Schedule Telegram channel posts from your bot

from datetime import datetime
from zoneinfo import ZoneInfo
from clickruntime import on_trigger, credentials, http, state

OWNER, CHANNEL, TZ = 123456789, "@yourchannel", ZoneInfo("Europe/London")

def tg(method, **params):
    r = http.post(f"https://api.telegram.org/bot{credentials.secret('TELEGRAM_BOT_TOKEN')}/{method}", json=params)
    r.raise_for_status()
    return r.json()["result"]

@on_trigger
def run(event):
    queue = state.get("queue") or []
    msg = (event.get("json") or {}).get("message")
    if msg:  # a command from the owner
        if msg["chat"]["id"] != OWNER:
            return {"skipped": True}
        text = msg.get("text", "")
        if text.startswith("/at "):
            parts = text.split(" ", 3)
            when = datetime.strptime(f"{parts[1]} {parts[2]}", "%Y-%m-%d %H:%M").replace(tzinfo=TZ)
            n = (state.get("n") or 0) + 1
            queue.append({"n": n, "at": when.timestamp(), "text": parts[3]})
            state.set("n", n)
            reply = f"Scheduled #{n} for {when:%a %d %b %H:%M}"
        elif text.startswith("/cancel "):
            queue = [q for q in queue if str(q["n"]) != text.split()[1]]
            reply = "Removed."
        else:
            reply = "\n".join(f"#{q['n']} {datetime.fromtimestamp(q['at'], TZ):%d %b %H:%M} {q['text'][:40]}" for q in queue) or "Nothing scheduled."
        state.set("queue", queue)
        tg("sendMessage", chat_id=OWNER, text=reply)
        return {"queued": len(queue)}
    now = datetime.now(TZ).timestamp()  # schedule: post what is due
    due = [q for q in queue if q["at"] <= now]
    for q in due:
        tg("sendMessage", chat_id=CHANNEL, text=q["text"])
        tg("sendMessage", chat_id=OWNER, text=f"Posted #{q['n']} to {CHANNEL}")
    state.set("queue", [q for q in queue if q["at"] > now])
    return {"posted": len(due)}