_size=20)
            print(f"[DRIVE] Found {len(files)} files")
            if files:
                print("[DRIVE] Sample:", ", ".join([f["name"] for f in files[:5]]))

            upsert_json_file(service, ROOT_FOLDER_ID, HEARTBEAT_FILENAME, _make_hb_payload())
            print(f"[HEARTBEAT] Updated {HEARTBEAT_FILENAME} (every {POLL_SECONDS}s)")

        except Exception as e:
            # Transient HF/network issues show up here (Broken pipe, EOF, etc.)
            print(f"[ERROR] Drive/heartbeat poll failed: {e}")

            # Retry strategy:
            # 1) Rebuild drive client (fresh TLS session)
            # 2) Retry heartbeat write once
            try:
                service = build_drive_service(GOOGLE_TOKEN_JSON)
                upsert_json_file(service, ROOT_FOLDER_ID, HEARTBEAT_FILENAME, _make_hb_payload())
                print("[HEARTBEAT] Recovered after rebuild/retry")

            except Exception as e2:
                print(f"[ERROR] Recovery retry failed: {e2}")

            # small backoff so we don't spam on repeated failures
            await asyncio.sleep(10)

        # normal poll interval
        await asyncio.sleep(POLL_SECONDS)