import { Contract } from "@ethersproject/contracts";
import { Provider } from "@ethersproject/abstract-provider";
import { namehash } from "@ethersproject/hash";

const REGISTRAR_ABI = [
  {
    constant: true,
    inputs: [
      {
        name: "node",
        type: "bytes32",
      },
    ],
    name: "resolver",
    outputs: [
      {
        name: "resolverAddress",
        type: "address",
      },
    ],
    payable: false,
    stateMutability: "view",
    type: "function",
  },
];
const REGISTRAR_ADDRESS = "0x00000000000C2E074eC69A0dFb2997BA6C7d2e1e";

const RESOLVER_ABI = [
  {
    constant: true,
    inputs: [
      {
        internalType: "bytes32",
        name: "node",
        type: "bytes32",
      },
    ],
    name: "contenthash",
    outputs: [
      {
        internalType: "bytes",
        name: "",
        type: "bytes",
      },
    ],
    payable: false,
    stateMutability: "view",
    type: "function",
  },
];

// cache the resolver contracts since most of them are the public resolver
function resolverContract(
  resolverAddress: string,
  provider: Provider
): Contract {
  return new Contract(resolverAddress, RESOLVER_ABI, provider);
}

/**
 * Fetches and decodes the result of an ENS contenthash lookup on mainnet to a URI
 * @param ensName to resolve
 * @param provider provider to use to fetch the data
 */
export default async function resolveENSContentHash(
  ensName: string,
  provider: Provider
): Promise<string> {
  const ensRegistrarContract = new Contract(
    REGISTRAR_ADDRESS,
    REGISTRAR_ABI,
    provider
  );
  const hash = namehash(ensName);
  const resolverAddress = await ensRegistrarContract.resolver(hash);
  return resolverContract(resolverAddress, provider).contenthash(hash);
}