import asyncio
import getpass
import os
import sys
from pathlib import Path

from telethon import TelegramClient
from telethon.sessions import StringSession


API_ID = int(os.getenv("TG_API_ID", "0"))
API_HASH = os.getenv("TG_API_HASH", "")
SESSION_FILE_PATH = os.getenv("SESSION_FILE_PATH", "./session_data/session.session")
TG_USE_IPV6 = os.getenv("TG_USE_IPV6", "true").lower() in {"1", "true", "yes"}
TG_CONNECT_TIMEOUT = int(os.getenv("TG_CONNECT_TIMEOUT", "30"))
TG_REQUEST_RETRIES = int(os.getenv("TG_REQUEST_RETRIES", "10"))
TG_CONNECTION_RETRIES = int(os.getenv("TG_CONNECTION_RETRIES", "20"))
TG_RETRY_DELAY = int(os.getenv("TG_RETRY_DELAY", "5"))


def validate() -> None:
    if API_ID <= 0:
        raise ValueError("Set TG_API_ID in environment")
    if not API_HASH:
        raise ValueError("Set TG_API_HASH in environment")


def choose_ip_mode(default_ipv6: bool) -> bool:
    default_label = "2" if default_ipv6 else "1"
    print("Choose connection mode for Telegram session generation:")
    print("1) IPv4")
    print("2) IPv6")

    if not sys.stdin.isatty():
        print(f"Non-interactive shell detected, using default from env: {'IPv6' if default_ipv6 else 'IPv4'}")
        return default_ipv6

    choice = input(f"Select [1/2] (default {default_label}): ").strip().lower()
    if choice in {"2", "ipv6", "v6"}:
        return True
    if choice in {"1", "ipv4", "v4"}:
        return False
    return default_ipv6


async def main() -> None:
    validate()
    selected_use_ipv6 = choose_ip_mode(TG_USE_IPV6)

    print("Starting Telegram login for StringSession generation")
    print(
        "Connection settings:",
        {
            "use_ipv6": selected_use_ipv6,
            "connect_timeout": TG_CONNECT_TIMEOUT,
            "request_retries": TG_REQUEST_RETRIES,
            "connection_retries": TG_CONNECTION_RETRIES,
            "retry_delay": TG_RETRY_DELAY,
        },
    )

    client = TelegramClient(
        StringSession(),
        API_ID,
        API_HASH,
        use_ipv6=selected_use_ipv6,
        timeout=TG_CONNECT_TIMEOUT,
        request_retries=TG_REQUEST_RETRIES,
        connection_retries=TG_CONNECTION_RETRIES,
        retry_delay=TG_RETRY_DELAY,
        auto_reconnect=True,
    )

    async with client:
        phone = input("Phone number (international format, e.g. +1234567890): ").strip()
        await client.send_code_request(phone)
        code = input("Telegram code: ").strip()

        try:
            await client.sign_in(phone=phone, code=code)
        except Exception:
            password = getpass.getpass("2FA password: ")
            await client.sign_in(password=password)

        session_string = client.session.save()
        session_path = Path(SESSION_FILE_PATH)
        session_path.parent.mkdir(parents=True, exist_ok=True)
        session_path.write_text(session_string + "\n", encoding="utf-8")
        print(f"Session saved to: {session_path.resolve()}")


if __name__ == "__main__":
    asyncio.run(main())