imports_ok = True
try:
    import grpc
    from google import protobuf
except ImportError:  # pragma: nocover
    imports_ok = False


import base64
import binascii
import hashlib
from os import environ, error, getenv
from typing import AsyncGenerator, Dict, Optional

from loguru import logger

from .macaroon import AESCipher, load_macaroon

if imports_ok:
    import lnbits.wallets.lnd_grpc_files.lightning_pb2 as ln
    import lnbits.wallets.lnd_grpc_files.lightning_pb2_grpc as lnrpc

from .base import (
    InvoiceResponse,
    PaymentResponse,
    PaymentStatus,
    StatusResponse,
    Wallet,
)


def get_ssl_context(cert_path: str):
    import ssl

    context = ssl.SSLContext(ssl.PROTOCOL_TLS)
    context.options |= ssl.OP_NO_SSLv2
    context.options |= ssl.OP_NO_SSLv3
    context.options |= ssl.OP_NO_TLSv1
    context.options |= ssl.OP_NO_TLSv1_1
    context.options |= ssl.OP_NO_COMPRESSION
    context.set_ciphers(
        ":".join(
            [
                "ECDHE+AESGCM",
                "ECDHE+CHACHA20",
                "DHE+AESGCM",
                "DHE+CHACHA20",
                "ECDH+AESGCM",
                "DH+AESGCM",
                "ECDH+AES",
                "DH+AES",
                "RSA+AESGCM",
                "RSA+AES",
                "!aNULL",
                "!eNULL",
                "!MD5",
                "!DSS",
            ]
        )
    )
    context.load_verify_locations(capath=cert_path)
    return context


def parse_checking_id(checking_id: str) -> bytes:
    return base64.b64decode(checking_id.replace("_", "/"))


def stringify_checking_id(r_hash: bytes) -> str:
    return base64.b64encode(r_hash).decode("utf-8").replace("/", "_")


# Due to updated ECDSA generated tls.cert we need to let gprc know that
# we need to use that cipher suite otherwise there will be a handhsake
# error when we communicate with the lnd rpc server.
environ["GRPC_SSL_CIPHER_SUITES"] = "HIGH+ECDSA"


class LndWallet(Wallet):
    def __init__(self):
        if not imports_ok:  # pragma: nocover
            raise ImportError(
                "The `grpcio` and `protobuf` library must be installed to use `GRPC LndWallet`. Alternatively try using the LndRESTWallet."
            )

        endpoint = getenv("LND_GRPC_ENDPOINT")
        self.endpoint = endpoint[:-1] if endpoint.endswith("/") else endpoint
        self.port = int(getenv("LND_GRPC_PORT"))
        self.cert_path = getenv("LND_GRPC_CERT") or getenv("LND_CERT")

        macaroon = (
            getenv("LND_GRPC_MACAROON")
            or getenv("LND_GRPC_ADMIN_MACAROON")
            or getenv("LND_ADMIN_MACAROON")
            or getenv("LND_GRPC_INVOICE_MACAROON")
            or getenv("LND_INVOICE_MACAROON")
        )

        encrypted_macaroon = getenv("LND_GRPC_MACAROON_ENCRYPTED")
        if encrypted_macaroon:
            macaroon = AESCipher(description="macaroon decryption").decrypt(
                encrypted_macaroon
            )
        self.macaroon = load_macaroon(macaroon)

        cert = open(self.cert_path, "rb").read()
        creds = grpc.ssl_channel_credentials(cert)
        auth_creds = grpc.metadata_call_credentials(self.metadata_callback)
        composite_creds = grpc.composite_channel_credentials(creds, auth_creds)
        channel = grpc.aio.secure_channel(
            f"{self.endpoint}:{self.port}", composite_creds
        )
        self.rpc = lnrpc.LightningStub(channel)

    def metadata_callback(self, _, callback):
        callback([("macaroon", self.macaroon)], None)

    async def status(self) -> StatusResponse:
        try:
            resp = await self.rpc.ChannelBalance(ln.ChannelBalanceRequest())
        except Exception as exc:
            return StatusResponse(str(exc), 0)

        return StatusResponse(None, resp.balance * 1000)

    async def create_invoice(
        self,
        amount: int,
        memo: Optional[str] = None,
        description_hash: Optional[bytes] = None,
    ) -> InvoiceResponse:
        params: Dict = {"value": amount, "expiry": 600, "private": True}

        if description_hash:
            params["description_hash"] = base64.b64encode(
                hashlib.sha256(description_hash).digest()
            )  # as bytes directly
        else:
            params["memo"] = memo or ""

        try:
            req = ln.Invoice(**params)
            resp = await self.rpc.AddInvoice(req)
        except Exception as exc:
            error_message = str(exc)
            return InvoiceResponse(False, None, None, error_message)

        checking_id = stringify_checking_id(resp.r_hash)
        payment_request = str(resp.payment_request)
        return InvoiceResponse(True, checking_id, payment_request, None)

    async def pay_invoice(self, bolt11: str, fee_limit_msat: int) -> PaymentResponse:
        fee_limit_fixed = ln.FeeLimit(fixed=fee_limit_msat // 1000)
        req = ln.SendRequest(payment_request=bolt11, fee_limit=fee_limit_fixed)
        resp = await self.rpc.SendPaymentSync(req)

        if resp.payment_error:
            return PaymentResponse(False, "", 0, None, resp.payment_error)

        r_hash = hashlib.sha256(resp.payment_preimage).digest()
        checking_id = stringify_checking_id(r_hash)
        fee_msat = resp.payment_route.total_fees_msat
        preimage = resp.payment_preimage.hex()
        return PaymentResponse(True, checking_id, fee_msat, preimage, None)

    async def get_invoice_status(self, checking_id: str) -> PaymentStatus:
        try:
            r_hash = parse_checking_id(checking_id)
            if len(r_hash) != 32:
                raise binascii.Error
        except binascii.Error:
            # this may happen if we switch between backend wallets
            # that use different checking_id formats
            return PaymentStatus(None)

        resp = await self.rpc.LookupInvoice(ln.PaymentHash(r_hash=r_hash))
        if resp.settled:
            return PaymentStatus(True)

        return PaymentStatus(None)

    async def get_payment_status(self, checking_id: str) -> PaymentStatus:
        return PaymentStatus(True)

    async def paid_invoices_stream(self) -> AsyncGenerator[str, None]:
        request = ln.InvoiceSubscription()
        try:
            async for i in self.rpc.SubscribeInvoices(request):
                if not i.settled:
                    continue

                checking_id = stringify_checking_id(i.r_hash)
                yield checking_id
        except error:
            logger.error(error)

        logger.error(
            "lost connection to lnd InvoiceSubscription, please restart lnbits."
        )