import json
from typing import Literal

import asyncpg

BG_EVENTS_CHANNEL = "bg_events"
MESSAGE_IDS_PER_EVENT = 500

EventKind = Literal["message", "edit", "delete", "reaction", "presence", "receipt"]


async def notify_bg_event(  # noqa: PLR0913
    pool: asyncpg.Pool,
    kind: EventKind,
    account_id: int,
    *,
    chat_id: int | None = None,
    message_id: int | None = None,
    message_ids: list[int] | None = None,
) -> None:
    payload: dict[str, object] = {"kind": kind, "account_id": account_id}
    if chat_id is not None:
        payload["chat_id"] = chat_id
    if message_id is not None:
        payload["message_id"] = message_id
    if message_ids is None:
        await _notify(pool, payload)
        return
    for start in range(0, len(message_ids), MESSAGE_IDS_PER_EVENT):
        chunk = message_ids[start : start + MESSAGE_IDS_PER_EVENT]
        await _notify(pool, {**payload, "message_ids": chunk})


async def _notify(pool: asyncpg.Pool, payload: dict[str, object]) -> None:
    await pool.execute(
        "SELECT pg_notify($1, $2)", BG_EVENTS_CHANNEL, json.dumps(payload)
    )