lnbits-legend/lnbits/core/services.py

import trio  # type: ignore
import json
import httpx
from binascii import unhexlify
from typing import Optional, Tuple, Dict
from urllib.parse import urlparse, parse_qs
from quart import g
from ecdsa.util import sigencode_der  # type: ignore
from lnurl import LnurlErrorResponse, LnurlWithdrawResponse  # type: ignore

try:
    from typing import TypedDict  # type: ignore
except ImportError:  # pragma: nocover
    from typing_extensions import TypedDict

from lnbits import bolt11
from lnbits.helpers import urlsafe_short_hash
from lnbits.settings import WALLET
from lnbits.wallets.base import PaymentStatus, PaymentResponse

from .crud import get_wallet, create_payment, delete_payment, check_internal, update_payment_status, get_wallet_payment


def create_invoice(
    *,
    wallet_id: str,
    amount: int,  # in satoshis
    memo: str,
    description_hash: Optional[bytes] = None,
    extra: Optional[Dict] = None,
) -> Tuple[str, str]:
    invoice_memo = None if description_hash else memo
    storeable_memo = memo

    ok, checking_id, payment_request, error_message = WALLET.create_invoice(
        amount=amount, memo=invoice_memo, description_hash=description_hash
    )
    if not ok:
        raise Exception(error_message or "Unexpected backend error.")

    invoice = bolt11.decode(payment_request)

    amount_msat = amount * 1000
    create_payment(
        wallet_id=wallet_id,
        checking_id=checking_id,
        payment_request=payment_request,
        payment_hash=invoice.payment_hash,
        amount=amount_msat,
        memo=storeable_memo,
        extra=extra,
    )

    g.db.commit()
    return invoice.payment_hash, payment_request


def pay_invoice(
    *,
    wallet_id: str,
    payment_request: str,
    max_sat: Optional[int] = None,
    extra: Optional[Dict] = None,
    description: str = "",
) -> str:
    temp_id = f"temp_{urlsafe_short_hash()}"
    internal_id = f"internal_{urlsafe_short_hash()}"

    invoice = bolt11.decode(payment_request)
    if invoice.amount_msat == 0:
        raise ValueError("Amountless invoices not supported.")
    if max_sat and invoice.amount_msat > max_sat * 1000:
        raise ValueError("Amount in invoice is too high.")

    # put all parameters that don't change here
    PaymentKwargs = TypedDict(
        "PaymentKwargs",
        {
            "wallet_id": str,
            "payment_request": str,
            "payment_hash": str,
            "amount": int,
            "memo": str,
            "extra": Optional[Dict],
        },
    )
    payment_kwargs: PaymentKwargs = dict(
        wallet_id=wallet_id,
        payment_request=payment_request,
        payment_hash=invoice.payment_hash,
        amount=-invoice.amount_msat,
        memo=description or invoice.description or "",
        extra=extra,
    )

    # check_internal() returns the checking_id of the invoice we're waiting for
    internal_checking_id = check_internal(invoice.payment_hash)
    if internal_checking_id:
        # create a new payment from this wallet
        create_payment(checking_id=internal_id, fee=0, pending=False, **payment_kwargs)
    else:
        # create a temporary payment here so we can check if
        # the balance is enough in the next step
        fee_reserve = max(1000, int(invoice.amount_msat * 0.01))
        create_payment(checking_id=temp_id, fee=-fee_reserve, **payment_kwargs)

    # do the balance check
    wallet = get_wallet(wallet_id)
    assert wallet
    if wallet.balance_msat < 0:
        g.db.rollback()
        raise PermissionError("Insufficient balance.")
    else:
        g.db.commit()

    if internal_checking_id:
        # mark the invoice from the other side as not pending anymore
        # so the other side only has access to his new money when we are sure
        # the payer has enough to deduct from
        update_payment_status(checking_id=internal_checking_id, pending=False)

        # notify receiver asynchronously
        from lnbits.tasks import internal_invoice_paid

        try:
            internal_invoice_paid.send_nowait(internal_checking_id)
        except trio.WouldBlock:
            pass
    else:
        # actually pay the external invoice
        payment: PaymentResponse = WALLET.pay_invoice(payment_request)
        if payment.ok and payment.checking_id:
            create_payment(
                checking_id=payment.checking_id,
                fee=payment.fee_msat,
                preimage=payment.preimage,
                **payment_kwargs,
            )
            delete_payment(temp_id)
        else:
            raise Exception(payment.error_message or "Failed to pay_invoice on backend.")

    g.db.commit()
    return invoice.payment_hash


async def redeem_lnurl_withdraw(wallet_id: str, res: LnurlWithdrawResponse, memo: Optional[str] = None) -> None:
    _, payment_request = create_invoice(
        wallet_id=wallet_id,
        amount=res.max_sats,
        memo=memo or res.default_description or "",
        extra={"tag": "lnurlwallet"},
    )

    async with httpx.AsyncClient() as client:
        await client.get(
            res.callback.base,
            params={**res.callback.query_params, **{"k1": res.k1, "pr": payment_request}},
        )


async def perform_lnurlauth(callback: str) -> Optional[LnurlErrorResponse]:
    k1 = unhexlify(parse_qs(urlparse(callback).query)["k1"][0])
    key = g.wallet.lnurlauth_key
    sig = key.sign_digest_deterministic(k1, sigencode=sigencode_der)

    async with httpx.AsyncClient() as client:
        r = await client.get(
            callback,
            params={
                "k1": k1.hex(),
                "key": key.verifying_key.to_string("compressed").hex(),
                "sig": sig.hex(),
            },
        )
        try:
            resp = json.loads(r.text)
            if resp["status"] == "OK":
                return None

            return LnurlErrorResponse(reason=resp["reason"])
        except (KeyError, json.decoder.JSONDecodeError):
            return LnurlErrorResponse(
                reason=r.text[:200] + "..." if len(r.text) > 200 else r.text,
            )


def check_invoice_status(wallet_id: str, payment_hash: str) -> PaymentStatus:
    payment = get_wallet_payment(wallet_id, payment_hash)
    if not payment:
        return PaymentStatus(None)

    return WALLET.get_invoice_status(payment.checking_id)