import asyncio
import hashlib
import random
from datetime import datetime
from os import urandom
from typing import AsyncGenerator, Optional

from bolt11 import (
    Bolt11,
    Bolt11Exception,
    MilliSatoshi,
    TagChar,
    Tags,
    decode,
    encode,
)
from loguru import logger

from lnbits.settings import settings

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


class FakeWallet(Wallet):
    queue: asyncio.Queue = asyncio.Queue(0)
    secret: str = settings.fake_wallet_secret
    privkey: str = hashlib.pbkdf2_hmac(
        "sha256",
        secret.encode(),
        ("FakeWallet").encode(),
        2048,
        32,
    ).hex()

    async def status(self) -> StatusResponse:
        logger.info(
            "FakeWallet funding source is for using LNbits as a centralised,"
            " stand-alone payment system with brrrrrr."
        )
        return StatusResponse(None, 1000000000)

    async def create_invoice(
        self,
        amount: int,
        memo: Optional[str] = None,
        description_hash: Optional[bytes] = None,
        unhashed_description: Optional[bytes] = None,
        expiry: Optional[int] = None,
        payment_secret: Optional[bytes] = None,
        **_,
    ) -> InvoiceResponse:
        tags = Tags()

        if description_hash:
            tags.add(TagChar.description_hash, description_hash.hex())
        elif unhashed_description:
            tags.add(
                TagChar.description_hash,
                hashlib.sha256(unhashed_description).hexdigest(),
            )
        else:
            tags.add(TagChar.description, memo or "")

        if expiry:
            tags.add(TagChar.expire_time, expiry)

        # random hash
        checking_id = (
            self.privkey[:6]
            + hashlib.sha256(str(random.getrandbits(256)).encode()).hexdigest()[6:]
        )

        tags.add(TagChar.payment_hash, checking_id)

        if payment_secret:
            secret = payment_secret.hex()
        else:
            secret = urandom(32).hex()
        tags.add(TagChar.payment_secret, secret)

        bolt11 = Bolt11(
            currency="bc",
            amount_msat=MilliSatoshi(amount * 1000),
            date=int(datetime.now().timestamp()),
            tags=tags,
        )

        payment_request = encode(bolt11, self.privkey)

        return InvoiceResponse(True, checking_id, payment_request)

    async def pay_invoice(self, bolt11: str, _: int) -> PaymentResponse:
        try:
            invoice = decode(bolt11)
        except Bolt11Exception as exc:
            return PaymentResponse(ok=False, error_message=str(exc))

        if invoice.payment_hash[:6] == self.privkey[:6]:
            await self.queue.put(invoice)
            return PaymentResponse(True, invoice.payment_hash, 0)
        else:
            return PaymentResponse(
                ok=False, error_message="Only internal invoices can be used!"
            )

    async def get_invoice_status(self, _: str) -> PaymentStatus:
        return PaymentStatus(None)

    async def get_payment_status(self, _: str) -> PaymentStatus:
        return PaymentStatus(None)

    async def paid_invoices_stream(self) -> AsyncGenerator[str, None]:
        while True:
            value: Bolt11 = await self.queue.get()
            yield value.payment_hash