Add boilerplate for managing return types, re-export Hex from @metamask/utils

Author: jeffsmale90

packages/delegation-core/src/returns.ts

@@ -0,0 +1,71 @@
+import { type BytesLike, bytesToHex, hexToBytes } from '@metamask/utils';
+
+import type { Hex } from './types';
+
+/**
+ * The possible return value types for encoding/decoding operations.
+ */
+export type ResultValue = 'hex' | 'bytes';
+
+/**
+ * Utility type for function return types based on ResultValue.
+ */
+export type ResultType<TResultValue extends ResultValue> =
+  TResultValue extends 'hex' ? Hex : Uint8Array;
+
+/**
+ * Base options interface for operations that can return hex or bytes.
+ */
+export type EncodingOptions<TResultValue extends ResultValue> = {
+  out: TResultValue;
+};
+
+/**
+ * Default options value with proper typing. Use this as your default parameter.
+ */
+export const defaultOptions = { out: 'hex' } as EncodingOptions<any>;
+
+/**
+ * Prepares a result by converting between hex and bytes based on options.
+ * @param result - The value to convert (either Uint8Array or Hex optionally prefixed with 0x).
+ * @param options - The options specifying the desired output format.
+ * @returns The converted value with proper type narrowing.
+ */
+export function prepareResult<TResultValue extends ResultValue>(
+  result: Uint8Array | Hex | string,
+  options: EncodingOptions<TResultValue>,
+): ResultType<TResultValue> {
+  if (options.out === 'hex') {
+    const hexValue = typeof result === 'string' ? result : bytesToHex(result);
+
+    return hexValue.startsWith('0x')
+      ? (hexValue as ResultType<TResultValue>)
+      : (`0x${hexValue}` as ResultType<TResultValue>);
+  }
+  const bytesValue = result instanceof Uint8Array ? result : hexToBytes(result);
+  return bytesValue as ResultType<TResultValue>;
+}
+
+/**
+ * Converts a bytes-like value to a hex string.
+ * @param bytesLike - The bytes-like value to convert.
+ * @returns The hex string representation of the bytes-like value.
+ */
+export const bytesLikeToHex = (bytesLike: BytesLike) => {
+  if (typeof bytesLike === 'string') {
+    return bytesLike;
+  }
+  return bytesToHex(bytesLike);
+};
+
+/**
+ * Converts a bytes-like value to a Uint8Array.
+ * @param bytesLike - The bytes-like value to convert.
+ * @returns The Uint8Array representation of the bytes-like value.
+ */
+export const bytesLikeToBytes = (bytesLike: BytesLike) => {
+  if (typeof bytesLike === 'string') {
+    return hexToBytes(bytesLike);
+  }
+  return bytesLike;
+};

packages/delegation-core/src/types.ts

@@ -0,0 +1 @@
+export type { Hex } from '@metamask/utils';