import json
import logging
from urllib.parse import parse_qsl

from fastapi import Depends, Header, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.config import settings
from app.core.database import get_db
from app.core.security import validate_init_data
from app.models.user import User

logger = logging.getLogger(__name__)


def _log_auth_failure(reason: str, init_data: str | None) -> None:
    parsed = dict(parse_qsl(init_data or "", keep_blank_values=True))
    logger.warning(
        "telegram auth failed: reason=%s init_len=%s has_hash=%s has_user=%s auth_date=%s bot_token_set=%s",
        reason,
        len(init_data or ""),
        bool(parsed.get("hash")),
        bool(parsed.get("user")),
        parsed.get("auth_date", ""),
        bool(settings.bot_token),
    )


async def get_current_user(
    x_telegram_init_data: str | None = Header(None, alias="X-Telegram-Init-Data"),
    db: AsyncSession = Depends(get_db),
) -> User:
    if not x_telegram_init_data:
        _log_auth_failure("missing_header", x_telegram_init_data)
        raise HTTPException(status_code=401, detail="Open this page from the Telegram bot Mini App")

    data = validate_init_data(x_telegram_init_data)
    if data is None:
        _log_auth_failure("invalid_init_data", x_telegram_init_data)
        raise HTTPException(status_code=401, detail="Invalid Telegram auth data")

    user_json = data.get("user", "{}")
    try:
        user_data = json.loads(user_json)
    except (json.JSONDecodeError, TypeError):
        _log_auth_failure("invalid_user_json", x_telegram_init_data)
        raise HTTPException(status_code=401, detail="Invalid user data")

    user_id = user_data.get("id")
    if not user_id:
        _log_auth_failure("missing_user_id", x_telegram_init_data)
        raise HTTPException(status_code=401, detail="Missing user id")

    result = await db.execute(select(User).where(User.id == user_id))
    user = result.scalar_one_or_none()

    if user is None:
        user = User(
            id=user_id,
            username=user_data.get("username"),
            first_name=user_data.get("first_name", ""),
            last_name=user_data.get("last_name"),
        )
        db.add(user)
        await db.commit()
        await db.refresh(user)
    else:
        user.username = user_data.get("username")
        user.first_name = user_data.get("first_name") or user.first_name
        user.last_name = user_data.get("last_name")
        await db.commit()

    return user