#!/usr/bin/env python3
"""Выгрузка публичной группы/канала, в которой мы не состоим.

`export.py run` ходит по iter_dialogs и потому видит только свои чаты.
Здесь сущность резолвится по @username и история читается напрямую.

    uv run fetch_public.py @cyschools --since 2026-03-04
"""
from __future__ import annotations

import argparse
import asyncio
import datetime as dt
import json
from pathlib import Path

from telethon import TelegramClient

import export as ex

ex.load_dotenv(ex.ROOT / ".env")


async def main_async(args) -> None:
    api_id, api_hash = ex.require_credentials()
    client = TelegramClient(args.session, api_id, api_hash)
    client.flood_sleep_threshold = 24 * 60 * 60
    await client.start()
    try:
        entity = await client.get_entity(args.chat)
        dialog_id = int(f"-100{entity.id}")
        folder = Path(args.out) / "chats" / f"{dialog_id}_{ex.slugify(getattr(entity, 'title', args.chat))}"
        folder.mkdir(parents=True, exist_ok=True)

        since = dt.datetime.fromisoformat(args.since).replace(tzinfo=dt.timezone.utc)
        (folder / "meta.json").write_text(json.dumps({
            "id": dialog_id,
            "name": getattr(entity, "title", None),
            "kind": ex.dialog_kind(entity),
            "username": getattr(entity, "username", None),
            "fetched_since": args.since,
        }, ensure_ascii=False, indent=2), encoding="utf-8")

        cache: dict = {}
        n = 0
        with (folder / "messages.jsonl").open("w", encoding="utf-8") as jsonl, \
             (folder / "messages_pretty.jsonl").open("w", encoding="utf-8") as pretty:
            async for msg in client.iter_messages(entity, offset_date=since, reverse=True):
                record = msg.to_dict()
                sender = await ex.sender_label(client, msg, cache)
                jsonl.write(json.dumps(record, ensure_ascii=False, cls=ex.Encoder) + "\n")
                pretty.write(json.dumps(ex.simplify_message(msg, sender, record),
                                        ensure_ascii=False, cls=ex.Encoder) + "\n")
                n += 1
                if n % 1000 == 0:
                    print(f"    … {n} ({msg.date:%Y-%m-%d})", flush=True)
        print(f"{folder.name}: {n} сообщений")
    finally:
        await client.disconnect()


def main() -> None:
    p = argparse.ArgumentParser()
    p.add_argument("chat")
    p.add_argument("--since", required=True)
    p.add_argument("--out", default=str(ex.ROOT / "out"))
    p.add_argument("--session", default=str(ex.ROOT / "tg_export.session"))
    asyncio.run(main_async(p.parse_args()))


if __name__ == "__main__":
    main()