lndrest.py

#!/usr/bin/python3

import json
import os.path
import logging
import time
import requests
import math

import config

# import display
display_config = config.conf["atm"]["display"]
display = getattr(__import__("displays", fromlist=[display_config]), display_config)

logger = logging.getLogger("LNDREST")

verify = True
if(config.conf["lnd"]["verify"].lower() == "off"):
    verify = False
if(config.conf["lnd"]["verify"].lower() != "off"):
    verify = config.conf["lnd"]["verify"]

# TODO: Remove display calls from here to app.py

class InvoiceDecodeError(BaseException):
    pass


def payout(amt, payment_request):
    """Attempts to pay a BOLT11 invoice
    """
    data = {
        "payment_request": payment_request,
        "amt": math.floor(amt),
    }

    response = requests.post(
        str(config.conf["btcpay"]["url"]) + "/channels/transactions",
        headers={"Grpc-Metadata-macaroon": str(config.conf["lnd"]["macaroon"])},
        data=json.dumps(data),
        verify=verify,
    )
    res_json = response.json()

    if res_json.get("payment_error"):
        errormessage = res_json.get("payment_error")
        logger.error("Payment failed (%s)" % errormessage)
        print("Error: " + res_json.get("payment_error"))


def last_payment(payment_request):
    """Returns whether the last payment attempt succeeded or failed
    """
    url = str(config.conf["btcpay"]["url"]) + "/payments"

    data = {
        "include_incomplete": True,
    }

    response = requests.get(
        url,
        headers={"Grpc-Metadata-macaroon": str(config.conf["lnd"]["macaroon"])},
        data=json.dumps(data),
        verify=verify,
    )

    json_data = response.json()
    payment_data = json_data["payments"]
    _last_payment = payment_data[-1]

    if (_last_payment["payment_request"] == payment_request) and (
        _last_payment["status"] == "SUCCEEDED"
    ):
        logger.info("Payment succeeded")
        print("Payment succeeded")
        return True
    else:
        logger.info("Payment failed")
        print("Payment failed")
        return False


def decode_request(payment_request):
    """Decodes a BOLT11 invoice
    """
    if payment_request:
        url = str(config.conf["btcpay"]["url"]) + "/payreq/" + str(payment_request)
        response = requests.get(
            url,
            headers={"Grpc-Metadata-macaroon": config.conf["lnd"]["macaroon"]},
            verify=verify,
        )
        # successful response
        if response.status_code != 200:
            raise InvoiceDecodeError(
                "Invoice {} got bad decode response {}".format(
                    payment_request, response.text
                )
            )
        json_data = response.json()
        if "lnbc1" in payment_request:
            print("Zero sat invoice")
            return 0
        else:
            return int(json_data["num_satoshis"])
    else:
        pass


def handle_invoice():
    """Decode a BOLT11 invoice. Ensure that amount is correct or 0, then attempt to
    make the payment.
    """
    decode_req = decode_request(config.INVOICE)
    if decode_req in (math.floor(config.SATS), 0):
        payout(config.SATS, config.INVOICE)
        result = last_payment(config.INVOICE)

        if result:
            display.update_thankyou_screen()
        else:
            display.update_payment_failed()
            time.sleep(120)
    else:
        print("Please show correct invoice")


def evaluate_scan(qrcode):
    """Evaluates the scanned qr code for Lightning invoices.
    """
    if not qrcode:
        logger.error("QR code scanning failed")
        return False
    # check for a lightning invoice
    else:
        if "lnbc" in qrcode.lower():
            logger.info("Lightning invoice detected")
            invoice = qrcode.lower()
            # if invoice preceded with "lightning:" then chop it off so that we can
            # handle it correctly
            if "lightning:" in invoice:
                invoice = invoice[10:]
            return invoice
        else:
            logger.error("This QR does not contain a Lightning invoice")
            return False