getContract.ts

import {
  Abi,
  Account,
  Address,
  Chain,
  GetContractParameters,
  GetContractReturnType,
  Hex,
  PublicClient,
  Transport,
  WalletClient,
  WriteContractParameters,
  type ContractFunctionName,
  type ContractFunctionArgs,
  getContract as viem_getContract,
} from "viem";
import { UnionOmit } from "./type-utils/common";
import { writeContract } from "./writeContract";

// copied from viem because this isn't exported
// TODO: import from viem?
function getFunctionParameters(values: [args?: readonly unknown[], options?: object]): {
  args: readonly unknown[];
  options: object;
} {
  const hasArgs = values.length && Array.isArray(values[0]);
  const args = hasArgs ? values[0]! : [];
  const options = (hasArgs ? values[1] : values[0]) ?? {};
  return { args, options };
}

export type ContractWrite = {
  id: string;
  request: WriteContractParameters;
  result: Promise<Hex>;
};

export type GetContractOptions<
  TTransport extends Transport,
  TAddress extends Address,
  TAbi extends Abi,
  TChain extends Chain,
  TAccount extends Account,
  TPublicClient extends PublicClient<TTransport, TChain>,
  TWalletClient extends WalletClient<TTransport, TChain, TAccount>,
> = GetContractParameters<
  TTransport,
  TChain,
  TAccount,
  TAbi,
  { public: TPublicClient; wallet: TWalletClient },
  TAddress
> & {
  onWrite?: (write: ContractWrite) => void;
};

// TODO: migrate away from this approach once we can hook into viem: https://github.com/wagmi-dev/viem/discussions/1230

/** @deprecated Use `walletClient.extend(transactionQueue()).extend(writeObserver({ onWrite }))` and viem's `getContract` instead. */
export function getContract<
  TTransport extends Transport,
  TAddress extends Address,
  TAbi extends Abi,
  TChain extends Chain,
  TAccount extends Account,
  TPublicClient extends PublicClient<TTransport, TChain>,
  TWalletClient extends WalletClient<TTransport, TChain, TAccount>,
>({
  abi,
  address,
  client: { public: publicClient, wallet: walletClient },
  onWrite,
}: GetContractOptions<
  TTransport,
  TAddress,
  TAbi,
  TChain,
  TAccount,
  TPublicClient,
  TWalletClient
>): GetContractReturnType<TAbi, { public: TPublicClient; wallet: TWalletClient }, TAddress> {
  const contract = viem_getContract({
    abi,
    address,
    client: {
      public: publicClient,
      wallet: walletClient,
    },
  }) as unknown as GetContractReturnType<TAbi, { public: TPublicClient; wallet: TWalletClient }, TAddress> & {
    write: unknown;
  };

  if (contract.write) {
    // Replace write calls with our own. Implemented ~the same as viem, but adds better handling of nonces (via queue + retries).
    let nextWriteId = 0;
    contract.write = new Proxy(
      {},
      {
        get(_, functionName: string) {
          return (
            ...parameters: [
              args?: readonly unknown[],
              options?: UnionOmit<WriteContractParameters, "abi" | "address" | "functionName" | "args">,
            ]
          ) => {
            const { args, options } = getFunctionParameters(parameters);
            const request = {
              abi,
              address,
              functionName,
              args,
              ...options,
              onWrite,
            } as unknown as WriteContractParameters<
              TAbi,
              ContractFunctionName<TAbi, "nonpayable" | "payable">,
              ContractFunctionArgs<TAbi, "nonpayable" | "payable">,
              TChain,
              TAccount
            >;
            const result = writeContract(walletClient, request);

            const id = `${walletClient.chain.id}:${walletClient.account.address}:${nextWriteId++}`;
            onWrite?.({ id, request: request as WriteContractParameters, result });

            return result;
          };
        },
      },
    );
  }

  return contract as unknown as GetContractReturnType<TAbi, { public: TPublicClient; wallet: TWalletClient }, TAddress>;
}