From b8de48ebbca460a7bf4e699f2761df9b592d1498 Mon Sep 17 00:00:00 2001
From: Julien Eluard <julien.eluard@gmail.com>
Date: Sat, 3 Feb 2024 11:42:20 +0100
Subject: [PATCH] fix: cleanup

---
 packages/types/src/utils/ExecutionAddress.ts | 48 ++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 packages/types/src/utils/ExecutionAddress.ts

diff --git a/packages/types/src/utils/ExecutionAddress.ts b/packages/types/src/utils/ExecutionAddress.ts
new file mode 100644
index 000000000000..bfda06dc3579
--- /dev/null
+++ b/packages/types/src/utils/ExecutionAddress.ts
@@ -0,0 +1,48 @@
+import {keccak256} from "ethereum-cryptography/keccak.js";
+import {ByteVectorType} from "@chainsafe/ssz";
+
+export type ByteVector = Uint8Array;
+
+export class ExecutionAddressType extends ByteVectorType {
+  constructor() {
+    super(20, {typeName: "ExecutionAddress"});
+  }
+  toJson(value: ByteVector): unknown {
+    const str = super.toJson(value) as string;
+    return toChecksumAddress(str);
+  }
+}
+
+function isAddressValid(address: string): boolean {
+  return /^(0x)?[0-9a-f]{40}$/i.test(address);
+}
+
+/**
+ * Formats an address according to [ERC55](https://eips.ethereum.org/EIPS/eip-55)
+ */
+export function toChecksumAddress(address: string): string {
+  if (!isAddressValid(address)) {
+    throw Error(`Invalid address: ${address}`);
+  }
+
+  const rawAddress = address.toLowerCase().startsWith("0x") ? address.slice(2) : address;
+  const chars = rawAddress.split("");
+
+  // Inspired by https://github.com/ethers-io/ethers.js/blob/cac1da1f912c2ae9ba20f25aa51a91766673cd76/src.ts/address/address.ts#L8
+  const expanded = new Uint8Array(chars.length);
+  for (let i = 0; i < expanded.length; i++) {
+    expanded[i] = rawAddress[i].charCodeAt(0);
+  }
+
+  const hashed = keccak256(expanded);
+  for (let i = 0; i < chars.length; i += 2) {
+    if (hashed[i >> 1] >> 4 >= 8) {
+      chars[i] = chars[i].toUpperCase();
+    }
+    if ((hashed[i >> 1] & 0x0f) >= 8) {
+      chars[i + 1] = chars[i + 1].toUpperCase();
+    }
+  }
+
+  return "0x" + chars.join("");
+}