import { toFunctionSelector, type AbiFunction, type Hex } from "viem";

/** Find an AbiFunction by name, optionally disambiguating overloads with a predicate. */
export function abiFn(
  abi: readonly unknown[],
  name: string,
  pick?: (fn: AbiFunction) => boolean,
): AbiFunction {
  const fns = (abi as AbiFunction[]).filter((i) => i.type === "function" && i.name === name);
  if (fns.length === 0) throw new Error(`ABI has no function "${name}"`);
  const fn = pick ? fns.find(pick) : fns[0];
  if (!fn) throw new Error(`No overload of "${name}" matched the predicate`);
  return fn;
}

/** 4-byte selector for a function in an ABI (handles overloads via predicate). */
export function selector(
  abi: readonly unknown[],
  name: string,
  pick?: (fn: AbiFunction) => boolean,
): Hex {
  return toFunctionSelector(abiFn(abi, name, pick));
}